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NBS Technical Note 1247
Review of Nondestructive Evaluation Methods
Applicable to Construction Materials and Structures
Robert G. Mathey and James R. Clifton
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Tm he National Bureau of Standards' was established by an act of Congress on March 3, 1901. The Bureau's overall
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'Headquarters and Laboratories at Gaithersburg, MD, unless otherwise noted; mailing address
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^Located at Boulder, CO, with some elements at Gaithersburg,^D
JElesearch luformation Center
iNalioaal t>ureau of Standards
Gaithersburg, IVIaryknd 20899
QCfOo
NBS Technical Note 1247 ^f ^/
Review of Nondestructive Evaluation Methods
Applicable to Construction Materials and Structures
Robert G. Mathey and James R. Clifton
Center for Building TechnologyNational Engineering Laboratory
National Bureau of Standards
Gaithersburg, MD 20899
Prepared for:
Naval Civil Engineering Laboratory
Port Hueneme, CA 93043-5003
June 1988
U.S. Department of CommerceC. Waiiam Verity, Secretary
National Bureau of Standards
Ernest Ambler, Director
National Bureau of Standards U.S. Government Printing Office For sale by the Superintendent
Technical Note 1247 Washington: 1988 of Documents,
Natl. Bur. Stand. (U.S.), U.S. Government Printing Office,
Tech. Note 1247 Washington, DC 20402
203 pages (June 1988)
CODEN: NBTNAE
PREFACE
This is the second compilation of nondestructive evaluation (NDE) methods for
construction materials and structures prepared by the Center for BuildingTechnology. Significant advances in NDE methods for construction materials andstructures have been made since the first report was published in 1982 [1].
Readers, undoubtedly, are aware of NDE methods not included in the presentcompilation, which should be included in a future version. The authors welcomesuggestions regarding additions to the compilation of NDE methods.
An extensive effort was required in the preparation of this report and if the
anticipated growth in NDE occurs then preparation of a future version, in thesame format, may become unwieldy. It is recommended, therefore, that startingwith the present report the compilation be coded in an expert system form.
This would facilitate the identification of appropriate NDE methods for specificmaterials and problems. Also, additions to the compilation could be easilyintroduced into the expert system program, thereby, reflecting the currentstate-of-the-art
.
During the preparation of this report, it became obvious to the authors that animproved bases needs to be developed for interpreting the results of NDEinspections. At present, interpretation is frequently based on intuition andpast experiences which are generally not recorded and, thus, are not of help to
new inspectors. Without an adequate bases for interpretation, incorrectdecisions could be made regarding the condition of building materials, components,or structures. Therefore, it is recommended that a standard practice, guide,or methodology be developed for interpreting the results of NDE tests.
iii
ABSTRACT
Nondestructive evaluation (NDE) methods for evaluating in situ constructionmaterials and for condition assessment of building components and systems wereidentified and are described. This report is intended to help inspectors andthose involved in condition assessment choose appropriate NDE methods for
specific building materials, components, and systems. Important properties ofbuilding materials along with important performance requirements for buildingcomponents are listed, and appropriate NDE methods for determining theseproperties are recommended. In many cases the advantages and limitations of
the NDE methods are presented. Potential NDE methods which may or may notrequire further research and development before they are ready for routine usewere also identified and are briefly described. In addition, ASTM standardsfor NDE methods for concrete and other building materials and components wereidentified.
In a related aspect of the study, current Navy practices relative to the useof NDE methods in the construction and service cycle of buildings and otherstructures were reviewed. This review was based on Navy reports and documentsprovided by NCEL and NAVFAC, and on discussions with NAVFAC personnel involvedwith buildings and structures problems where NDE methods are used for diagnosticpurposes. Navy Guide Specifications were examined for required tests, bothNDE and destructive, of in situ building materials and components.
Key Words: Building components; building diagnostics; building materials;condition assessment; construction materials; in situ evaluation;
nondestructive evaluation.
iv
TABLE OF CONTENTS
Page
Abstract Iv
1 . INTRODUCTION 1
1 .
1
Background 1
1.2 Objective 2
1 .
3
Scope 2
2 . REV lEW OF CURRENT NDE NAVY PRACT ICES 4
2.1 Guide Specifications 4
2.2 Summary of NDE Practices Obtained from Brief Discussions withNAVFAC Personnel 4
2.3 Review of Needed and Presently Used Methods Based on theResults of Responses to NCEL Questionnaires 5
2.3.1 List of Reported Needed NDE Methods 6
2.3.2 List of Reported Presently Used NDE Methods 7
2 .4 Navy NDE Publications 8
3
.
NDE METHODS 11
4. NDE TABLES 13
4.1 Building Materials, Components, and Systems 13
4.2 Survey of NDE Methods 14
5. DESCRIPTION OF NDE METHODS 37
5.1 Acoustic Emission Method 37
5.2 Acoustic Impact Method 395.3 Air Flow 41
5.3.1 Pltot Traverse 41
5.4 Air Infiltration Measurements 42
5.4.1 Tracer-Gas Decay Method 425.4.2 Fan Pressurlzatlon Technique 435.4.3 Acoustic Method 445.4.4 Smoke Tracer 45
5.5 Air Permeability 465.6 Break-Off Method 465.7 Cast-ln-Place Pullout 47
TABLE OF CONTENTS (Continued)
Page
5.8 Electrical Potential Measurements 49
5.9 Electromagnetic Methods 51
5.9.1 Eddy Current Inspection 51
5.9.2 Magneto- Inductive Methods (Magnetic Field Testing) ... 54
5.9.3 Cover Meters 55
5.9.4 Magnetic Particle Inspection 57
5.9.5 Steel Fiber Content 60
5.10 Holography 60
5.11 Leak Testing Method 61
5.12 Longitudinal Stress Waves 62
5.13 Maturity Concept 63
5.14 Microwave Inspection 65
5.15 Middle Ordinate Method 665.16 Moisture Detection Methods 67
5.16.1 Electrical Resistance Probe 67
5.16.2 Capacitance Instruments 69
5.16.3 Nuclear Meter 70
5.16.4 Infrared Thermography 72
5.17 Nuclear Density Meter 72
5.18 Paint Inspection Gages 73
5.18.1 Tooke Gage 73
5.18.2 Pencil Test 73
5.18.3 Magnetic Thickness Gages 74
5.18.3.1 Magnetic Pull-Off Gage 74
5.18.3.2 Magnetic Flux Gage 74
5.18.4 Wet Film Thickness 75
5.18.4.1 Interchemical Wet Film Thickness Gage 75
5.18.4.2 Pfung Gage 76
5.18.4.3 Notch Gage 76
5.19 Pin Hole Detector 77
5 . 20 Point-Load Test 78
5.21 Probe Penetration Method 79
5.22 Proof Load Testing 825.23 Pull-Off Test 82
5.24 Radar 845.25 Radioactive Methods 85
vi
TABLE OF CONTENTS (Continued)Page
5.25.1 Radiography 86
5.25.2 X-ray Radiography 86
5.25.3 Gamma Radiography 87
5.25.4 X-ray Fluorescence Analyzer 90
5.26 Seismic Testing 91
5 .27 Soil Exploration 92
5.27.1 Cone Penetration Test 92
5.27.2 Helical Probes 92
5.27.3 Standard Penetration Test 93
5.28 Surface Hardness Testing 94
5.28.1 Static Indentation Tests 94
5.28.2 Rebound Hammer Method 96
5.29 Thermal Inspection Methods 99
5.29.1 Infrared Thermography 101
5.29.2 Envelope Thermal Testing Unit 1045.29.3 Heat Flow Meter 105
5.29.4 Portable Calorimeter 106
5.29.5 Spot Radiometer 107
5 .30 Ultrasonic Pulse Methods 109
5.30.1 Ultrasonic Pulse Velocity 110
5.30.2 Ultrasonic Pulse Echo 113
5.31 Uplift Resistance 115
5.32 Visual Inspection 116
5.32.1 Optical Magnification 1165.32.2 Fiberscope 117
5.32.3 Liquid Penetrant Inspection 118
5.33 Water Permeability of Masonry Walls 120
5.34 Combinations of Nondestructive Evaluation Methods 121
6. SUMMARY 124
7. ACKNOWLEDGMENTS 125
8. REFERENCES 126
vii
TABLE OF CONTENTS (Continued)
Page
APPENDIX A. REVIEW OF NAVY GUIDE SPECIFICATIONS A-1
APPENDIX B. REVIEWED NAVY GUIDE SPECIFICATIONS THAT CONTAIN REQUIREDNDE TESTS B-1
APPENDIX C. LISTS OF REVIEWED NCEL TECHDATA SHEETS AND NCEL TECHNICALAND RESEARCH REPORTS THAT CONTAIN NDE METHODS C-1
APPENDIX D. ASTM STANDARDS FOR NDE METHODS FOR CONSTRUCTION MATERIALSAND BUILDING COMPONENTS D-I
vlil
tiST OF TABLES
Page
Table 1. NDE Methods for Inspecting Hardened Concrete 15
Table 2. NDE Methods for Inspecting Masonry and Masonry Materials ... 16
Table 3. NDE Methods for Inspecting Wood and Lumber 16
Table 4. NDE Method for Inspecting Metals 17
Table 5. NDE Methods for Inspecting Roofing Systems 18
Table 6. NDE Methods for Inspecting Paints and Coatings 19
Table 7. NDE Methods for Inspecting Soils 20
Table 8 . NDE Methods for Inspecting Sealants 20
Table 9, NDE Methods for Inspecting Thermal Insulation 21
Table 10. NDE Methods for Inspecting the Building Envelope 22
Table 11. NDE Methods for Inspecting Pipe and Drainage Systems 23
Table 12. NDE Methods for Inspecting, Heating, Ventilation, andAir Conditioning Systems 23
Table 13. Operation, Principles, and Applications of Commonly Used andPotential NDE Methods for Inspection of Building Materialsand Systems 24
Table 14 . Gamma Ray Sources 88
Table 15. Pulse Velocities in Concrete Ill
Table A. Review of Navy Guide Specifications A-2
Table B. Reviewed Navy Guide Specifications that Contain RequiredNDE Tests B-2
Table CI. List of Reviewed NCEL Techdata Sheets that Contain NDEMethods C-2
Table C2. List of Reviewed NCEL Technical and Research Reports thatContain NDE Methods * C-3
Table Dl . ASTM Standards for NDE Methods for Concrete D-2
Table D2. ASTM Standards for NDE Methods for Construction Materialsand Building Components D-3
~^ ix
1. INTRODUCTION
1 . 1 Background
Nondestructive evaluation (NDE) methods offer significant advantages over
traditional laboratory and field methods for determining the properties of
construction materials, especially in the making of in situ measurements of
these materials. There are many NDE methods and they may be used in all phases
of the construction and service cycle of buildings and other structures,
beginning with the construction phase and continuing through the maintenance,
repair, and rehabilitation phases. Currently used NDE methods and other
methods based on emerging and advanced technology may be used in the main-
tenance, repair, and condition assessment of buildings and facilities. In
addition, NDE methods may serve as an Important tool in building diagnostics
to assist in assessment of their condition because of construction deficiences
and changes in occupancy or mission or materials properties.
The National Bureau of Standards (NBS) completed a study in 1982 for the
U.S. Army Construction Engineering Research Laboratory (CERL) entitled,
" In-Place Nondestructive Evaluation Methods for Quality Assurance of Building
Materials" [1]^. Since then, advances in the state-of-the-art of some NDE
methods have taken place. The Naval Civil Engineering Laboratory (NCEL) and
the Naval Facilities Engineering Command (NAVFAC) asked NBS to review current
Navy NDE practices and to update the 1982 study [1]. This report is a revision
of the earlier study and includes additions to the tables of NDE methods
and to the text which describes the NDE methods. The list of ASTM standards for
•• Figures in brackets indicate references listed in Section 8.
1
isuti. methods applicable to building materials is revised and updated. Based on
reports and documents provided by NCEL and NAVFAC, a review of current Navy
NDE practices is presented along with a brief summary of NDE studies.
1.2 Objective
The objectives of this study are: (1) to update the 1982 NBS study,
" In-Place Nondestructive Evaluation Methods for Quality Assurance of Building
Materials" [1] by identifying new NDE methods which can be used for condition
assessment and to help to assure the quality and uniformity of in-place
construction materials; and (2) to review current Navy practices relative to
the use of NDE methods in the construction and service cycle of buildings and
other structures.
1.3 Scope
Since completion of the 1982 NBS study [1], there have been advances in
the state-of-the-art of some NDE methods. These advances in NDE methods for
construction materials and condition assessment of buildings and structures
have been included in this report. The information presented in this report
was obtained from the literature and from those knowledgeable in the field.
The 1982 NBS study [1] was the source for a considerable portion of the
information. No laboratory research was performed during the course of this
study. Discussions were held with members of technical committees which cover
the selection and use of NDE methods and with researchers who have evaluated
some NDE methods. ASTM standards were reviewed to identify those applicable
for NDE methods which may be used for the in situ evaluation of construction
materials and condition assessment of building components and structures.
Emerging NDE methods that have application to the diagnostic needs
of the Navy were identified. These are considered to be methods which recently
have been demonstrated to be sufficiently reliable to either be used in the
field without further development or which need minimal further development.
Promising advanced NDE methods which require further research and development
before they are ready for routine use were also identified. Needed research
in the area of NDE methods for construction applications of the Navy was
addressed.
Current Navy practices relative to the use of NDE methods in the
construction and condition assessment of buildings and other structures were
reviewed. Information for this review was obtained from Navy reports and
documents provided by NAVFAC and NCEL. The review of Navy practices regarding
NDE methods included information from reports dealing with their use, evaluation,
and research.
Over 200 Navy Guide Specifications were examined for required tests, both
NDE and destructive, of in situ building materials and components. A list of
the required NDE tests included in the Navy Guide Specifications was compiled.
2. REVIEW OF CURRENT NDE NAVY PRACTICES
2.1 Guide Specifications
NAVFAC provided NBS with 239 Guide Specifications for review with regard
to NDE in situ tests (field tests) of building materials and components. The
list of Guide Specifications and the corresponding required field tests, both
NDE and destructive, are given in Appendix A. NDE tests were required in 29
of the reviewed Navy Guide Specifications. A list of these 29 Guide
Specifications along with the in situ NDE tests are presented in Appendix B.
2.2 Summary of NDE Practices Obtained from Brief Discussions with NAVFACPersonnel
Discussions with NAVFAC personnel indicated that the Engineering and
Design staff are involved with limited and special problems with buildings and
structures where NDE methods are used. As an example, with regard to condition
assessment of concrete, cover meters are used to determine rebar location and
thickness of concrete cover. The penetration probe and rebound hammer are
also used to assess concrete properties. Load tests of buildings and structures
are conducted. In these tests American Concrete Institute (ACI) recommendations
are followed for concrete structures. Strain gages and deflection gages are
used for making measurements. It was reported that NCEL has equipment to detect
vibrations in buildings that have been subjected to earthquakes and contain
cracks in order to assist in the assessment of the condition of these buildings.
In addition, NCEL has instrumented new buildings in order to obtain base line
data of the properties of these buildings.
Leak detectors are used to detect leaks in pipe lines, including joints.
Methods used have included ultrasonics and detection of gas. Welds are
inspected by different methods including liquid penetrant inspection. It is
desirable to determine the condition of underground pipe lines and to predict
their service life. Included in the condition of underground pipes is the
number of leaks (water, gas, steam, etc.) and the size and wall thickness
of the pipes. It was reported that the Naval Research Laboratory (NRL) has
developed methods for determining delamination of honeycomb panels using ultra-
sonic and acoustic emission techniques. It was also reported that NCEL has a
device for determining locations where corrosion is occuring in precast and
prestressed concrete piles. Underwater piles are difficult to inspect. The
Navy's Chesapeake Division is involved in the evaluation of underwater
structures.
NAVFAC has a program aimed at development of condition assessment
Standards for buildings, structures and utilities, such as PAVER (pavements)
and ROOFER (roofs) in order to provide consistency in inspections. It is
difficult to make usable technology available for condition assessment of
these facilities. Pavement inspections are mostly visual but ultrasonic and
radar techniques are used. These NDE methods are generally applicable at
specific locations. Skid resistance measurements are made on runways,
2,3 Review of NDE Needed and Presently Used Methods Based on the Resultsof Responses to NCEL Questionnaires
In the fall of 1985 the NCEL sent questionnaires to Navy Public Works
Centers regarding their needs and practices to assess nondestructively the
quality of new construction and the condition of existing shore facilities.
Eight of the responses that were received from Navy Public Works Centers were
reviewed and a brief summary of the reported needs for Inspections and
assessment of the quality of new construction and the condition of existing
facilities are presented along with presently used NDE methods.
2.3.1 List of Reported Needed NDE Methods
• early Identification of problems with water front structures
• under-pler construction, methods for condition assessment and maintainingexisting systems
• underwater inspection of wharves, piers, and underwater structures(currently divers must visually Inspect pilings and sheet piles)
• underwater TV camera for Inspection of piling underneath piers
• assessment of condition of underground heat distribution systems
• leak location detector for heating distribution systems
• extent of corrosion in piping, pumps and reservoirs
• location of underground piping
• detection of underground piping leaks
• remote monitoring of systems performance and condition of componentsof facilities
• condition of underground utility systems including leak detection(steam, electrical, natural gas, water, fuel)
• portable metering of utilities performance as a diagnostic tool inutilities management and maintenance
• moisture detection device for inspection of built-up roofs
• condition of cast iron piping and earthen dams
• inspection of underground storm drain and sewer lines
• methods for determining condition of underground storage tanks and forleak detection
• device to check for faults in power line insulation
• device to identify faults in pipe walls
• means for checking energy efficiency of building insulation (possible solutionIs the use of an infrared camera)
• infrared scanner to Inspect insulated heating pipe
• early detection of minor trouble with large pieces of dynamic equipment
pavement analysis equipment for early defect detection
detection of worn or thin Insulation on steam, chill water, and otherpipelines
determination of condition of transformers
development of an exterior painting condition assessment computer program
monitor condition of major transformers
condition assessment for wood buildings including termite damage of
wood components
training program in diagnostics and condition assessment technology
3.2 List of Reported Presently Used NDE Methods
location of underground piping leaks (methods used include Injectionof helium and SF5 into compressed air systems to pinpoint leaks)
leak location detector for heating distribution systems
infrared scanning of polelines , switchgear, electrical equipment,electrical panels, and steam traps to Identify anomalous sources of heat
infrared scanning of building exteriors to identify heat leakage
nuclear meter for detection of moisture in roof surveys
electrical resistance probe for detecting moisture in walls, roofs, andslabs of buildings
ultrasonic testing to determine the wall thickness of condensate pipelines and their condition while the line is still in service
ultrasonic testing to measure the wall thickness of metal pipes andl:hickness of fuel storage tank siding and floor
examination of sewer lines with a TV camera to determine theircondition (visual inspection with remote monitor)
transformer condition can be judged from an analysis of its insulatingfluid
extent of wood decay and deterioration by puncturing with an ice pickand tapping with a hammer
extent of termite damage using an audio scope.
2.4 Navy NDE Publications
Some Navy publications dealing with the inspection of buildings, design
criteria, research, and relevant NDE methods which were provided by NCEL
and NAVFAC were reviewed with regard to current Navy practices, evaluation
methods, and recent research. The manual, "Inspection of Shore Facilities,"
Volume 2, NAVFAC MO-322 , May 1978, provides maintenance inspection/service
checklists for buildings, grounds, utility plants, utility and distribution
systems, and components of Navy shore facilities. It provides a guide for
developing and implementing an effective and efficient preventive inspection
system. Only visual inspections are listed in this manual. Another Navy
manual "Engineering and Design Criteria for Navy Facilities", NAVFAC F-34
,
August 1985, lists specifications and standards relative to Navy facilities
which are issued by government agencies (public sector) and private sector
organizations. This design manual refers to nondestructive evaluation of butt
welds in crane and railroad rails.
Some NCEL Techdata Sheets containing information about NDE inspections or
the use of NDE equipment which were provided by NCEL were reviewed. Techdata
Sheets usually give a brief explanation of an NDE method or a brief description
of NDE equipment and its use. In many cases the Techdata Sheets are based on
a technical or research report which gives background data, research results,
and details pertinent to the NDE methods or equipment. A list of the NCEL
Techdata Sheets that were reviewed is given in Appendix C. The following
examples are given regarding NDE methods contained in the Techdata Sheets
:
• Inspection of painting• Measuring water permeability of masonry walls• Leak detection in pipelines• Infrared thermometers for roofing inspections• Use of penetration probe test system for strength evaluationof concrete in Naval construction
• Problems with underwater ultrasonic inspection• Inspection methods for wood fender and bearing piles• Locating and tracing buried metallic pipeline
Many different NDE methods are included in the Techdata Sheets. Most of
the NDE methods are listed in the tables in Section 4 of this report and
described in Section 5.
Some NCEL technical and research reports provided by NCEL and NAVFAC were
reviewed with regard to NDE methods and equipment. These reviewed reports are
also listed in Appendix C. They contain information about many types of NDE
methods and in many cases research results, assessments of NDE methods,
comparisons of NDE methods, the significance of the methods, their accuracy
and reliability, and their use in the field are presented. Examples of the
information regarding NDE methods in the technical and research reports include
the following:
• Pulse echo ultrasonic testing has been investigated for measuring thecorroded metal thickness of steel piles. Results of ultrasonicevaluations have been compared to resistance probing and coring forcondition assessment of wooden waterftont structures.
• Information is available about instructions for inspection andtesting of railroad and ground level trackage. NDE methods used areultrasonic inspection, optical instrument surveying, electromechanicalrelative displacement measurements, inertial displacement measuringtransducer, proximity sensors, and laser-based level devices.
• Assessment of cables and wire rope is carried out using alternatingcurrent to produce an electromagnetic field to detect loss ofmetallic areas in the wire rope. For smaller wire rope, a portableNDE device that employs an audible signal detected by a head setcan indicate flaws.
• Moisture can be detected in roofing systems based on surveys usingnuclear moisture meters, infrared thermography, and capacitancemeters.
With regard to underground utility lines, an NCEL state-of-the-artsurvey found no existing techniques capable of nondestructivecondition assessment. Utility companies and water distributionagencies use sonic detectors for leak detection. It was reportedthat none of the six techniques investigated, acoustic emission,radiography, sonic , ultrasonic , eddy current, and magnetic flux, weresuitable for Navy use on buried pipelines. Ground penetrating radarwas investigated as a method for detecting underground utilitylines
.
Extensive internal damage can be detected in underwater timberpiles by an impact hammer sounding technique. The pile is struckwith a hammer and damage is assessed from the acoustic response.
Small portable infrared specti'ophotometers that were introducedcommercially for field analysis of gases and liquids were modifiedin order that organic solid materials could be identified and analyzed,This modified portable instrument showed promise that organicconstruction materials (paints, plastics, insulations, etc.) couldbe identified in the field. This could help provide for propermaintenance. It also could help ensure that specified materialswere used by the contractor, and deterioration of protectivecoatings could be detected.
10
3. NDE METHODS
The NDE methods are listed in Tables 1 through 13 in Section 4 and
descriptions of the NDE methods are given in Section 5. The tables and
descriptions of the NDE methods have been updated from the previously
mentioned 1982 NBS study [1]. A considerable portion of the information in
the present report was taken from the previous study. It is noted that
some in situ NDE tests may or may not cause minor damage to materials or
buildings components. An example of an instrument that may cause minor
damage is an electrical resistance probe to determine the moisture content
of insulation.
The NDE tables in Section A list key properties of commonly used building
materials and NDE methods for estimating the level of these properties or
characterizing the materials. Operation, principles, and applications of the
NDE methods are outlined in Table 13, These tables are intended to familiarize
those personnel involved with quality assurance and condition assessment of
building materials and components with NDE methods, and to help in the selection
of appropriate methods. More detailed information about the NDE methods or
descriptions of the methods are provided in Section 5. Appendix D lists
standard test procedures which the American Society for Testing and Materials
(ASTM) has issued for some NDE methods covered in this report.
To use the information in this report most effectively, begin with
Tables 1 through 12. If, for example, the quality and uniformity of in-place
concrete seem questionable, further inspection could be justified. The options
for inspection of hardened concrete are given in Table 1. Concrete properties
are given in the first column and appropriate NDE methods for each property
are found in the second column. For the example given, four methods are listed
11
for determining the general quality and uniformity of hardened concrete:
(1) penetration probe, (2) rebound hammer, (3) ultrasonic pulse velocity, and
(4) radiography (gamma). The methods are not ranked; the table simply provides
a list of applicable methods. To help decide which of these methods would be
appropriate for a specific application (considering factors such as equipment
availability, cost, and information obtained), consult Table 13. For more
information before selecting any of the four methods, refer to Section 5 which
gives detailed information about the NDE methods.
The cross reference features of the tables can be used in the same way for
information about other recommended NDE methods.
Note that the information in this report is not intended to supersede
existing guide specifications. In cases of conflict, the guide specifications
are to be followed.
12
4. NDE TABLES
4.1 Building Materials, Components, and Systems
Major building materials, their important properties, and NDE methods for
estimating the value of these properties or for characterizing the materials
are given in Tables 1 through 9. Materials considered are:
Table No. Building Material
1 Concrete2 Masonry materials3 Wood and lumber4 Metals5 Roofing6 Paints and coatings7 Soils8 Sealants9 Thermal insulation
The following building components and systems are covered in Tables 10 through
12:
Table No. Components and Systems
10 Building envelope11 Pipe and drainage systems12 Heating, ventilation, and
air conditioning systems
In Tables 10-12, the main performance requirements are listed, and NDE
methods intended for determining if these requirements are being met are
also listed.
The selection of the building materials, components, and systems addressed
in this report was largely based on considerations of: (1) the amount of
their use; (2) the frequency and severity of problems caused by deficiencies
in their quality, uniformity, or performance; and (3) the value of using NDE
methods to inspect the material, component, or system. As an obvious example,
NDE inspection is not necessary to determine that a glass window is broken,
13
while locating reinforcing steel in concrete is more readily done by NDE
inspection than by coring. Researchers from the NBS Center for Building
Technology and from the NBS Office of Nondestructive Evaluation of the National
Bureau of Standards, and personnel of the U.S. Army Corps of Engineers
collaborated in the selection process in the earlier NBS study [1],
In Tables 1 through 12, the column headed "Currently Recommended NDE
Methods" lists ways of testing various material properties. These tests are
commonly used, and their limitations are well known. The column headed
"Potential NDE Methods" lists NDE methods that may prove useful, but are
still being assessed. In some cases, suitable NDE methods are not available,
as an example, for the inspection of the bond between a sealant and its
substrate (Table 8).
4.2 Survey of NDE Methods
The operation, principles, and applications of recommended NDE methods
for inspecting building materials are outlined in Table 13. Self-explanatory
NDE methods such as the use of rulers and visual inspection methods are not
included in Tables 1 through 12.
Once construction inspectors and those involved in condition assessment
become familiar with the advantages of using NDE, they may wish either to train
people in their own organizations, or to obtain help from persons knowledgeable
about NDE inspections. Comments on the expertise the user needs, equipment
costs, and safety requirements are intended to help potential users decide
which path to follow.
14
Table 1
NDE Methods for Inspecting Hardened Concrete
Property
Strength
Currently Reconmended NDE Methods
Method
Penetration Probe
Rebound HammerCast-ln-place pullout
Maturity concept
Locationin Report ^
5.21
5.28.5.7
5.13
Potential NDE Methods
Locationin Report ^
5.30.
5.205.235.6
Method
Ultrasonic pulse velocityPoint-load test
Pull-off testBreak-off method
General qualityand uniformity
Penetration Probe 5.21
Rebound Hammer 5.26.2Ultrasonic pulse velocity 5.30.1
Radiography 5.25.1
5.30.25.1A5.24
5.5
Ultrasonic pulse echoMicrowavesRadarAir permeability
Thickness
Density RadiographyUltrasonic pulse velocity
5.25.35.30.1
5.1A5.25.35.30
5.9.15.25.1
5.17
Microwaves (radar)Gamma radiographyUltrasonic pulse,velocity and echo
Eddy currentRadiography
Air content 5.17 Neutron density gage
Stiffness Ultrasonic pulse velocity 5.30.1
Surface texture Visual 5.32 5.14 Microwaves
Neutron density gage
Rebar depthand position
Cover meterRadiography
5.9.35.25.3
5.145.30.
5.24
Microwaves (radar)Ultrasonic pulse echoRadar
Corrosion state Visualof reinforcing Electrical potentialsteel measurement
5.325.8
Presence of Acoustic impact 5.2subsurface voids Ultrasonic pulse echo 5.30.2or delamlnatlons Radiography 5.25.3
Ultrasonic pulse velocity 5.30.1
5.29.15.24
Infrared thermographyRadar
Moisture contentand moisturepenetration
5.145.16.3
MicrowavesNuclear
Cement content 5.16.3 Nuclear
Durability Visual 5.32
Steel fibercontent
5.9.5 Electromagnetic method
Critical andrupture loads(crackabilltyfactor)
5.1
5.30.1Acoustic emissionUltrasonic pulse velocity
^ Numbers in this column refer to NDE Method Nos. described in Section 5 and listed in Table 13.
15
Table 2
NDE Methods for Inspecclog Masonry and Masonry Materials
Property
Integrity of
masonry
Qirrently Reco—ended NDE Methods
Mathod
LocationId Report *
4cou«tic lapact 5.2
Radiography J.25.3Probe holes with 5.32.2
fiberscopeDltraaonlc pulse velocity 5.30.1
Potential NDE Methods
LocationIn Report *
5.30.25.145.24
NDEHethod
Ultrasonic pulie echoMicrowavesRadar
Thickness of
asonryProbe holes 5.32 5.9.1
5.30.25.25.1
Eddy currentUltrasonic pulse echoRadiography
Reinforcing steel
(location and
size)
Cover aeterRadiography
5.9.35.25.3
5.30.15.145.25.1
Ultrasonic pulse echoMicrowavesRadiography
Presence of Probe holes 5.32
inner grout Radiography 5.25.3Acoustic iapact 5.2
Ultrasonic pulse velocity 5.30.1
5.30.2 Ultrasonic pulse echo
Moisture contentand moisturepenetrstion
Moisture aeter-electrical resistance
5.16.1 5.145.16.3
MicrowavesMoisture aeter-nuclear
Presence of Acoustic iapact 5.2
delaninations Radiography 5.25.3
Ultrasonic pulse velocity 5.30.1
5.30.25.29.1
5.25.2
Ultrasonic pulse echoTheraal inspection(theraography)Radiography
Waterperneablllty of
coated masonry
5.33 Water peraeability
* Numbers in this column refer to NDE Method Nos. described in Section 5 and listed in Table 13.
Table 3
NDE Methods for Inspecting Wood and Lumber
Property
Currently Reconaended NDE Methods
Method
Integrity and
general quality(including grade,aechanlcalproperties, andassessment of
insect, mechanicaland decay damage*
Visual grading by
certified grader*Proof loading
Locationin Report *
5.22
Potential NDE Methods
Locationin Report *
5.1
5.30
5.25.1
5.155.12
Method
Acoustic emissionUltrasonic pulse velocityand echoRadiographyPenetration hammerMiddle ordinate methodLongitudinal stress waves
Density Ultasonlc pulse velocity 5.30.15.25.15.12
Penetration hammerRadiographyNuclear density aeter
Moisture content Electric resistance 5.16.1probeCapacitance Instrument 5.16.2
5.16.3 Nuclear aoisture aeterSurface hygrometersMicrowaves absorption meter
Adhesive bondfor laminatedwood
5.25.29.1
5.25.1
Acoustic aethodsTheraal inspection
(theraography)Radiography
Dimensions Rulers, calipers,electronic measuringdevices**
• Numbers in this column refere to NDE Method Nos. described in Section 5 and listed in Table 13.
• Perform on luaber before use; this method not described in Table 13.** Because of their simplicity, methods not described in Table 13.
16
Table A
NDE Methods for Inspecting Metals
Currently Recommended NDE Methods
Property Method
LocationIn Report"
Potential NDE Methods
LocationIn Report ' Method
A. Structural Metals
Presence and
location In
other materials
Radiography 5.25.3
Magnetic devicesCover meter 5.9.3
Eddy current devices 5.9.1
Probe holes with 5.32.2
fiberscope
5.30.2 Ultrasonic pulse echo
Type of metal Magnetic devicesChemical spot testing*Spark testing*Color*X-ray fluorescenceanalyzer
Electromagnetic methods
5.25.4
5.9
Cracks, flaws Radiography 5.25.3Ultrasonic pulse echo 5.30.2Magnetic particle 5.9.4Liquid penetrant 5.32.3Eddy current 5.9.1
5.105.145.29.1
HolographyMicrowaveThermal inspection
Corrosioncondition
Electrical potentialmeasurement
5.8 5.9.15.30.2
Eddy currentUltrasonic pulse echo
Loose boltsrivets and screws
Visual 5.32 5.2 Acoustic Impact
B. Weld Defects
Cracks Ultrasonic pulse echo 5.30.2Radiography 5.25.3Magnetic particle 5.9.4Liquid penetrant 5.32.3
Lack of fusion Ultrasonic pulse echoRadiography
5.30.25.25.3
5.9.4 Magnetic particle
Slag inclusion RadiographyMagnetic particle
5.25.35.9.4
5.30.2 Ultrasonic pulse echo
Porosity Radiography 5.25.3 5.32.35.30.2
Liquid penetrantUltrasonic pulse echo
Incompletepenetration
RadiographyUltrasonic pulse echo
5.25.35.30.2
C. Pipes and Tanks
Type of metal See Structural Metals, above
Wall thickness Eddy current 5.9.1Ultrasonic pulse echo 5.30.2
Leaks andcontinuity
Leak testing 5.11
Corrosioncondition
Electrical potential 5.8measurements
5.9.15.30.2
Eddy currentUltrasonic pulse echo
a Numbers In this Column refer to NDE Method Nos. described in Section 5 and listed in Table 13.
* For more Information on these methods see Reference [2).
17
Table 5
NDE Methods for Inspecting Roofing Systems
Property
Composition
Currently Recommended NDE Methods
MethodLocationin Report ^
Potential NDE Methods
Locationin Report^ Method
Cores* — laboratory analysis,specific gravity, solvent,odor, and chemical tests todistinguish between asphaltand coal tar pitch
Moisture content
of insulationThermal inspection 5 16 .It
(thermography)Nuclear moisture 5 16 3
meterCapacitance 5 16 ,2
Electrical resistance 5 16 1
probe
5.14 Microwaves
Permeability of
roofing systemFlood or pond water on
roof followed by usingmethods to measuremoisture content of
Insulation
Seam integrity(single-ply)
5,29.15.30.2
Infrared thermographyUltrasonic pulse echo
Slope and drains Flood or pond water on roof
Self supportingunder design loads
Proof loading 5.22Wind uplift test (can 5.31be destructive)
Uplift resistance Negative pressure 5.31
a Numbers in this column refer to NDE Method Nos. described in Section 5 and listed in Table 13.
Destructive method
18
Table 6
NDE Methods for Inspecting Paints and Coatings
Currently Recommended NDE Methods
Property MethodLocationIn Report^
Number and
type of layers
Tooke Gage 5.18.1
Dry film thickness
Metal
:
1
.
Magnetic pull-off gage2. Magnetic flux gage3. Eddy current4. Tooke Gage
5.18.3.15.18.3.25.9.1
5.18.1
Potential NDE Methods
LocationIn Report " Method
Wood: Tooke Gage 5.18.1
Wet film thickness 1. Interchemlcal gage2. Pfund gage3. Notch gage
5.18.4.15.18.4.25.18.4.3
Hardness Pencil test 5.18.2
Integrity(Pin holes)
Metal:
Wood:
Pin hole (holiday)detector
Field microscope
5.19
5.32.1
Bond to
subsurface
5.29.1
Adhesion testerScratch adhesion testThermal inspection(thermography)
Surfacepreparation
5.18.15.32.1
Tooke gageField microscope
General qualitycolor, reflectance,blistering, etc.
5.29.1
Photography — comparisonwith standard
Measurement of reflectivityThermal inspection(thermography)
8 Numbers in this column refer to NDE Method Nos. described In Section 5 and listed in Table 13.
19
Table 7
NDE Methods for Incpectlng Soils
Property
Adequate drainage
Currently Recoanended NDE Methdos
Method
Visual check of gradeand topography*
LocationIn Report*
Potential WDE Methods
LocationIn Report •_ Method
Adequacy ofbackfill
5.14 Microwave to detectcavities In backfill
Density andcompaction
Seismic testing (wavepropagation)
Nuclear density meter
5.26
5.17
5.27.2 Helical probes
Moisture contents
Detect cavities
Nuclear moisture meter 5.16.3 5.16.1
S.16.4
5.145.26
5.29.1
Electrical resistanceprobebtfrared thermography
Stiffness 5.26 Seismic testing (wavepropagation)
Permeability 5.16.4 Infrared thermography
Strength Standard penetration test
Cone penetration test5.27.35.27.1
5.27.2 Helical probes
MicrowaveSeismic testing (wavepropagation)bifrared thermography
° Numbers in this column refer to NDE Method Nos. described In Section 5 and listed In Table 13.
* Because of its simplicity, method not described in Table 13.
Table 8
NDE Methods for Inspecting Sealants
Property
Currently Recoanended NDE Methods
MethodLocationIn Report*
Potential NDE Methods
LocationIn Report* Method
Water permeability(infiltration)
Electrical resistancemeterCapacitance Instrument
5.16.1
5.16.2
General quality andworkmanship
Move water Jet up thebuilding wall (from bottomto top) and observe waterinfiltration — use methodsgiven for testing for waterpermeability
5.16.15.16.2
Bond to substrate*
B Numbers in this column refer to NDE Methods Nos. described In Section 5 and listed In Table 13.
* Destructive laboratory tests are available.
20
Table 9
NDE Methods for Inspecting Thermal Insulation
Property
Currently Recommended NDE Methods Potential NDE Methods
Method In Report * in Report " Method
Performance Thermal Inspection(Infrared thermography)
5.29.1 5.29.55.29,35.29.45.29.2
Spot radiometerBeat flow meterPortable calorimeterEnvelope thermal testingunit
Location Thermal Inspection 5.29.1(Infrared thermography)Fiberscope 5.32.2
5.29.55.29.3
Spot radiometerHeat flow meter
Moisture contents 5.16.25.16.15.29
Capacitance instrumentElectrical resistance meterThermal inspection
Corroslveness Measure electrical potentialof metals In contact withinsulation
5.8
B Numbers in this column refer to NDE Method Nos. described in Section 5 and listed in Table 13.
21
Table 10
NDE Methods for Inspecting the Building Envelope
Cjrrently Recommended NDE Methods Potential NDE Methods
Component Main Performance Location Locationor System Requirements Method in Report" in Report" Method
Walls and No penetration 5.16.2 Capacitance
Ceilings by rain water5.32.25.16.35.16.1
instrumentationFiber scopeNuclear meterResistance probe
Retard heat Thermal 5.29 5.29.1 Thermal inspectiontransmission Inspection
5.29.55.29.35.29.45.29.2
(thermography)Spot radiometerHeat flow meterPortable calorimeterEnvelope thermal testingunit
Building envelope Air Infiltration 5.
A
5.4.1 Tracer gas
tightness measurement 5.4.4 Smoke tracer
Infrared thermography 5.29.1 5.4.3 Acoustic method
Foundation Supports buildingandBasement Prevents
settlementVisual cracksurvey
Level readings —change withelapsed time*
Strain gagebuttons on cracks*
Photographicrecording of crackswith elapsed time*
Prevents upward Moslture meter 5.16movement of moisture
Prevents Visual and/or 5.32basement slab level readings -
movement change withelapsed time*
Roof No penetrationby rain water
Nuclear moisturemeterThermal inspection(thermography)
5.16.3
5.16.4
5.16.2 Capacitance instrument
Self-supporting Proof loading 5.22under design loads
Retard heat Thermal inspection 5.16.4transmitting (thermography)
Floor Levelness Level readings —change withelapsed time*Carpenter's level*
Supports design Proof loading 5.22service loadsJoining details 5.25.3 Radiographyand construction 5.32.2 Fiberscopepractices andmaterials
" Numbers in this column refer to NDE Methods Nos. described in Section 5 and listed in Table 13.
* Self-explanatory; not described in Table 13.
12
PerformanceRequirements
Does not leak
Table 11
NDE Methods for Inspecting Pipe and Drainage Systems
Currently Reconmiended NDE Methods
Method
Leak testing
LocationIn Report ^
5.11
Potential NDE Methods
LocationIn Report ^ Method
Proper flow rate Measure volume of
water flowing duringtime Interval*
Flow meterconnectedto outlet
Proper flowpressure
Hydrostaticpressure gage
Dielectric joints
between dissimilarmetals
Measurement of
electrical resistanceacross joint*
5.32.2 Inspection by
fiberscope
Prevention of backflow of gases
Direct measurementof water in trap*
Determinationof pressure of
proper component
^ Numbers in this column refer to NDE Methods Nob. described in Section 5 and listed in Table 13.
* Self-explanatory; not described in Table 13.
PerformanceRequirements
Table 12
NDE Methods for Inspecting Heating, Ventilation, and Air Conditioning Systems
Currently Recommended NDE Methods Potential NDE Methods
Proper air
flow level(ventilation)
MethodLocationin Report ^
Air flowmeasurement(tracer gas)
5.4.1
Locationin Report ^
5.3.1
Method
Pltot traverse
Air ductsproperly sealed
Leakdetection*
5.4.3 Sound Amplification5.32.2 Fiberscope5.4.4 Smoke tracer
8 Numbers in this column refer to NDE Methods Nos. described in Section 5 and listed in Table 13.
* Self-explanatory; not described in Table 13.
23
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36
5. DESCRIPTION OF NDE METHODS
The descriptions of the NDE methods generally include information about the
methods, descriptions of the methods, applications of the methods, and the
advantages and limitations in using the methods. In some cases, other
information about the NDE methods is presented such as reliability of a method
and calibration of NDE equipment. In other cases, however, because information
was not available in the literature some information such as advantages and
limitations of the NDE methods may not be included in this section of the
report.
5.1 Acoustic Emission Method
In this method, stress waves originating within the test object are
detected by surface transducers [2]. The acoustic waves result from the
sudden release of stored strain energy when either pre-existing or newly
created flaws propagate under the action of an applied stress field. The
types of flaw propagation that can be detected include dislocation movement
in metals and microcrack growth in metals or brittle solids such as concrete.
Thus, acoustic emission can indicate the start of mechanical failure —
i.e., yielding or fracture. The test object must undergo stress so that
flaws will appear or propagate; static flaws are not detected by acoustic
emission.
Description of Method
Acoustic emission testing is a passive technique; only an acoustic wave
detection instrument is required. The acoustic waves, which may have a
frequency range from audible to ultrasonic, are detected by piezoelectric
transducers attached to the surface of the test object. The existence of
37
flaw growth can be detected by a transducer anywhere on the test object
(provided that there is enough wave amplitude to be detected). Thus, the
location of transducers relative to pre-existing flaws is not critical
in this method unless it is required to locate the flaw. The transducers
generally detect waves in the frequency range of 50 kHz to 10 MHz [2], Detected
signals are amplified; the amount of necessary amplification depends on the
source of the acoustic emission. Signals from dislocation movement require
greater amplification than signals from microcrack propagation. After
amplification, the acoustic emission activity is processed and displayed.
The most useful displays are the rate of acoustic emission events (detected
signals), or the cumulative number of events plotted as a function of a
pertinent parameter, such as time, applied load, or number of load cycles.
Growth of microcacks as small as 10~^ in. (2.5 x 10~^ mm) can be detected,
while the minimum static flaw detectable by ultrasonic or radiographic methods
is about 0.001 in. (0.025 mm).
Applications
The method has been used to monitor the in-service behavior of pressure
vessels (including nuclear reactors), to detect the onset of rapid crack
propagation under fatigue loading or caused by stress corrosion, and to
monitor the response of systems to proof-load tests. Because acoustic
emissions give forewarning of ultimate failure, the technique can be used to
signal when loads should be reduced to prevent total failure. By using both
multiple pickup of acoustic signals with transducers at different locations
and electronic data processing, regions of high acoustic emission activity
can be pinpointed, and a critical "weak link" in the system located,
38
Advantages
The most significant advantage of the acoustic emission method is that it
gives the response of the total structure or system (in "as-built" condition)
to applied loads. By observing the acoustic emission activity as loads are
applied, one can find the extent of internal material degradation (yielding
or fracture) as a function of load. Generally, the stage of incipient failure
can be determined because this is usually accompanied by a rise in the acoustic
emission rate and a rapid increase in the cumulative number of emissions.
Limitations
A major difficulty in interpreting acoustic emission results is the
separation of signals caused by the loading system or by microscopic slippage
at joints in the test object from the signals produced by flaw propagation
in the material. Users of the technique must be aware of all the possible
extraneous acoustic signals that may be detected by the transducers, and
must be careful not to confuse them with signals due to flaw growth. Some
background noise may be eliminated by using low frequency filters, but
elimination of other noise may require more complicated methods. A high
level of skill is required to properly plan an acoustic emission inspection
program. Equipment costs vary from moderate ($10,000) to very expensive,
depending on whether a single- or multiple-pickup system is required for the
particular application,
5.2 Acoustic Impact Method
Description of Method
Acoustic impact is the oldest and simplest form of acoustic inspection.
In this method, audible stress waves are set up in a test object by mechanical
39
impact; the frequency and damping characteristics of the vibrations can be
used to infer the integrity of the test object [3], In its most unsophisticated
form, the test object is struck with a hammer, and the operator listens to
the "ringing" caused by the resonant vibration of the object. In a more
sophisticated form, a transducer is attached to the test object, and an
amplifier and display unit are used to produce a visual display of the
frequency and damping characteristics of the "ringing." By comparing the
output with a standard representing acceptable quality, a decision is made
regarding the integrity of the object.
Applications
This method can be used to detect hollow zones and delaminations in
concrete and masonry structures, or it may be used to find studs behind
wall-board. It also has been used to detect delaminations in laminar and
composite materials.
Advantages
The equipment required to carry out the test is relatively inexpensive, and
the test can be done easily.
Limitations
Because the "ringing" can be affected by the mass and geometry of the test
object, an experienced operator may be needed to correctly interpret the
results.
40
5.3 Air Flow
5.3.1 Pltot Traverse
Principle and Applications
Air velocity at a point in an air duct can be determined by a simple method
using a pitot tube in conjunction with a suitable manometer. The velocity in
a duct is seldom uniform across any section, thus a traverse is usually made
to determine average velocity since a pitot tube reading indicates velocity
at only one location. In general, air velocity is greatest near the center
and lowest near the edges or corners. The ASHRAE Handbook indicates that
in round ducts, at least 20 readings should be taken along two diameters of
equal areas. In rectangular ducts, take readings in the center of equal
areas across the cross section of the duct. The number of spaces should be
at least 16, and need not exceed 64 [4]. To determine average velocity in
the duct from the readings obtained, average the calculated individual
velocities or the square roots of the velocity heads.
If there is a disturbance in the air flow in the duct, the pitot tube
should be located at least 7.5 diameters downstream from the disturbance.
The type of manometer used with a pitot tube depends upon the velocity
pressure being measured and the desired accuracy. A draft gage of appropriate
range is usually satisfactory for velocities greater than 1500 fpm. For low
air velocities, a precision manometer is essential. There are many forms of
pitot tubes that have been used to make air velocity measurements.
41
5.4 Air Infiltration Measurements
Principle and Applications
Air leakage is the uncontrolled entry of outdoor air into a building.
Air leakage tests are performed to determine the tightness of buildings and
to determine whether overall building ventilation is adequate. With regard
to building tightness, air leakage tests provide data to determine primarily
the natural air leakage rates occurring in the building under various climatic
conditions and use patterns, tightness of the building compared with other
buildings and with itself after corrective measures have been completed,
location of leakage paths in the building, and the magnitude of each leakage
path.
Measurements of both building air leakage and air exchange rate can be made
using tracer gases. The rate of decay of concentrations of these gases which
are introduced in the air in buildings is the technique used. Another way
to measure building envelope tightness is the fan pressurization technique.
5.4.1 Tracer-Gas Decay Method
The tracer-gas decay method is very versatile and is reported to be the
simplest of the tracer-gas measurement systems [5]. It can be used for both
short and long term measurements. The air measuring equipment may be located
on site or the air samples may be collected into air bags and analyzed off
site. Injection of the tracer gas and measurements of the concentrations
can be made manually or automatically to study the dependence of air exchange
rates as weather changes over time.
A single injection of tracer gas is sufficient for each measurement and
complicated apparatus is not required to control the concentration or
42
automatically inject gas, although several automated techniques have been
developed. As much time as necessary may be allowed for mixing of the tracer
gas with the air. A fan may be used initially to mix thoroughly the tracer
gas with the air, or the fan may be run throughout the entire measurement
procedure. It is convenient to inject tracer gas into the air handling system
for the building. In this case, air is sampled at the return air ducts. If
the building is large or divided into many rooms and does not have a mechanical
air handling system, it may be difficult to obtain a uniform concentration of
tracer gas throughout the building. It is possible that even if a uniform
distribution of tracer gas exists initially, concentrations may decay at
different rates at different locations in the building. The measurements
will reveal the extent of the nonuniformities such as differences in
ventilation rates and localized air leakage.
5,4.2 Fan Pressurization Technique
A building may be pressurized by a fan and the air flow rate measured to
estimate building envelope tightness. At a fixed pressure difference, the
lower the air flow rate, the tighter the envelope. In order to obtain
measureable air flow rates, large pressure differences are usually introduced
in order to overcome any natural pressure differences. For even medium size
buildings this may require the use of a very large fan or simultaneous use
of a number of fans. Measurement of isolated wall and roof areas may avoid
the necessity for using large fans. This stepwise method also provides infor-
mation about permeability of individual building envelope components.
Buildings can be compared directly by expressing the induced air leakage at
a standardized pressure difference, usually 50 Pa [5].
43
The fan pressurization method has the advantage of simplicity, direct
comparability with other buildings and times of measurement, intrinsic
meaningfulness without reference to temperature and wind conditions, usefulness
in locating leakage openings when used in conjunction with infrared thermography,
and the ability to assess the effectiveness of retrofit measures applied one
at a time.
5.4.3 Acoustic Method
Principle and Applications
This method is based on the principle that sound and air readily pass
through openings in buildings. The method is simple, low cost, and can be
used with minimum of training. Small openings through building structures
serve as paths for both air infiltration and sound. Even very small openings
in walls can significantly increase acoustic transmission compared to the
case where the openings are sealed. A sound source is placed on one side of
a wall and probing is carried out on the other side seeking local increases
in sound levels. Almost any sound source of sufficient loudness can be
used; however, preferred sources are steady and broad-band noise containing
many frequencies and a saw-tooth warble tone that sweeps in frequency from
50 to 8000 Hz about three times per second. The broad band sound could be
produced by a vacuum cleaner. Both sounds could be produced using a cassette
tape and portable tape recorder. The warble tone works better because it
is easily discernable. If the sound source is placed outside the building,
the steady and broad-band sound is preferred because it is less annoying.
Sound can be detected near the surface and over a small area using a
mechanic's stethoscope, airline plastic headset, Type I and Type II sound
44
level meters, and low-cost sound meters consisting of a battery-powered
microphone and headphones.
Limitations
Lightweight walls (barriers) will only reduce sound levels slightly
making it difficult to detect leaks from normal sound transmission. Insula-
tion in walls may greatly reduce the sound transmission, especially through an
air passage that is not straight through, thus making it difficult to detect
the leak. Noisy environments can also cause problems in the application of
this method.
5.4.4 Smoke Tracer
Ptinciple and Applications
Some of the commercial smoke tracer systems include guns, pencils, and
sticks. These systems provide a controlled smoke source so that at leakage
sites a thin stream of smoke may be observed. Pressurizing the interior and
thereby causing the smoke to flow outward through any openings is the preferred
method. The controlled smoke source should be located close to the suspected
leakage site.
Limitations
Knowledge of suspected leakage sites is necessary in order to limit leak
detection efforts. This will enable the controlled smoke source to be located
near the leak site. The smoke must be used sparingly because of annoyance
to building occupants and possible material damage. This is a locally used
technique and therefore no extensive use of smoke is recommended in the
building interior,
45
5.5 Air Permeability
Research results suggest that the measurement of the air permeability of
concrete is effective in forecasting the carbonation rate and compressive
strength of site concrete.
Description of Method
This test method provides an estimate of air permeability of concrete in
situ. The test method involves boring a small diameter hole about 2 in.
(50 mm) in depth in the concrete. The hole is plugged and sealed at the
surface of the concrete. A hypodermic needle is pushed through the plug and
a vacuum pressure is applied to the needle. The time for the pressure to
increase to a predetermined level is taken as a measure of permeability.
Research has concluded that the air permeability test is an effective tool
for evaluating the durability and carbonation rate of aged concrete and for
forecasting the compressive strength of site concrete [6].
Limitations
The feasibility of using the air permeability methods for inspecting
concrete has not been demonstrated. Further development work is required if
the air permeability method is to become a reliable NDE method to evaluate
the quality of concrete.
5.6 Break- Off Method
The break-off test is used to determine concrete strength at the site.
Description of Method
A circular slit about 2 in. (50 mm) in diameter and 3 in. (75 mm) in
depth is formed in the concrete either by placing plastic cylinder forms in
46
fresh concrete and removing them after curing, or by drilling into hardened
concrete [7,8]. A transverse force is applied, using a hydraulic testing
device, to the top portion of the concrete cylinder to fracture the resulting
core in the concrete. Fracture or break-off of the core generally occurs
along the embedded end (depth) of the circular slit in the concrete due to
the transverse force. The measured transverse force can be correlated with
the compressive strength by using calibration charts.
Advantages
This in situ test has proven to be a suitable method for in-situ monitoring
the quality of concrete. It has been accepted world-wide and has been approved
as a test method in a number of national codes and standards including those
in Norway and Sweden [7]. The test is a simple, economical, and practical
means to determine concrete strength at the site. Further tests can be
conducted immediately if the results suggest this to be necessary.
Limitations
The concrete needs to be repaired at locations where the cores were broken
off from the concrete.
5.7 Cast-in-Place Pullout
The pullout test measures the force required to pull out a steel insert,
with an enlarged end, which has been cast in the concrete. A pull-out
device may also be inserted into a hole drilled in hardened concrete. The
concrete is subjected to complex stresses by the pullout force, and a cone
of concrete is removed at failure. The pullout forces are usually related
to the compressive strength of the concrete, with the ratio of pullout
47
strength (force divided by surface area of the conic frustum) to compressive
strength being in the range of 0.1 to 0.3. Correlation graphs are used to
relate pullout force to compressive strength. There are several commercially
available test apparatuses for measuring the pullout resistance of concrete.
Description of Method
ASTM has issued a standard test method, C 900, which describes in detail
the pullout assembly and gives allowable dimensions [9]. The pullout insert
is cast in place during the placing of fresh concrete. As noted, a pull-out
device may also be inserted into a hole drilled in hardened concrete. The
insert is either pulled completely out of the concrete, or pulled until
maximum load is reached, with a manually operated hollow tension ram exerting
pressure through a steel reaction ring. Testing and calculation procedures
are also given in ASTM C 900. Techniques have been developed so that the
inserts can be embedded deep in concrete, thereby permitting testing of the
interior concrete.
Because the pullout insert is usually cast in place during placing of the
fresh concrete, these tests must be planned in advance. Alternatively, hardened
concrete can be drilled to receive the pullout insert. This necessitates
drilling through the bottom or backside of a concrete slab, for example, to
the proper depth and width to permit the insertion of the enlarged head. A
smaller hole, permitting insertion of the steel shaft, is drilled through the
remaining portion of the concrete slab. The insert is placed through the
bottom or backside, and the test is performed.
48
Reliability of Method
Malhotra [10] and Richards [11] have shovm that the pullout method can
reliably estimate the compressive strength of concrete. Malhotra [10] found
that the coefficients of variation for pullout test results were in the same
range as obtained from testing standard cylinders in compression. Correlation
coefficients of 0.97 to 0.99 have been obtained for normal weight concrete
from curve fitting of pullout and compression test results.
Advantages and Disadvantages
The pullout technique is a nondestructive test method which directly
measures a strength property of concrete in place. The measured strength is
generally thought to be a combination of tensile and shear strengths. The
major disadvantage of the pullout test is that a cone of concrete is sometimes
pulled out, necessitating minor repairs. However, if the pullout force is
quickly released just when failure begins, the concrete cone will not be torn
loose, and no repairs will be required. Another disadvantage is the need to
plan where inserts are to be located and to make provisions for them before
placing concrete. The feasibility of drilling holes into hardened concrete
and of inserting pullout devices was explored [12]. This would eliminate the
need to install the inserts prior to placing concrete.
5.8 Electrical Potential Measurements
Information on the corrosion state of metals can be obtained from
measuring the electrical potential difference of the metal using a standard
reference electrode and a voltmeter. If the metal has a certain difference
in electrical potential, active corrosion is very likely.
49
Measurements on Steel in Concrete
The electrical potential method is commonly used to assess the corrosion
condition of steel reinforcement in concrete. The electrical potential
differences of steel reinforcement are measured by making an electrical
connection from a voltmeter to the reinforcement, and a second electrical
connection from the voltmeter to a reference cell in physical contact with
the surface of the concrete. Dry concrete must be moistened before
electrical measurements are made. A saturated copper-copper sulfate electrode
is commonly used as the reference cell. The electrical potential difference
of the reinforcement below the location of the reference cell is measured.
If the electrical potential difference of the steel reinforcement is
more negative than -0.35 volts versus the copper sulfate electrode, active
corrosion is probably taking place. Values in the range of -0.30 to -0.35
volts seem to suggest that corrosive conditions are developing within the
concrete, while values less negative than -0.30 volts indicate that the
steel is probably passive — i.e., not corroding [13].
An electrical potential difference diagram of a concrete slab can be
constructed in which areas of similar potential differences are outlined.
This diagram can be used to identify areas where the reinforcement may be
corroding.
Advantages
The equipment is inexpensive, and only a moderate amount of skill is
needed to make the measurements. Measurements of the electrical potential
differences of steel reinforcement provide information concerning the
probability of corrosion.
50
Limitations
Information on either the rate or the extent of corrosion is not
obtained. In addition, a direct electrical connection must be made to the
reinforcing steel. If the steel is not exposed, then some concrete covering
must be removed.
5.9 Electromagnetic Methods
The presence of flaws or changes in composition of metals will affect
their electrical and magnetic properties. Therefore, it is possible to infer
the presence of anomalies by making measurements which rely on the electrical
and magnetic properties of metals. The following NDE methods can be used:
eddy current testing, magneto-inductive testing, and magnetic particle testing.
Also, a method has been proposed for in situ measurement of steel fiber content
of steel fiber reinforced concrete.
5.9.1 Eddy Current Inspection
Eddy current inspection is a versatile NDE method based on the principles
of electromagnetic induction; it is applicable to inspection of metals [2] and
to the measurement of the thickness of nonconductive coatings on a conductive
metal [14].
Description of Method
A coil carrying an alternating electric current will have an associated
alternating magnetic field which acts to oppose the flow of current into the
coil. When the coil is brought near a conductive material, the alternating
magnetic field will induce in the material a closed loop current flow known
as eddy current. The eddy currents will also be alternating, and, therefore,
51
a secondary magnetic field is associated with them. The secondary magnetic
field will oppose the magnetic field of the coil. When the energized coil
is brought near a metal surface, there will be a change in the current flow
in the coil. Measuring the changes in the current flow (or the coil impedance)
is the basis of eddy current inspection.
The magnitude of the changes in the coil current will depend on the
intensity of the eddy currents induced in the metal. Factors which influence
the intensity of eddy current flow include:
1
.
the frequency and magnitude of the coil current2. the electrical conductivity of the metal3. the magnetic permeability of the metal4. the size and shape of the test object5. the proximity of the coil to the test object6. the presence of discontinuities or inhomogeneities in the metal [15].
The electrical and magnetic properties of the metal are controlled by
alloy composition, microstructure, and residual stress [2].
Eddy Current Inspection Systems
The principal elements of an eddy current inspection system include the
inspection coil, and oscillator to provide coil excitation, a detector to
monitor changes in coil impedance, and an output device to display the test
results. Various coil geometries are available, depending on the specific
application. An important principle when inspecting for discontinuities is
that the maximum signal is obtained when the eddy current flow is transverse
to the flaw. Thus, the user needs to understand the relationships between
coil configuration, eddy current flow and type of flaw to be detected.
The frequency of the excitation current affects the depth of the eddy
currents and the sensitivity of flaw detection. The coil frequency can be
increased to detect small, near-surface flaws; penetration is reduced, but
52
sensitivity is increased. If sub-surface flaws are to be detected, a lower
frequency should be used; however, the minimum size of flaws that can be
detected is increased. Thus, there is a trade-off between penetrating ability
and sensitivity; this is also common to other inspection methods. The range
of frequencies is from 200 Hz to 6 MHz, with the lower frequencies used
primarily for inspecting ferromagnetic metals [2],
The detector circuit can also take many forms, depending on the application
of the instrument. In any case, the changes in coil impedance that occur
during inspection are small; bridge circuitry, similar to that used to monitor
electrical resistance strain gages, is used to detect these changes. In
making a measurement, the impedance bridge is first balanced by using an
internal adjustment or placing the coil on a reference object of acceptable
quality; then the coil is placed on the test object. Any difference between
test object and reference object will result in an imbalance of the bridge
which is indicated on the output device. There are many output devices;
audible alarms, meters, X-Y plotters, strip-chart recorders, magnetic tape,
storage oscilloscopes, and computers.
Instrument Calibration
Because many factors may affect the coil impedance when a test is
performed, the object used to calibrate the instrument must be carefully
chosen. For example, to detect cracks, the reference object must have the
same electrical and magnetic properties as the test object; otherwise,
differences in alloy composition could be interpreted as a crack. Therefore,
a user must be knowledgeable about operating an eddy current device in order
to calibrate it properly and to interpret test results.
53
Applications
Eddy current inspection has many uses, including the detection of flaws
such as cracks, porosity, or inclusions in metals; detection of changes in
alloy composition or microstructure; and the measurement of the thickness of
nonconductive coatings on a metal.
Limitations
One important limitation of eddy current inspection is the volume of
material examined. The inspection depth depends on the penetration depth of
eddy currents, the intensity of which decreases exponentially with depth.
The strength of the signal due to a particular defect will depend on the
nearness of the coil to the surface of the test object. As this distance
called "lift-off" increases, the signal strength diminishes. The "lift-off"
effect is so strong that it may mask signal changes due to defects.
Therefore, care must be taken to ensure uniform contact between coil and
test object; it may be difficult to test objects with rough or irregular
surfaces. The "lift-off" effect may be used to measure the thickness of
nonconductive coatings on conductive metals, or non-magnetic metal coatings
on magnetic metals. Proper calibration samples are required in order to use
an eddy current instrument as a thickness gage.
5.9.2 Magneto- Inductive Methods (Magnetic Field Testing)
This technique is only applicable to ferromagnetic metals and is primarily
used to distinguish between steels of different alloy composition and
different heat treatments. The principle involved is electromagnetic induction.
The equipment circuitry resembles a simple transformer in which the test object
acts as the core [2], There is a primary coil connected to a power supply
54
delivering a low frequency (10 to 50 Hz) alternating current, and a secondary
coil feeding into an amplifier circuit. In the absence of a test object, the
primary coil induces a small voltage in the secondary coil, but when a
ferromagnetic object is introduced, a much higher secondary voltage is induced,
The nature of the induced signal in the secondary coil is a function of the
magnetization characteristics of the object. Changes in these characteristics
are used to distinguish between samples of different properties. As in the
case of eddy current inspection, this method can only be used for quantitative
measurement if proper calibration is performed.
5.9.3 Cover Meters
Cover meters are portable, battery-operated magnetic devices that are
primarily used to estimate the depth that reinforcing steel (bars and tendons)
is embedded in concrete, and to locate its position. In addition, some
information can be obtained regarding the dimensions of the reinforcement [10],
Principle and Applications
Cover meters are based on the magneto-inductive principle. A magnetic
field is induced between the two faces of the probe (which houses a magnetic
core) by an alternating current passing through a coil. If the magnetic
field passes through concrete containing reinforcement , the induced secondary
current is controlled by the reinforcement. The magnitude of this change in
inductance is measured by a meter. For a given probe, the magnitude of the
Induced current is largely controlled by the distance between the steel
reinforcement and the probe.
The relationship between the induced current and the distance from probe
to the reinforcement is nonlinear, largely because the magnetic flux intensity
55
of a magnetic material decreases with the square of the distance. In addition,
the magnetic permeability of the concrete, even though it is low, will have
some effect on the reading. Therefore, the calibrated scales on the meters
of commercial equipment are nonlinear. Also, a meter must be readjusted
if a different probe is attached.
The probe is highly directional — i.e., sharp maximum in induced current
is observed when the long axis of the probe and reinforcement are aligned,
and when the probe is directly above the reinforcement.
Some commercial cover meters can measure concrete cover over reinforcement
up to 8 in, (200 mm). By using spacers of known thickness, the size of
reinforcing between 3/8 and 2 in. (10 to 50 mm) can be estimated.
Another possible application of the cover meter is to estimate the
thickness of slabs which are accessible from both sides. If a steel plate is
aligned on one side with the probe on the other side, the measured induced
current will indicate the thickness of the slab. For this application, a
series of calibration tests must be performed first, British Standard
BS 4A08 gives guidance for the use of cover meters.
Advantages
Cover meters are portable, inexpensive instruments that can be easily
used. They are useful when reinforced concrete has only one layer of
widely separated reinforcing bars.
Limitations
In highly reinforced concrete, the presence of secondary reinforcement
makes it difficult to determine satisfactorily the depth of concrete cover.
Furthermore, reinforcing bars running parallel to that being measured
56
influence the induced current if the distance between bars is less than two
or three times the cover distance [10].
5.9.4 Magnetic Particle Inspection
Principle of Method
This inspection method relies on the tendency of cracks to alter the
flow of a magnetic field within a metal so that fine magnetic powder will be
attracted to the crack zone, allowing cracks to be Identified [2,16,17], For
example, consider a bar magnet in which the magnetic field flows through the
magnet from south to north poles. If ferromagnetic particles are sprinkled
over the middle surface of a crack-free magnet, there will be no attraction
because the magnetic field lies wholly within the magnet. Now consider a
cracked magnet; the two sides of the crack acts as north and south poles,
and the magnetic field bridges the gap. However, some of the magnetic field
will leak out of the magnet into the air, and ferromagnetic powder would be
attracted by the leakage field. Therefore, the attraction of the powder
indicates a crack. A subsurface crack would also produce a leakage field,
but the response would be weaker than for a surface crack.
Application of Method
In using the magnet particle method, it is necessary to magnetize the
object being inspected, apply ferromagnetic particles, and then inspect for
cracks. Two general types of magnetic fields may be induced in the test
object: circular and longitudinal. A circular field is produced by passing
an electric current through the test object: the magnetic field then would
be concentric with the direction of current flow. A longitudinal field
could be created by placing the test object inside a coil carrying electric
57
current: the magnetic field then would be parallel to the longitudinal axis
of the coil. The direction of the magnetic field relative to the test object
controls which cracks will be detected. Strong leakage fields are produced
by cracks which intersect the magnetic lines of force at an angle; no leakage
fields are produced by cracks parallel to the magnetic lines of force.
Therefore, complete inspection should include rotation of the test object
with respect to the magnetic field to make sure that all existing cracks
intersect the magnetic field lines.
In field inspections, it usually is not practical to pass a current
through the entire part or surround the part with a coil. Portable units are
available that permit inspection of small portions of the test object at a
time. For example, prods can introduce a flow of current between two contact
points on the object. In this case, a circular magnetic field is Induced. A
yoke — a U-shaped electromagnet in which the poles are brought into contact
with the test object — can also be used. With a yoke, a longitudinal magnetic
field is set up in the object, and the lines of force in the electromagnet
run from one pole to the other. With either portable method, only a small
portion of a large test object can be inspected at one time; 12 in. (300 mm)
is a practical limit for spacing between prod contacts [2].
The choice of current used to magnetize the test object is important.
If subsurface cracks are to be detected, direct current should be used because
alternating current will only produce a magnetic field near the surface.
The direct current may be from a constant or pulsating source, though the
pulsating type is preferred because it imparts greater mobility to the
ferromagnetic powder. The current supply is low voltage and very high amperage
for user safety, but still permits strong magnetization of the test object.
58
Inspection is usually carried out with the current on, but if the metal has
high retentivity (permanent magnetism), the current may be turned off before
the powder is applied.
The powder used to indicate the leakage fields may be dry or suspended
in a liquid. Dry powders are preferred for the best sensitivity to subsurface
cracks and should be used with direct current. Wet powders are superior for
detecting very fine surface cracks. To improve visibility, powders are
available in various colors, providing high contrast with the background. In
addition, fluorescent particles are available for increased visibility.
Advantages
The magnetic particle inspection method has several advantages over
other crack detection systems [2]. Portable equipment is available that can
be readily taken to the inspection site. This equipment is inexpensive
and simple to operate; positive crack indications are produced directly on
the part and no electronic equipment is needed. Any part that is accessible
can be Inspected.
Limitations
This method will only work with ferromagnetic metals. For complete
inspection, each area needs to be inspected more than once using different
magnetic field directions; very large currents are needed to inspect large
areas at once. Experience and skill are needed to interpret properly the
particle indications and to recognize patterns which do not indicate cracks.
Demagnetization may be required after inspecting steels with high magnetic
retentivity. The maximum depth of the flaw detection is about 0.5 in. (13 mm),
and the detectable flaw size increases as flaw depth increases.
59
Portable equipment is limited with regard to the current available for
the inspection. For detection of deep lying discontinuities and for coverage
of large areas with one prod contact, a larger machine, such as a mobile
unit or stationary unit with higher-amperage output is required.
5.9.5 Steel Fiber Content
Description of Method
The electromagnetic apparatus for measuring steel fiber content of steel
fiber reinforced concrete consists of a measuring device and several
attachments having circular or square openings in the center into which the
test specimens are inserted [18]. In the attachments there are coils for both
excitation and induction of an electric current. With an increase in steel
fiber content of the specimen in the attachment, the induced electric current
increases. Based on this principle, the steel fiber content can be determined
from a reading of the induced current. This method can be used for both
hardened and fresh concrete. For fresh fiber reinforced concrete, it must
be placed in molds that do not contribute to the induced electric current.
Limitations
This electromagnetic method for in situ measurement of steel fiber
content in hardened and fresh concrete shows promise as a research tool.
The method has not been used extensively in the field. Further development
work is required it if is to become a reliable NDE method.
5.10 Holography
Description of Method
Two methods available for nondestructive inspection are optical holography,
using visible light waves, and acoustical holography, using ultrasonic waves.
60
In these methods, a two step process creates a three-dimensional image of a
diffusely reflecting object [14], The first step involves recording both the
amplitude and phase of any type of coherent wave motion emanating from the object,
The recording of this information in a suitable medium is called a hologram.
At a later time, the wave motion can be reconstructed from the hologram to
regenerate a three-dimensional image having the shape of the object. The
nondestructive inspection of an object is accomplished by using the regenerated
three-dimensional image as a template against which any deviations in the
shape or dimensions of the object can be observed and measured [14],
Limitations
Skill is required in developing holograms (three-dimensional images) and in
the interpretation of comparing holograms in order to measure deviations that
have occurred in the shape or dimensions of the object that is inspected.
5.11 Leak Testing Method
Principle of Method
Leakage testing is the detection and sizing of holes in pipes and tanks
which permit the escape of liquids or gases [19]. There are many different
methods of leak testing, but they can be generally classified into two
categories. In the first, the leaking system is monitored under normal
operating conditions. This includes the use of pressure meters, the applica-
tion of a soap solution, or the use of audio or amplified listening devices.
In the second category, a particular substance is added into the system flow
to provide special indications of leakage. This includes additives such as
colored dyes, Freon 12 and helium gas, radioactive tracers, and odorous
indicators.
61
Applications
Many leak detection methods are suitable for fi«ld application. Liquid
storage vessels and above ground piping can usually be checked visually for
leakage under normal operating conditions with no special equipment. Gas-
carrying systems usually can be checked best in the field with a soap solution
or (with freon gas added to the system) a propane torch. These systems have
no special power requirements, and none of the equipment involved weighs
more than 5 lb (2 kg).
Advantages
Leak detection methods can locate flaws too small to be found by any
other NDE technique. Leaks with rates as small 10"^^ cc/sec can be detected
with radioactive tracers and radiation monitoring devices, while a soapy
water solution can locate leaks with rates as low as 10"^ cc/sec [19].
Limitations
Flaws can be detected only if they penetrate through a structure that
can be held at pressure conditions exceeding those of the surrounding
atmosphere.
5.12 Longitudinal Stress Waves
Description of Method
The speed that longitudinal (parallel to the grain) stress waves travel
in wood has been measured by resonant frequency, impact, and by ultrasonic
stress-wave devices [20]. Stress wave-speed (speed of sound) of waves that
travel in the longitudinal direction is affected by several factors such as
moisture content, temperature, knots, specific gravity, and orientation of
62
grain in the wood (grain angle). The type of longitudinal stress wave induced
in wood does not have a significant effect on stress wave-speed. Stress
waves show promise for rapid lumber grading and predicting mechanical
properties of wood [20].
Development of an effective in situ test method to evaluate the soundness
of wood subject to deterioration would be useful in appraising its service
life. Wood members under some environmental exposures may lose some structural
integrity through decay or chemical degradation. Stress-wave transmission
has been investigated to determine nondestructively the extent and location
of degradation in wood [21].
Limitations
Additional research is needed to demonstrate the feasibility of using
longitudinal stress waves to assess the mechanical properties of wood and for
rapidly determining the quality of wood members.
5.13 Maturity Concept
Principle and Application of Method
The maturity concept has been proposed as a method for predicting early
age strength development of hardening concrete. It relates the combined
effect of temperature and hydration time of concrete to its strength [22].
Maturity (M) is usually expressed as:
M = Z (T-To)At
where T = temperature of the concrete
Tq = the highest temperature below which the strength ofhardening concrete does not change
At = the increment of time for each temperature.
63
According to the maturity concept, the strength of a given concrete mix is a
single-valued function of maturity, independent of the actual temperature
history [22]
.
To apply this method, one first experimentally determines the strength-
maturity relation of the concrete mix to be used in building the structure.
This is done by making and curing standard specimens in a laboratory, monitor-
ing the actual concrete temperature, and testing strength at various ages.
From the temperature record, the corresponding maturity value at each test age
is calculated, and strength versus maturity data are generated. Various
equations for the strength-maturity relation have been proposed, and can be
used in analysis of the data [23~25]. During construction, the in-place
concrete temperature is recorded, from which maturity values at any age can
be determined. The previously determined strength-maturity calibration
curve is used to predict the strength of the in-place concrete. The maturity
method is identified in ACI Committee Report 306R-78 as a viable means of
predicting the in situ strength of concrete [26].
Maturity can be calculated using temperature records from continuous
strip-chart recorders or from digital data-loggers, which print out the
temperature at regular time intervals. As an alternative, commercial
"maturity meters" are available; these monitor the in-place temperature and
automatically compute the cumulative maturity. Such instruments cost about
$3000. Multi-channel maturity meters have been developed to allow monitoring
maturity at many locations with a single instrument. In addition, single-use,
disposable meters have been produced, although their reliability has not
been tested. Finally, one may use programmable data-loggers as maturity
meters.
64
Advantages
Because In-place temperatures are measured, the maturity method accounts
for one of the major factors affecting early-age strength development of
concrete.
Limitations
Since only temperature and time are measured, another method is needed
to verify that the in-place concrete has the correct mix proportions. Other-
wise, the user has no way of knowing if the strength-maturity calibration
curve is appropriate. Accelerated curing tests of samples taken from the
concrete batch, or other in-place tests discussed in this report may be
used. Because of the nonuniform temperature distribution in the structure,
the temperature probes must be carefully located to avoid overestimating
maturity development in the critical strength regions. In addition, there
is a question about whether the equation given earlier in this Section (5.13)
is the best temperature-time function for computing maturity. Carino discussed
this problem and suggested alternative methods [25]. Finally, the maturity
method is only applicable for strength prediction in new construction and
cannot be used to estimate the strength of concrete in existing structures.
5.14 Microwave Inspection
Microwaves (or radar waves) are a form of electromagnetic radiation
which have frequencies between 300 MHz and 300 GHz corresponding to wave-
lengths of 1 m to 1 mm. Microwaves are generated in special vacuum tubes
called klystrons and transported in a curcuit by waveguides. Diodes are
commonly used to detect microwaves.
65
Applications
Because of their electromagnetic nature, microwaves can be reflected,
diffracted, and absorbed. These waves are absorbed by water and this has led
to development of a method for determining the moisture content of concrete.
The use of microwaves to estimate the moisture contents of concrete and
roofing materials has been explored [10,27,28], Similar to capacitance
instruments (see Section 5,16,2), changes in the dielectric properties of
materials are detected. Since moisture affects the dielectric properties of a
material, changes in moisture content in the material can be detected. Boot
and Watson report that the microwave technique only estimates the moisture
content of concrete within 12 to 30 percent of its mean value [29], The low
accuracy of micowave inspection is largely attributed to the heterogeneity of
concrete, and the internal scattering and diffraction it causes.
Limitations
The feasibility of using microwaves for inspecting installed construction
materials has not been demonstrated. Further development work is required if
the microwave method is to become a reliable field NDE method.
5,15 Middle Ordinate Method
Description of Method
In this method a laboratory instrument is used that is capable of
detecting stiffness variations within boards (lumber) over lengthwise regions
of less than two feet [30], A bending moment is applied to each end of the
board under test. Stiffness calculations are based upon the assumption that
short segments of a board undergoing bending approximate arcs of circles with
varying radii. The middle ordinate instrument measures, either on a continous
66
basis or in discrete steps, the perpendicular distance between the midpoint
of a chord and its arc. This distance or deflection is inversely related to
stiffness. The instrument provides a means of assessing in the laboratory
the strength-reducing potential of defects in lumber.
Limitations
This research method has not been used in the field. Additional research
and field use are needed to demonstrate the feasibility of using the middle
ordinate method as a reliable NDE method to inspect lumber at the job site.
5.16 Moisture Detection Methods
Many of the problems encountered in a building are caused by moisture.
Visual inspection can reveal obvious surface moisture, but even if a surface
is dry, subsurface moisture can be present. Four NDE methods are often used
for moisture inspection measurements. The types of instruments or methods
used include electrical resistance probes, capacitance instruments, nuclear
meters, and infrared thermography [27,28,31].
5.16.1 Electrical Resistance Probe
Principle and Applications
The resistance probe method involves measuring the electrical resistance
of a material, which decreases as the moisture content increases. Most
instruments consist of two closely spaced probes and a meter-battery assembly
which are enclosed in one housing or in two attached assemblies. The probes
are usually insulated except at the tips so that the region being measured
lies between the tips of the probes. The probe can penetrate soft materials,
such as roofing membranes, so that moisture at various distances below the
67
surface can be detected. Operation of a resistance probe is very simple. A
voltage is impressed between the probes and the resistance measured.
Probe instruments have been used for moisture detection in plaster,
brick, concrete, and roofing materials. Similar procedures have been used for
determining the electrical resistance of soils, except a four probe system is
used.
Calibration
The electrical resistance probe and other moisture measuring instruments
are usually calibrated by obtaining relationships between their response and
the moisture content of materials similar to those being inspected. The
moisture contents of the reference specimens are gravlmetrlcally determined
— l,e., specimens are weighed before and after oven drying with the differences
in weight considered to be their moisture contents.
Advantages
The simple, inexpensive Instruments, while giving only an approximation
of the extent of wetness, are useful in identifying wet areas and for
determining moisture migration patterns. More sophisticated instruments
appear to be capable of giving semi-quantitative information if they are
properly calibrated.
Limitations
Electrical resistance probe instruments do not determine moisture
contents precisely. When used on roofing membranes the test method is
considered to be destructive.
68
5.16.2 Capacitance Instruments
Principle and Applications
Capacitance instruments used to detect moisture are based on the
principle that moisture can affect the dielectric properties of a material [31]
The dielectric constant, K, of a material is a relative measure of the ability
of a material to store electrical energy and is given by:
K = C/Co
where C is the capacitance of a material and Cq is the capacitance of a
vacuum
.
The dielectric constants for many dry building materials are usually
low; e.g., for dry roofing materials, K ranges from 1 to 5, while water has
a K of approximately 80 [28]. The value of K for a moist material will
theoretically increase linearly as the volume fraction of water increases.
Capacitance-radio frequency instruments have been used to measure the moisture
contents of paper products, wallboard, and roofing materials. Commercial
capacitance Instruments have various electrode configurations. The electrodes
are attached to a constant frequency alternating current source and establish
an electrical field in the material to be tested. Current flow or power
loss — indicating moisture content — Is then measured. Most Instruments
operate in the radio frequency region (1 to 30 MHz).
Advantages
Capacitance instruments are portable and measurements can be taken
rapidly.
69
Limitations
Capacitance meters have extreme sensitivity to surface moisture; because
of this it is essential that the roof surface be dry when capacitance surveys
are made [32]. An investigation by Knab et al. suggests that capacitance
Instruments may not give reliable quantitative measurements of the moisture
contents of roofing systems beyond the "threshold" moisture content [31].
5.16.3 Nuclear Meter
Principle of Method
Fast neutrons, emitted during the decay of radioactive isotopes, are
used in making moisture content measurements [28,29]. Fast neutrons from the
isotope source enter the material and are both scattered and slowed by
collisions with the nuclei of the atoms composing the material. Nuclei of
all materials slow down the neutrons by momentum exchange, but the speed
reduction is greatest for collisions with hydrogen nuclei, which have about
the same mass as the neutrons. Some of the slow or thermal neutrons are
scattered so that they reach the slow neutron detector in the instrument
and are counted for a specific period of time. The thermal neutrons reaching
the detector are much more likely to have collided with hydrogen nuclei than
with other atomic nuclei because the scattering cross-section of hydrogen is
greater than for other atoms likely to be present. The detector measures
primarily the backscattering of slow neutrons which have collided with hydrogen
nuclei in the surface region of materials. For example, the depth of
measurement is limited to 2 to 8 in. (51 to 203 mm) in soils.
70
Commercial Meters and Applications
Nuclear meters are used to measure both moisture content and density of
soils, portland-cement concrete, asphaltic concrete, and roofing materials
[10,27,28]. These meters consist of a shielded radioactive isotope source,
a detector or counting device, and readout equipment. In commercial meters,
the isotopes used are radium 226-beryllium, and americium 241-beryllium.
Both americium and radium are alpha particle emitters. These particles
interact with the nucleus of beryllium, resulting in the emittance of fast
neutrons.
In addition to neutron sources, most commercial nuclear moisture meters
also have gamma ray sources. The gamma rays are used to determine the density
of materials. See Section 5.25 about Radioactive Methods for an explanation of
the principle.
Advantages
Nuclear meters are portable, and moisture measurements can rapidly be
made on materials.
Limitations
The hydrogen atoms of building materials in addition to those of water
will contribute to the number of detected thermal neutrons. For example,
asphalt in a roofing membrane may contribute to a reading because it contains
bonded hydrogen atoms. For hydrogen-containing materials, the meter must be
calibrated with samples identical to those expected during field inspection.
Also, a license must be obtained from the Nuclear Regulatory Commission to
use the radioactive isotopes in the neutron source of the neutron moisture
meters. Transportation of meters may be difficult because of restrictions.
71
5.16.4 Infrared Thermography
In addition to locating heat loss, infrared thermography can be used to
detect moisture in building materials if heat is flowing through them. The
presence of moisture will affect the heat transfer properties of materials;
this permits the identification of wet areas by thermography. The principles
involved in making thermography scans are discussed under Thermal Inspection
Methods (Section 5.29). The infrared thermography method is being used in
making aerial scans of roofs. Large roof areas and many buildings can be
scanned in a relatively short time [27,28]. Handheld infrared cameras also
are being used to measure heat losses and to detect moisture in roofing
systems [32,33]. Additional applications of infrared thermography are given
in Section 5.29. In using thermography to detect moisture in roof systems,
it is necessary to assume that temperature gradients are caused by moisture
and are not associated with differences in roofing composition or thickness.
Because construction and thickness variations can be present, results from
thermographic inspections should be interpreted carefully.
Limitations
Some destructive testing may be necessary to verify roofing composition
and thickness.
5.17 Nuclear Density Meter
See Section 5.16.3.
72
5.18 Paint Inspection Gages
5.18.1 Tooke Gage
Principles and Applications
The Tooke Gage measures dry paint film thickness by the microscopic
observation of a small v-groove cut into the paint film. In addition, the
number of paint layers and their individual thicknesses can be determined.
The thickness of dry coating applied to any type of surface can be measured
— e.g., to wood, metal, glass, or plastic. The Tooke Gage is easily portable,
with overall dimensions of 4.5 x 3.5 x 1 in. (114 x 89 x 25 mm); and it weighs
26 oz (0.7 kg). Three cutting tips are furnished; these permit measurements
of film thicknesses up to 50 mil (0.13 mm).
Limitations
A disadvantage of this method is that a cut is made in the paint film
which may have to be repaired, depending on the substrate and the severity
of the environment.
5.18.2 Pencil Test
Principle and Applications
This rapid and inexpensive method can be used to determine film hardness
of an organic coating on a substrate using pencil leads of known hardness.
Testing is started with the hardest pencil lead and continued down the scale
of hardness to either of two end points: (1) the pencil that will not cut
into or gouge the film, or (2) the pencil that will not scratch the film.
Advantages
The method causes only slight damage to the coating.
73
5.18.3 Magnetic Thickness Gages
5.18.3.1 Magnetic Pull- Off Gage
Principle and Applications
These instruments measure thickness by using a spring calibrated to
determine the force required to pull a permanent magnet from a ferrous base
coated with a nonmagnetic film. The instrument is placed directly on the
coating surface to take a reading. The attractive force of the magnet to the
substrate varies inversely with the thickness of the applied film. The spring
tension required to overcome the attraction of the magnet to the substrate is
shown on the instrument scale as the distance between the magnet and the
substrate.
5.18.3.2 Magnetic Flux Gage
Principle and Applications
These instruments measure coating thickness by changes in the magnetic
flux within the instrument probe or the instrument itself. The instrument
probe must remain in direct contact with the coating at all times during
measurement. The magnitude of flux changes as an inverse (nonlinear)
function of the distance between the probe and the ferrous substrate. The
testing apparatus is mechanically or electrically operated. The mechanically
operated instruments house an integral horseshoe magnet, the contacts of
which are placed directly on the coated substrate. The electrically operated
gages utilize a separate instrument probe that houses the magnet and the
gages must be placed directly on the coated surface. In both types, the
coating thickness is shown on the instrument scale or meter.
74
The methods for nondestructive measurement of dry film thickness of
nonmagnetic coatings applied to a ferrous base are described in ASTM Standard
D 1186 (Appendix D) . In addition, the method for nondestructive measurement
of film thickness of pipeline coatings on steel is described in ASTM Standard
G 12 (Appendix D) .
5.18.4 Wet Film Thickness
Measurements of wet film thicknesses of organic coatings using the
Interchemical Wet Film Thickness Gage and the Pfung Gage are described in
ASTM Standard D 1212 (Appendix D) . Wet film thickness measurements using
Notch Gages are described in ASTM Standard D 4414 (Appendix D)
.
5.18.4,1 Interchemical Wet Film Thickness Gage
The gage consists of an eccentric center wheel supported by two concentric
wheels so as to provide two scales that are bilaterally symmetrical. The
gage is rolled on the wet film; as it rotates there is a change in clearance
between the wet film and the eccentric wheel. The point at which the film
first touches the eccentric center wheel is a measure of the thickness of the
paint film. The gage is available in a variety of ranges and can measure wet
film thickness up to 60 mils on the English scale and up to 700 yra on the
metric scale.
Limitations
At locations where thickness measurements are made, the coating film may
have to be repaired.
75
5.18.4.2 Pfung Gage
Principle and Applications
The gage consists of a convex lens that is mounted in a short tube that
slides freely in an outer tube. The lower surface of the convex lens has a
radius of curvature of 250 mm. Compression springs keep the convex surface
out of contact with the wet film until pressure is applied to the top of
the short tube forcing the lens down through the film to the substrate.
After the pressure is released, an oversized circular spot is retained on the
lens. The diameter of the circular spot retained on the lens is a measure of
the wet film thickness.
Limitations
At locations where thickness measurements are made, the coating film may
have to be repaired.
5.18.4.3 Notch Gage
Principle and Applications
Square or rectangular, and circular, notch rigid metal gages are used to
measure film thicknesses ranging from 0.5 to 80 mils (13 to 2000 pm) for square
or rectangular gages and from 1 to 100 mils (25 to 2500 ym) for circular gages.
These gages are used on coatings on flat substrates. Notched gage measurements
are neither accurate nor sensitive, but they are useful In determining
approximate wet film thickness of coatings where sizes and shapes of coated
objects prohibit the use of the more precise methods given in ASTM Standard
D 1212. The square or rectangular gages are pushed perpendicular into the
film and the circular gages are rolled perpendicularly across the film.
Thickness is determined from tabs and notches wetted by the film.
76
Limitations
At locations where thickness measurement are made, the coating film may
have to be repaired.
5.19 Pin Hole Dectector
Principle and Applications
This type of device Is used to find pin holes (holidays) In nonconductlve
coatings applied to metals. Pinhole and holiday detectors are of three
general types; low voltage wet sponge, direct current high voltage, and
alternating current electrostatic types [34]. Most low voltage commercial
Instruments consist of a probe or electrode, which makes contact with the
coating through a moist sponge, and an earth lead, such as alligator clip,
which Is attached to an area of bare metal. When the moist sponge passes
over a pin hole, an electrical circuit Is completed and an alarm sounds.
Most high voltage detectors use In general a direct current power source In
the range of 500 to 1500 volts [35]. High voltage detectors basically
function on the same operating principle as the low voltage detectors except
that a sponge Is not used. The alternating current electrostatic type
detector Is used for testing conductive linings applied over steel substrates.
Limitations
There are several problems In using the detectors to Inspect for pin holes,
If a metallic object is completely coated, part of the coating must be removed
so that the earth lead can make contact with the metal. The voltage must be
carefully selected to match the coating thickness because too high a voltage
would break through a thin film even if pin holes were not present. The
77
results are qualitative since no information on the size of a pin hole
is given.
5.20 Point-Load Test
This test is intended to estimate the compressive and tensile strength
of concrete using small cores.
Description of Method
Relatively small cores of plain or fibrous concretes about 2.7 in. (68
mm) in diameter and 4 in. (100 mm) in length are tested using a point load in
a diametral test [36]. Cores have to be drilled and extracted from the concrete
for which strength determinations are to be made. The apparatus for the
point-load test is a portable testing machine consisting of a loading system
and load measuring capability. A truncated steel cone is used to apply
the point load at mid-length of the core along its diameter until failure
occurs. The point-load test is essentially an indirect tensile test and will
give a maximum tensile stress which differs from the actual direct tensile
stress because of high compressive stress under the load. The compressive
strength can be related to the tensile strength through empirical formulae.
Advantages
This test is quick to carry out, is relatively inexpensive, and can be
performed in the field on a simple and easily portable apparatus. A total of
six point-load tests may be expected to provide a realistic estimate of concrete
strength.
78
Limitations
Additional research is needed to demonstrate the reliability of using
the point-load test to assess the strength of concrete and for this test to
become a reliable in situ NDE method. The concrete needs to be repaired where
cores are taken,
5.21 Probe Penetration Method
Principle of Method
The probe penetration method involves measuring the exposed length of a
cylindrical steel probe driven into concrete by a powder charge. This method
is useful for assessing the quality and uniformity of concrete in situ, and
for delineating areas of poor quality or deteriorated concrete in structures.
Probe penetration results have also been used to estimate the compressive
strength of concrete by using correlation graphs. The graphs are constructed
by plotting the exposed lengths of probes versus experimentally measured
compressive strengths. This can be done by performing penetration tests on a
concrete slab and taking core samples for compression testing.
Probe Equipment and Its Use
The Windsor Probe is the most commonly selected, and possibly the only,
commercially available apparatus for measuring the penetration resistance of
concrete. It consists of a special driving gun which uses a 32 caliber blank
with a precise quantity of powder to fire a high-strength steel probe into
the concrete. A series of three measurements is made in each test area.
The length of a probe extending from the surface of the concrete can be
measured with a simple device.
79
Operating procedures for the Windsor Probe are given by the manufacturer.
In addition, testing procedures are given in ASTM Standard C 803 (Appendix D)
.
The probe can be easily operated by concrete inspectors, and is readily
portable.
The manfacturer supplies a set of five calibration curves, each
corresponding to a specific Moh's hardness for the coarse aggregate used in
the concrete. With these curves, probe measurements can be converted to
compressive strength values. However, Ami observed that use of the
manufacturer's calibration curves often resulted in grossly incorrect
estimates of the compressive strength of concretes [37], Therefore, the
Windsor Probe should be calibrated by the individual user, and should be
recalibrated whenever the type of aggregate or mix design is changed.
The Windsor Probe can be used for assessing the quality and uniformity
of concrete because physical differences in a concrete will affect its
resistance to penetration. A probe will penetrate deeper as the density,
subsurface hardness, and strength of the concrete decrease. Areas of poor
concrete can be delineated by making a series of penetration tests at regularly
spaced locations.
The Windsor Probe has been used to estimate the compressive strength of
concrete. However, the relationship between the depth of penetration of the
probe and the compressive strength can only be obtained empirically because
the penetration of the probe depends on a complex mixture of tensile, shear,
frictional, and compressive forces [37]. The estimation of compressive
strengths with the Windsor Probe, therefore, must be made using a correlation
diagram with appropriate confidence limits.
80
The probe technique appears to be gaining acceptance as a practical NDE
method for estimating the compressive strength of concrete. Improved
correlations between probe results and in-place strength can be obtained by
keeping the curing conditions of the test specimens close to those expected
for in-place concrete, and by making sure that the test concrete is representa-
tive of the in-place concrete. If the Windsor Probe is calibrated using concrete
specimens taken from an early construction stage, the calibration chart could
be used to estimate the strength of concrete placed during later stages
(assuming that the concrete design is the same).
Advantages
The Windsor Probe equipment is simple, durable, requires little maintenance,
and can be used by inspectors in the field with little training. The probe test
is very useful in assessing the general quality and relative strength of
concrete in different parts of a structure.
Limitations
Care must be exercised, however, because a projectile is fired; safety
glasses should be worn. (Note: The gun can only be fired when it is pushed
against the spacer plate.) The Windsor Probe primarily measures surface and
subsurface hardness; it does not yield precise measurements of the in situ
strength of concrete. However, useful estimates of the compressive strength
of concrete may be obtained if the probe is properly calibrated.
The Windsor Probe test does damage the concrete, leaving a hole of about
0.32 in. (8 mm) in diameter for the depth of the probe, and may cause minor
cracking and some surface spalling. Minor repairs of exposed surfaces will
be necessary.
81
5.22 Proof Load Testing
Principle of Method
Proof load testing is based on the concept that a structure capable of
surviving the stresses of a severe overloading should be serviceable under
normal operating conditions [19]. Proof loading requires overloading a
structure in a load pattern similar to operating conditions (e.g., high
pressure in a pipeline).
Applications
Proof load testing can be used with leak testing (see Section 5.11)
in pressure vessels and pipelines inspection to increase the sensitivity of
leak detection. This method is generally used as a last resort to determine
the adequacy of a structural system.
Advantages
An entire structure can be tested in its "as-built" condition.
Limitations
The test may cause the premature failure or the destruction of a
structure. Proof load testing requires extensive planning and preparation,
and is usually expensive.
5.23 Pull-Off Test
The pull-off test is used to estimate the in situ strength of concrete.
Description of Method
The pull-off test, used as a means of predicting the compressive strength
of concrete, involves bonding a circular steel probe, 2 in. (50 mm) in diameter,
82
to the surface of the concrete to be tested [38]. The concrete surface should
be properly prepared and epoxy resin used to bond the probe to the concrete.
A tensile force is applied to the adhered probe using a portable mechanical
system; the force is increased until the concrete fails in tension. From the
tensile force at failure, the compressive strength of the concrete can be
determined from calibration graphs based on data from a large number of pull-
off tests and corresponding cylinder compressive strength tests. Since the
tensile strength of the bonded area is greater than the concrete, the concrete
will eventually fail in tension. The amount of overbreak is usually small so
that the area of failure can be taken as being equal to that of the probe.
Advantages
The procedure is simple, inexpensive, and does not require a highly
skilled operator to make the measurements. Tests can be conducted on horizontal
and vertical surfaces. The stress at failure is a direct measure of the
tensile strength. Inspection of the probe after test will indicate if failure
occurred in the concrete, thus unsatisfactory failures can be discounted. It
is not necessary to plan the location of the test areas in advance of placing
the concrete; as is the case for some other partially destructive tests.
The internal concrete strength can be estimated by partial coring to the
desired depth and conducting the test on the cored area.
Limitations
Although considerable testing has been done and the tests gave consistent
and reliable results, a standard test such as an ASTM test has not been
developed. The concrete needs to be repaired in areas where the test was
conducted.
83
5.24 Radar
Radar is capable of rapid nondestructive assessment of materials such as
asphalt, concrete, soil, and rock by penetrating them to varying depths to
indicate material changes, separations, voids, and other discontinuities [39].
Radar may also be used to estimate material quality.
Description of Method
Radar techniques are based on the principle that electromagnetic waves
are reflected by concrete and other materials. Radar wavelengths can be
longer than those associated with NDE microwave inspections. Portable
equipment is available commercially for application to assessment of concrete,
but the method has yet to be standardized. The radar technique has been
used with success in New York and New Jersey to evaluate concrete pavements
and bridge decks [40]. An attractive feature of this technique is the speed,
approximately 17 km/h, at which pavements can be scanned. It is noted that
great planning and skill are needed to evaluate the data.
The frequencies of the electromagnetic energy selected for radar NDE
inspections range from 100 to 1200 MHz depending on penetration depth and
resolution desired. The resolution or ability to differentiate closely spaced
objects is a function of the signal frequency and bandwidth. Very small
changes over short distances require a higher frequency and wider bandwidth.
With lower frequency and narrower bandwidth, the ability to see small changes
is lessened but the depth of penetration is greater. The energy travels
through different materials at a specific speed for each material depending
on the material's dieletric properties. As an example, at a frequency of
1200 MHz and in 1 nanosecond, the radar wave will travel 6 in. (152 mm) in air,
84
2.5 in, (64 nnn) in concrete, and 3 in, (76 mm) in asphalt. When a change in
material dieletric occurs such as at an interface of air to asphalt or asphalt
to concrete it is indicated by a change in wave shape.
Low frequency radar is used for macro-studies, such as soil mapping and
location of material changes in the subsurface. In micro-studies, higher
frequency radar is used for locations of voids or delaminations in thin
sections such as roadways and bridge decks.
Advantages
Radar can rapidly scan pavements and bridge decks. The data can be
stored and compared with perodic scans to determine changes which occur with
time.
Limitations
Skill is required in interpretation of data to determine with a reasonable
degree of confidence the condition of materials with regard to voids, cracks,
and delamination. Further development work is required if the radar method
is to become a reliable field NDE method.
5.25 Radioactive Methods
There are two types of radioactive NDE methods, radiography and radiometry,
used to assess the properties of in situ concrete and other materials. The
radiography method uses a radioactive source in order to take a graphic picture
of the interior of building components. The radiometry method involves
detecting the intensity of the emerging radiation which passed through a
building component. Prior calibration charts can be used to determine in situ
density of building components and their thickness. Internal defects and
85
location of Internal parts In building components can be determined using
both radiography and radiometry methods. A British standard (BS 4408, Part 3,
1970) outlines testing procedures with regard to gamma radiography.
5.25.1 Radiography
Radiography allows the internal structure of a test object to be inspected
by penetrating radiation, which may be electromagnetic (X-ray, gamma rays, etc.)
or particulate (neutrons) [2,41,42]. The object is exposed to a radiation
beam, and the intensity of the radiation passing through is reduced according
to the object's variations in thickness, density, and absorption characteristics,
The quantity of radiation passing through the object is measured and used to
deduce internal structure. X-rays and gamma rays have been most widely used.
5.25.2 X-ray Radiography
X-rays are produced by bombarding a target material with fast moving,
high energy electrons. The high energy electrons collide with electrons in
the target, which are promoted to higher energy levels. As the promoted
electrons return to their ordinary energy levels, their excess energy results
in the emission of X-rays. X-rays are generated in an evacuated chamber
(X-ray tube) in which high energy electrons are generated by applying a very
high voltage between an incandescent filament (the electron source) and the
target material. By varying the voltage. X-rays with different penetrating
abilities can be generated. For example, for routine Inspections using
exposures of several minutes duration and with medium speed film, 200 kV
X-rays are capable of penetrating about 1 in. (25 mm) of steel, while 400 kV
X-rays can penetrate up to 2 in. (51 mm) of steel [25], which is generally
about the maximum radiation emitted with portable equipment. Recent
86
developments, such as linear accelerators can speed up and Increase the
penetrating power of field radiographic methods [14]. In general, the
penetrating ability of X-rays of a given energy level decreases as the
thickness or the density of the object increases,
5.25.3 Gamma Radiography
Gamma rays are physically indistinguishable from X-rays; they differ
only in the manner in which they are produced [14]. Gamma rays are the
result of radioactive decay of unstable isotopes. Thus, there are some
basic differences between gamma ray and X-ray radiography. Because gamma
rays are produced by nuclear disintegrations, a gamma ray source will lose
its intensity with time. In addition, each source produces rays of fixed
penetrating ability. Isotopes of thulium, iridium, cesium, radium and cobalt
have been used for radiography. Thulium has a penetrating ability of 0.5
in. (13 mm) of steel, while cobalt produces gamma rays capable of penetrating
up to 9 in. (230 mm) of steel. The gamma sources usually used for inspecting
concrete are given in Table 14. Note that the relative penetration abilities
of the gamma rays are controlled by their energies.
87
Table 14
Gamma Ray Sources [41]
Gamma Optimum WorkingRadioactive Energy Half-life Thickness of
Source (MeV) (tl/?) Concrete (mm)
Iridium 192 0.296and
0.613
70 days 30-200
Cesium 137 0.66 33 years 100-300
Cobalt 60 1.17
and
1.33
5.3 years 150-450
Dose Rate*
0.55
0.39
1.35
* Roentgens per hour per curie at 1 m. One curie is equal to 3.7 x 10^^
disintegrations per second.
Portable gamma radiography units are available for field inspections.
Using iridium-192 or cobalt-60 in these units enables short exposure times
and good image sharpness in field applications.
Principles and Applications
Gamma and X-ray radiation is attenuated (reduced) when passing through
materials. The extent of attenuation depends on the density and thickness of
the material, and on the energy of gamma rays. In radiography, differences
in radiation attenuation produced by variations in the density and thickness
of a material are recorded on photographic film. For example, when reinforced
concrete is radiographically inspected, steel reinforcement attenuates the
radiation more than concrete and appears as a lighter area in the film.
Voids and cracks in the concrete appear as darker areas on the film because
the incident radiation is attenuated little.
88
In practice, penetrating rays generated by a suitable source are allowed
to pass through materials, with the emerging radiation being recorded on X-
ray film held in a light-tight cassette. Some of the applications of gamma
radiography are inspecting concrete to locate reinforcing bars, and to
determine if excess microscopic porosity or macroscopic voids are present [43];
inspecting welds for cracks, voids, and slag inclusion; and inspecting masonry
walls for the presence of reinforcement or grout.
Advantages
Radiography provides a method for readily characterizing the internal
features of an in-place material or building component. This method is
applicable to a variety of materials.
Limitations
The most important drawback of radiography is the health hazard associated
with the penetrating radiation. The relatively high cost is another limiting
factor in the use of gamma radiography. A radiographic inspection program
should be planned and carried out by trained individuals who are qualified to
perform such inspection. All personnel involved in radiographic inspection
must carry devices that monitor the radiation dosage to which they have been
subjected, and must be protected so that the dosage rate does not exceed
Federal limits. Gamma ray sources are Inherently hazardous because they emit
rays continuously, and high energy sources have extremely high penetrating
ability. As a result, gamma ray sources require large amounts of shielding
material; this limits the portability of gamma radiography equipment. The
use of gamma-producing isotopes is closely controlled by the Nuclear Regulatory
Commission; users must have a license.
89
5.25.4 X-ray Fluorescence Analyzer
Principle and Applications
This method is generally carried out in the laboratory but there has
been some limited use in the field. The basis of the x-ray fluorescence
technique lies in the relationship between the atomic number and the wavelength
of the x-ray photons emitted by the sample element. Although almost any high
energy particle can be used to excite characteristic radiation from a specimen
in the laboratory, application of an x-ray source offers a reasonable compromise
between efficiency, stability and cost. Almost all commercial laboratory x-
ray spectrometers use an x-ray source. "Since primary (source) x-ray photons
are used to excite secondary (specimen) radiation, the technique is referred
to as x-ray fluorescence spectrometry" [44].
In the potential NDE field method, the material is irradiated with a
radioactive isotope and absorbed energy is re-emitted as x-rays characteristic
of elements present in the material. The method is used for determination of
the elements present in a material.
Advantages
The potential NDE field method provides for a rapid analysis to
determine elements present in installed materials. The analyzer is portable
and can be used in the field and the laboratory.
Limitations
Field analysis is limited to small regions of material per test and the
technique is not capable of detecting all elements. The field apparatus
requires periodic calibration with reference standards.
90
5.26 Seismic Testing
Principle of Method
Seismic testing is the evaluation of material integrity by analysis of
shock wave transmission rates and effects [19], An array of sensing devices
around an explosive charge of known energy (the most common shock load input
system) is used to record shock wave transmission rates. These rates can be
related to material densities. Vibrational patterns induced from shock load-
ing can be used to determine resonant frequencies in structures.
Applications
Seismic testing can measure soil densities and locate density variation
boundaries. Soil density values can then be related to load bearing capacities
and foundation preparation requirements. Seismic testing can also be used to
check structures for possible resonant frequencies that could cause failure
under operating dynamic loads.
Advantages
All components of some seismic test systems are portable.
Limitations
Seismic testing is applicable only to monitoring soil conditions and
structural vibrations. Multi-channel recording systems, power cables, and
many sensing devices are needed. The hazards of explosives are also involved
in the testing.
91
5.27 Soil Exploration
5.27.1 Cone Penetration Test
Principle and Applications
The Cone Penetration test is described in ASTM Standard D 3441. It is
widely used in European practice and is gaining increasing popularity in the
United States [45]. The test is performed by pushing a cylinder having a
conical tip into the ground. The cylinder can be described as having a 1.55
in. 2 (1000 mm^) cross sectional area, a 23.25 in.^ (15,000 mm^) surface
area, and the conical tip has a 60 degree apex angle. The soil resistance
is measured by the resistance to the penetration of the conical tip into the
ground and the frictional forces exerted on the surface of the cylinder
which are measured separately. The cone penetration test has been correlated
both empirically and theoretically with the bearing capacity of deep and
shallow foundations, and with the shear strength, density, stiffness and
compressibility of soils.
5.27.2 Helical Probes
Principle and Applications
Helical probes have been found to be a practical and economic method
for exploring soils at a shallow depth [45]. Test results correlated well
with traditional in situ exploration methods and the probes were also
found to be applicable for compaction control. The probes can be inserted
into the soil to a depth of 6 feet (1.8 m) . The magnitude of the torque
required to insert the helix into the soil is taken as a measure of soil
resistance. The probes can be operated with ease by one person. A probe
could also be coupled with drillrods and used at a greater soil depth.
92
The probes consist of a helical screw connected to a 5-1/2 to 6 foot
(1,7 - 1.8 m) long steel shaft. A hexagonal nut at the upper end of the
shaft is used for applying the torque. The probe is inserted into the ground
by turning it in a clockwise direction using a torquemeter. The torquemeter
has a dial gage to read the torque needed to insert the probe into the soil.
Torque readings are generally taken at 6 in. (15 cm) penetration levels,
however, it is possible to also continuously monitor the torque. The rate of
advance of the probe during a torque reading is kept to correspond to
approximately 4s for a 180 degree turn of the torquemeter. The average
torque rather than the peak value is recorded. Upon completion of the in
situ soils test, the probe is withdrawn by turning it in a counter clockwise
direction.
Limitations
Although extensive testing indicated that the probe test results correlated
well with traditional in situ exploration methods, it was recommended that
research be continued [45], Additional data are needed for controlled conditions
and for soils whose characteristics are well defined. There is also a need
for more data for clays and for compacted fills.
5.27.3 Standard Penetration Test
Principle and Application
The Standard Penetration test is described in ASTM Standard D 1586. It
was developed in 1927 and is the most widely used soil exploration test in
the United States and in worldwide geotechnical engineering practice [45]
.
The test involves dropping a 140 Ibm (63.5 kg) hammer from a height of
93
30 in. (0.76 m) to drive a drillrod with a standard split-tube sampler into
the ground. The number of blows to achieve a 1 ft (0.30 m) penetration by the
split-tube sampler, is used as a measure of soil resistance. The Standard
Penetration test has been empirically correlated with many soil characteristics,
including allowable bearing capacity of foundations, in situ shear strength,
density, stiffness and compressibility, and liquefaction potential during
earthquakes.
5.28 Surface Hardness Testing
Surface hardness methods are generally used to indicate the strength level
or quality of a material rather than to detect flaws. Hardness in these
tests refers to the resistance a material offers to indentation by an object.
Indentation is produced under static or impact loading conditions. The most
common applications are in testing metals and concrete.
5.28.1 Static Indentation Tests
Static indentation tests are primarily used in testing metals. They
usually involve indenting the surface with an indenter of fixed geometry under
specified loads [2]. The indenter has a small point and thus at the point of
contact produces stresses high enough to cause the metal to yield. A permanent
indentation results. The magnitude of the indentation will depend on the
hardness of the metal, the applied load, and the geometry of the indenter.
Therefore, by measuring the size of the indentation under a given set of
conditions, one can get an approximate measure of the hardness. For some
metals such as hardened and tempered steel, the hardness value can be used
to predict with resonable accuracy the tensile strength, impact resistance.
94
and endurance limit [2]. Portable hardness testers are available for in-place
testing of metal structures.
Standard Methods
There are three widely used methods for hardness testing of metals. The
Brlnell method involves applying a constant load (500, 1500, or 3000 kg) on a
0.4 in. (10 mm)-diameter hardened steel ball-type indenter, and measuring the
diameter of the indentation with a microscope. A hardness number is determined
by substituting the values of the applied load, ball diameter, and indentation
diameter into a standard formula. An example of a Brinell test result would
be 400 HB; 400 is the number calculated from the standard formula, "H" stands
for hardness, and "B" for Brinell. For softer metals, one would use a smaller
load to cause the indentation.
The Vickers method is similar to the Brinell method, except that a square-
based, pyramidal diamond indenter is used, and the applied loads are much
smaller. The diagonal of the square indentation is measured, and its value
and the applied load are substituted into a standard equation to calculate
the Vickers hardness number (HV).
The most common method is the Rockwell hardness test, which measures the
depth of additional permanent indentation that occurs as the load is increased
from a small load to the test load. The test instrument measures the depth
automatically, and the hardness number is read directly from a scale on the
instrument. The Rockwell test can be performed much faster than the previously
described methods. There are 15 Rockwell hardness scales — five different
indenters and three different loads. A hardness number of 60 on the Rockwell
95
C scale would be designated 60 HRC. The variety of scales permits testing a
wide range of metals from very soft to very hard.
Usefulness of the Hardness Number
Tables are available that permit conversion of the hardness number from
one test method to the equivalent number of another test method, for example,
see ASTM Standard E 140 (Appendix D) . There are also tables which give the
approximate tensile strengths of metals corresponding to the different hardness
numbers. Care must be taken in using the strength tables because each applies
to only certain types of metals.
5.28.2 Rebound Hammer Method
The rebound method is based on the rebound theories of Shore [46], He
developed the Shore Scleroscope method in which the height of rebound of
a steel hammer dropped on a metal test specimen is measured. The only
commercially available instrument based on the rebound principle for testing
concrete is the Schmidt Rebound Hammer [47],
The technique has gained wide acceptance by researchers and concrete
inspectors. It is one of the most universally used nondestructive test
methods for determining the in-place quality of concrete, and for deciding
when forms may be removed. According to Clifton, standards have been
drafted in Poland and Romania for the rebound hammer [48]. The British
Standards Institution has issued Building Standard 440 which covers non-
destructive test methods for concrete, and includes the rebound hammer method
in part 4 of the Standard [48]. The ASTM has issued Standard C 805, which
gives procedures for the use of the rebound hammer (Appendix D),
96
Description of Method
The Schmidt Rebound Hammer consists of a steel weight and a tension
spring in a tubular frame. When the plunger of the hammer is pushed against
the surface of the concrete, the steel weight is retracted against the force
of the spring. When the weight is completely retracted, the spring is auto-
matically released, the weight is driven against the plunger, and it rebounds.
The rebound distance is indicated by a pointer on a scale that is usually
graduated from zero to 100; the rebound readings are termed R-values. The
R-values indicate the hardness of the concrete; the values increase with the
hardness of the concrete.
Each hammer has a calibration chart, showing the relationship between
coiiipressive strength of concrete and rebound readings. However, rather than
placing too much confidence in the calibration chart, users should develop
their own calibration for each concrete mix and each rebound hammer.
Applications
Numerous investigators have shown that there is some correlation between
the compressive strength of concrete and the hammer rebound number [49-51].
There is, however, extensive disagreement about the accuracy of the strength
estimates from rebound measurements [52,53]. Mitchel and Hoagland found that
the coefficient of variation for estimated compressive strength, for a wide
variety of specimens from the same concrete, averaged 18.8 percent [54], Ami
found that the rebound hammer gave a less reliable estimate of compressive
strength than the Windsor Probe [37]. Some investigators have attempted to
establish correlations between the flexural strength of concrete and the hammer
rebound number. Relationships similar to those for compressive strengths
97
were obtained, except that the statistical variations were even
greater [53,55]
Mltchel and Hoagland attempted to correlate rebound numbers with the
modulus of specimens [54], They concluded that no valid correlations could be
made. Peterson and Stoll, and Klieger have developed some empirical relations
between the dynamic modulus of elasticity and hammer rebound [49,56].
Advantages
The Schmidt Rebound Hammer is a simple and quick method for the
nondestructive testing of concrete in place. The equipment is inexpensive,
coating less than $1000, and can be operated by field personnel with a limited
amount of instruction.
The rebound hammer, like the Windsor Probe, is very useful in assessing
the general quality of concrete and for locating areas of poor quality concrete.
A large number of measurements can be rapidly taken so that large exposed
areas of concrete can be mapped within a few hours.
Limitations
The Schmidt Rebound Hammer, however, has recognized limitations. The
rebound measurements on in situ concrete are affected by:
1. Smoothness of the concrete surface2. Moisture content of concrete3. Type of coarse aggregate4. Size, shape, and rigidity of specimen, e.g., a thick wall
or beam5. Carbonation of the concrete surface [10,53,57].
The rebound method is a rather imprecise test and does not provide a
reliable prediction of the strength of concrete.
98
5,29 Thermal Inspection Methods
Thermal inspection includes methods in which heat-sensing devices or
substances are used to detect irregular temperatures. Thermal inspection of
objects can be used to detect flaws and to detect undesirable distribution
of heat during service [14], There are several methods for carrying out
thermal inspections and many types of temperature measuring devices and
substances. The two main types of thermal inspection are thermography and
thermometry. Thermography involves mapping of isotherms, or contours of equal
temperature, over a test surface; while thermometry is the measurement of
temperature. Both of these methods can be conducted by means of contact and
noncontact inspections. The most commonly used materials or substances for
contact thermographic inspections are heat-sensitive paints, heat-sensitive
papers, thermal phosphors, and liquid crystals. Infrared detectors are used
for noncontact thermographic inspections. There are several basic thermal
detectors used for contact thermometric inspection and they include bolometers,
thermistors, thermocouples, and thermopiles. Surface temperature can be
measured by noncontact thermometric inspections using radiometers and
pyrometers or infrared thermometers.
The presence of discontinuities in an object, such as cracks, voids, or
inclusions, will change the heat transfer characteristics of the object. Thus,
if there is a transient heat flow condition, there will be nonuniform surface
temperatures. The pattern of the surface temperatures can be used as an
indirect indicator of subsurface anomalies [2]. Thermal inspection can also
detect anomalous operating characteristics of a system, such as overloaded
electrical wiring or heat loss through walls and roofs of buildings. The
following discussion addresses primarily the application of thermal inspection
99
to detect anomalies in the internal structure of test objects such as structural
metallic components and roofing systems.
Principle of Thermal Inspection
To establish the condition for thermal inspections, a temperature gradient
must exist or be created in the test object. If necessary, this can be done
by applying a temporary heat source to the front or back surface of the test
object. The flow of heat from the warm to the cold surface will be affected
by the material's thermal diffusivity, which is a function of the material's
thermal conductivity, density, and specific heat. If there are discontinuities
which have thermal diffusivities different from that of the bulk, material,
local "hot" or "cold" spots will exist on the surfaces directly over the
location of the voids. Therefore, by measuring the pattern of surface
temperatures under heat flow conditions, subsurface flaws can be detected.
As stated above, surface temperatures can be determined by contact or
noncontact inspection methods. With contact methods, the surface is covered
with a temperature-sensitive material, and differences in surface temperature
are recorded as a pattern on the coating material. Examples of coatings
developed for this application are: heat sensitive paints and papers; phosphor
coatings for which the fluorescence, under ultraviolet light, is affected by
temperature; melting point coatings which melt when a specific temperature is
reached; and liquid crystals which change color as their temperatures vary.
Contact methods are generally not very sensitive, have relatively long response
times, and require an application procedure before thermal inspection.
Noncontact methods permit remote sensing of the thermal patterns, and are the
more popular thermal inspection methods.
100
5.29.1 Infrared Thermography
Principle of Method
An object having a'^temperature above absolute zero will radiate
electromagnetic waves. The wavelengths of the radiation fall within certain
bands, depending on the temperature. For example, at room temperature, the
wavelengths are typically from 4 to 40 micrometers, with a peak wavelength of
about 10 micrometers [2]. At very high temperatures, the wavelengths of the
emitted radiation are reduced to less than 1 micrometer and fall within the
visible spectrum, which explains why some metals give off a red color when
heated to high temperatures. The longer wavelength radiation associated with
room temperature is not visible to the eye. This is infrared radiation. By
using instruments that can detect infrared radiation, differences in surface
temperatures can be "seen." This is the basis of the thermal inspection
method known as infrared thermography.
The rate of radiant energy emission per unit area of surface (W) is given
by the Stefan-Boltzmann Law:
W=eaT^
where: T = the absolute temperaturee = the emissivitya = the Stefan-Bolt zmann constant (5.67 x lO"!^ watt/cm2/°K^)
.
Thus, changes in the temperature of a surface produce more than proportional
changes in emitted energy, and this allows the testing equipment to detect
temperature differences as small as 0.2°C. Emissivity refers to the efficiency
of energy radiation by the surface. The maximum radiation efficiency occurs
in a "black body," and this is given an emissivity value of 1. All real
surfaces have an emissivity less than 1; polished metallic surfaces have low
emissivity, while roughly textured nonmetals have high emissivity. Since
101
detection methods are based on the intensity of emitted radiation, a change
in emissivity at various points on the surface may be incorrectly interpreted
as a change in temperature. Surfaces with nonuniform or low emissivity can
be painted with high emissivity coatings.
Remote Inspection
Infrared thermography permits remote inspection of the test object.
This is possible because air is practically transparent to the infrared
wavelengths associated with conditions near room temperature [28]. However,
high water content will reduce the transmission of infrared radiation through
air, so problems may arise when the weather is humid. Semiconductor
crystals are most often used to detect infrared radiation. Their electrical
properties are altered by incident infrared radiation. For best sensitivity,
the crystals should be kept cold with liquid nitrogen. This places some
limitations on the portability of the detection systems. Dewar flasks are
needed to hold the liquid nitrogen, and the nitrogen needs to be replaced as
it evaporates.
Infrared Scanners and Display
Operating on a scanning principle similar to television, infrared scanners
allow the user to view a picture of the test object's surface. Through a
system of special mirrors, the surface is scanned, a small spot at a time;
the intensity of radiation is measured by the detector and is displayed on a
cathode ray tube. The horizontal and vertical scans occur so quickly that a
picture (thermogram) of the surface is reconstructed on the cathode ray
tube. The picture is presented as shades of gray corresponding to variations
in surface temperatures of the viewed object. A calibration strip is also
102
shown so that the shades can be converted to absolute temperatures if desired.
It is also possible to have a color display showing different temperatures
in different colors.
Applications
Thermal inspection methods have been applied for detecting disbonds in
laminated materials, entrapped moisture, material density gradients, and
anomalies in castings [2]. In the construction area, infrared thermography
has been applied to compare thermal resistances of roofs, to detect water
penetration into built-up roofs, to detect heat loss through walls and roofs
of buildings, and to detect overloaded electrical circuits [28]. Infrared
thermography has also been used to detect deteriorated regions in bridge
decks [58].
Advantages
Thermal inspection equipment is generally portable, and a permanent record
(photograph) can be made of the inspection results. By using infrared
thermography, inspections can be performed without direct contact with the
surface, and large areas can be rapidly inspected.
Limitations
In determing the size and location of detectable flaws, it should be
recognized that under heat flow conditions the surface temperature patterns
will be a function of the type and size of the discontinuity, its distance
from the surface, the heat intensity applied or flowing to the surface of
the object, and the observation time [2]. The sensitivity of infrared
thermography in detecting internal flaws is a complex function of these
103
variables. Therefore, the results of such inspections should be carefully
interpreted.
5.29.2 Envelope Thermal Testing Unit
Principle and Applications
The envelope thermal testing unit consists of two blankets which are
attached to opposite sides of walls and through which the heat flux to opposite
wall surfaces can be controlled [5]. This testing unit was developed by the
Lawrence Berkeley Laboratory in order to evaluate the in situ transient
thermal performance of walls. It was designed to overcome some of the
difficulties in using heat flow meters and calorimeters for the in situ
evaluation of building components. The difference between the envelope
thermal testing unit and these techniques is that the heat flow is controlled
and not the temperature.
The slightly flexible blankets made to conform to slight irregularties
in wall surfaces are placed in direct thermal contact with the wall, thus
eliminating complications associated with air film and considerably reducing
the bulk of the unit. Each blanket consists of two large area electric
heaters separated by a low-thermal-mass insulating layer. An array of
temperature sensors is embedded in each heat layer. The electric heaters are
designed to provide heat output that is uniform over the entire area and the
heat output is controlled by adjusting the voltage applied to the heaters.
In calculating the thermal resistance of a wall, the data are analyzed in
the manner as the data obtained from heat flow meters and calorimeters.
104
Limitations
The envelope thermal testing unit has been used only for research purposes
and is considered as being under development. Only qualified technicians
experienced with this procedure and also having an understanding of the
fundamentals of building heat transfer should carry out this procedure.
5.29.3 Heat Flow Meter
Principle and Applications
A heat flow meter consists of a thin flat wafer, either circular or
rectangular in shape, that is comprised of a series of pairs of thermocouple
junctions [59]. The wafer contains an embedded thermopile which produces
a voltage (millivolt) signal that is proportional to the rate of heat flow
passing through the wafer. The sensitivity of a heat flow meter (millivolts
per Btu/h ft^) is a function of its average temperature. "In selecting a
heat flow meter for a particular application, it is Important that the heat
flow meter provide a signal sufficiently large for measurement and resolution
by the readout device at the lowest expected heat flow rate [5].
The thermal resistance of a building component can be measured by using
a heat flow meter spot-glued to a representative location on the interior
surface of the component, and temperature-sensing probes attached to the
inside and outside surfaces at the same location. After the heat flow meter
is bonded to the surface, it should be covered with the same or similar
coating used on other parts of the surface, so that the radiative exchange
between the monitored location and other surfaces in the room will be
comparable. The measured thermal resistance of the component is determined
by dividing the average difference in surface temperature, for a sufficient
105
period of time, by the average heat flow measured during the same time
interval. For accurately calibrated heat flow meters, this technique has
been shown to be accurate to within 6 percent [5], The thermal resistance
measurement is applicable only to the particular spot where the heat flow
meter is attached to the building component. However, when used with a
thermographic survey this technique becomes an effective tool for
assessing the thermal performance of building components.
Limitations
This technique can only be used during periods when there is no reversal
in direction of heat flow. Only qualified technicians should carry out this
procedure. They should be experienced with techniques for making proper low-
level electrical measurements and also have an understanding of the fundamentals
of building heat transfer. If the thermal dynamic response of the building
component is to be determined, graduate level training in mathematics is
needed.
5.29.4 Portable Calorimeter
Principle and Applications
The portable calorimeter is essentially a guarded hot box and is used
for measuring in situ heat transmission through building components. It was
developed by the Building Research Division of the National Research Council
of Canada [5], The calorimeter is an insulated box having five sides; the open
side is sealed against the inside surface of the building envelope component
for which heat transmission tests are to be performed. The temperature inside
the box is kept equal to the indoor temperature of the building enclosure by
means of a thermostatically controlled electric heater. The electric
106
energy supplied to the electric heater is essentially equal to the heat
transmission through the metered area since the reverse heat loss through the
box and edge loss where the box edge contacts the metered surface are
essentially nulled to zero [5], This technique has the advantages that it
provides a minimum disturbance to the measured heat transmission and a
sufficiently large surface area is metered so that the measurements are
representative of the performance of a building component. It is reported
that the accuracy of the technique is about 5 percent [5].
Limitations
Calorimeter measurements should be conducted only during periods when
the outdoor to indoor temperature difference (AT) is greater than 10° F.
Solar heating of walls in the winter season may frequently produce AT less
than 10° F. During the measurement of heat transmission through building
components, the indoor temperature must be thermostatically controlled at a
constant level in order to minimize differences in temperature between the
calorimeter and the room. Also, solar radiation into the building and
conditioned air from a warm air supply must not be permitted to strike the
calorimeter. Only qualified technicians experienced with this technique and
also having an understanding of the fundamentals of building heat transfer
should carry out this procedure.
5.29.5 Spot Radiometer
Description of Method
Spot radiometers can be used to determine qualitatively whether a wall
or other building component is insulated or if insulation voids or other
thermal defects are present. They are hand-held devices used to
107
radiometrically measure the equivalent blackbody temperature of a relatively
small area of a surface [5], Spot radiometers are generally small, light
weight, and most are gun-shaped. They are calibrated by pointing them at a
surface of known temperature and adjusting a meter so that the device
radiometrically determines the correct temperature of the reference surface.
Manufacturers often provide reference surfaces having approximately black
body characteristics (i.e., reflecting little radiation from surrounding
surfaces) for calibration purposes. Interior surfaces of buildings generally
have emittances which range from about 0.80 to 0.95. Since the emittance of
an interior wall surface to be measured may differ from the reference surface,
the apparent surface temperature determined using a spot radiometer may
differ from the actual surface temperature by a small amount [5].
In using the spot radiometer, it is pointed at the surface for which
temperature is to be measured and the on-off trigger is depressed. The device
senses the total infrared radiation over a particular wavelength band emanating
from the surface, including both the self-emitted surface radiation and
reflected radiation from surrounding surfaces. The device is calibrated to
read the apparent radiance temperature on either a digital or meter display.
The apparent radiance temperature is defined as the temperature of a perfectly
black surface (emittance =1) which would radiate the same amount of thermal
radiation as the self-emitted and reflected radiation emanating from the
real surface at its actual temperature and having a surface emittance different
from unity. The devices generally have their principal spectral response
in the range of 10 microns, and a response time less than 2 seconds. Contact
with the surfaces to be measured is not necessary with these devices.
Operation close to a wall or building component will indicate apparent surface
108
temperature of a small region, while operation at a distance will indicate
apparent surface temperature for a larger region. Spot radiometers may be
equipped with an audio device that will produce a change in audible tone when
a thermal anomaly such as an air infiltration path or missing insulation is
found while scanning a wall or building component. Gross thermal defects can
be readily detected while quickly scanning the envelope of a building.
Limitations
This technique is not sensitive enough to permit detection of small
diffrences in effectiveness of insulation such as to distinguish an R-13 wall
from an R-15 wall.
5.30 Ultrasonic Pulse Methods
In the ultrasonic pulse methods, sound waves which are beyond the audible
range are induced in a test object by a piezoelectric transducer, and either
reflected waves or those passing through the object are detected by a similar
type of transducer [2,10,60-63]. When reflected waves are detected, the
technique is called "pulse-echo," and the transmitting transducer may also
act as the receiver. Waves passing through the object are detected with a
second transducer, i.e., a receiving transducer.
Ultrasonic inspection is based on two principles: (1) the velocity of
the acoustic waves in a material is a function of that material's elastic
constants and density; and (2) when an acoustic wave encounters an interface
between dissimilar materials, a portion of the wave is reflected. The amount
of reflection depends on the mismatch in acoustic impedance (product of wave
velocity and density) of the materials, with the amount of reflection increasing
with the mismatch.
109
5.30.1 Ultrasonic Pulse Velocity
The ultrasonic pulse velocity method is one of the most universally used
NDE methods for assessing the quality of concrete.
Principle of Method
The ultrasonic pulse velocity method measures the travel time of an
ultrasonic pulse passing through a material. The pulse generated by an
electroacoustic transducer is picked up by a receiver transducer and in some
cases the pulse may be amplified. The time of travel of the pulse is
measured electronically [63].
When a mechanical pulse is applied to a material by an electroacoustic
transducer, waves are induced in the material. Longitudinal waves are used
most often in testing concrete. These waves are transmitted by particles
vibrating parallel to the direction of propagation. The waves' velocity,
controlled by the elastic properties and the density of the material, is
virtually independent of the geometry of the object being tested.
If a longitudinal wave encounters a discontinuity such as crack or void,
it may "bend," i.e., be diffracted around the discontinuity. This increases
the internal distance the wave must pass between the transmitting and pickup
transducers, and consequently its travel time increases. The travel time of
a longitudinal wave will also be affected by changes in density and elastic
properties of a given concrete along the travel path.
Several ultrasonic pulse velocity units are commercially available for
testing concrete; these cost about $4000. Some models can be used to test
concrete as thick as 75 ft (30 m)
.
110
Application for Assessment of Condition of Concrete
The ultrasonic pulse velocity method Is best for nondestructive evaluation
of the uniformity of in-place concrete. (ASTM Standard C 597 gives the
standard test procedure, see Appendix D). For example, velocity measurements
have been successfully used to detect deteriorated regions In concrete bridges
and to check the uniformity of concrete in walls. In general, if substantial
variations in pulse velocities are found in a structure, without any apparent
reason (such as intentional changes in materials, concrete mix, or construction
procedures), this indicates that the concrete is unsound.
A general rating which has been proposed to assess the relative quality
of concrete is presented in Table 15 [64]. These criteria should be used with
caution because differences in the qualities of concrete cannot be as sharply
delineated as indicated in Table 15. In addition, velocity is affected by
the density and amount of aggregate in the concrete. A crude assessment of
the quality of similar types of concrete can be made, however, using these
criteria. For example, if one concrete has a pulse velocity of 15,000 ft/sec
(4570 m/sec) , while another concrete with a similar composition has a velocity
below 10,000 ft/sec (3050 m/sec), then there is clearly a significant difference
in their qualities.
Table 15
Pulse Velocities in Concrete [64]
Feet per Second (Meters per Second)
Above 15,00012,000-15,00010,000-12,0007,000-10,000
Below 7,000
(4570)(3660-4570)(3050-4570)(2130-3050)(2130)
General Condition
ExcellentGoodQuestionablePoorVery Poor
111
Estimation of Strength Properties of Concrete
Many investigations have attempted to correlate compressive and flexural
strengths of concrete with pulse velocity [63]. Some correlations have been
obtained in laboratory studies, provided that mix proportions, the cement,
types of aggregate, and curing conditions were not varied. If these factors
were altered, however, no usable correlations were obtained. For example,
Parker [65] compared pulse velocities and compressive strengths for concretes
made from only one type of aggregate, but containing different cements from
different sources and a variety of admixtures. His analysis of the data
indicates that at the 95 percent confidence level the estimated strength of
4440 psi (30.7 MPa) concrete ranged from about 2100 to 6000 psi (14.5 to 41.8
MPa). Obviously, the ultrasonic pulse method cannot be used to obtain reliable
estimates of compressive strength when the composition of concrete in a
structure is unknown.
Jones has offered these concluding remarks regarding strength
prediction from wave propagation methods: "In spite of some of the promising
results of the early investigations, it must be concluded that no general
relation has been found between the dynamic modulus of elasticity and its
flexural or compressive strength" [66]. This statement still holds if one
substitutes "pulse velocity" for "dynamic modulus of elasticity."
Extraneous Effects on Velocity Measurements
The measurement of the pulse velocity of concrete is affected by several
factors which are not intrinsic properties of concrete, and, therefore, are
not a function of the quality or strength of concrete [10], These factors include:
112
1, Smoothness of concrete at transducer contact area. Good acoustical
contact between the transducers and concrete is required. In addition, a
coupling agent such as an oil or a jelly must be used.
2. Concrete temperatures outside the range between Al° and 86°F (5° and
30° C) affect the measured pulse velocity. Below this temperature range, the
velocity is increased, and above, the velocity is decreased.
3. Moisture condition of concrete. Pulse velocity generally increases as
the moisture content of concrete increases, while compressive strength decreases
as moisture content increases.
4, Presence of reinforcing steel. The pulse velocity in steel is 1.2 to
1.9 times the velocity in concrete. Measurements made near steel reinforcing
bars, therefore, may not be representative of the concrete. If possible,
measurements should be made perpendicular to the longitudinal axis of the bars.
If measurements must be made parallel to the longitudinal axis of the steel
bars, crude correction factors are available.
5.30.2 Ultrasonic Pulse Echo
Principle of Method
In the ultrasonic pulse echo method, waves which are reflected off
discontinuities (e.g., cracks and voids) and from interfaces (e.g., those
between concrete and steel or between concrete and air) are recorded. Both
the transmitting and receiving transducers are contained in the same probe;
thus, only waves which are reflected back at nearly 180 degrees are detected.
The penetrating ability of the ultrasonic pulse and the minimum size of
detectable flaws are influenced by the frequency of the generated waves. High
frequency results in less penetration but better sensitivity than low frequency.
113
Applications
Echo techniques have been extensively used to identify and locate
discontinuities and defects in metals and welds [2,60-62]. The echo technique
is one of the most versatile and accepted NDE methods for metals. However, it
has not been used often with concrete — largely because the extensive pore
system, the presence of cracking, and the heterogeneous nature of concrete
cause multiple reflections when very high frequency pulses are used. Therefore,
the reflected waves are significantly attenuated and the interpretation of the
observations complicated. As noted, the heterogeneous nature of concrete poses
problems not encountered in pulse-echo evaluation of metals, thus, progress
in this area of concrete nondestructive testing has been slow. A review of
research indicates that the pulse-echo method has been used successfully to
detect flaws within concrete, however, standardized methods do not currently
exist for pulse-echo evaluation of concrete structures [67]. Pulse-echo
methods have been used for detection of very large cracks in dams, for
integrity testing of piles and other slender concrete structures, and for
measuring the thickness of slabs and pavement. In addition, it may be possible
to combine the echo method with acoustic impact (see Acoustic Impact Method,
Section 5.2) so that low frequency waves are generated. These would be
insensitive to microscopic flaws but could be used to detect large
discontinuities [68]. Commercial equipment is not yet available for such
testing.
Advantages
Ultrasonic pulse-echo inspection offers several advantages over other NDE
methods — such as gamma radiography — capable of detecting internal flaws in
114
a test object [2]. For example, acoustic waves have excellent penetrating
ability, and with proper Instrument selection, thick sections of 30 ft (10
m) or more can be inspected. Very small flaws may be detected, and their
location and geometry estimated with reasonable accuracy. In addition, test
results are immediately available and the equipment is lightweight and
portable.
Limitations
Because of the indirect nature of flaw detection by ultrasonic pulse-echo
inspection, personnel with a high level of expertise are needed to plan an
inspection program. A thorough understanding of the nature of the interactions
between the acoustic waves and different discontinuities is required in order
to interpret test results properly. The physical testing, on the other hand,
may be performed by technicians after proper training. Before ultrasonic
inspection equipment can be used, calibration and referencing with standards
must be performed; otherwise, test results have no meaning. The nature of the
calibrations will depend on the particular inspection program.
5.31 Uplift Resistance
Description of Method
The resistance of built-up roofing systems to uplift pressure can be
determined using the ASTM Standard E 907 test method (Appendix D) . A controlled
negative pressure is created on top of the roof surface using a chamber, 5 x 5 ft
(1.5 x 1.5 m) in area, fitted with a vacuum pump and a pressure measuring device.
Provisions must be made to provide a smooth surface along the roof to allow the
edges of the chamber to be in complete contact with the roof surface so that a
negative pressure can be applied inside the chamber. For roofs containing mineral
115
aggregate surfacing, the loose surfacing should be removed by sweeping a path
about 12 in. (300 mm) wide and applying a heavy pouring of hot asphalt over
the swept area. When the asphalt cools it will provide the smooth surface
necessary for contact with the chamber. The bottom flanges of the chamber are
equipped with a foam strip to seal the chamber to the roof surface. The chamber
is oriented on the roof so that the edges are parallel with the direction of
the structural framing of the building.
The negative pressure is applied in increments and the deflection is
continuously monitored during the test for sudden or variable rates of movement.
The predetermined increments of pressure are held for 1 minute and further
increments are applied until a preselected negative pressure is reached or
failure (adhesion or cohesion) occurs. Most roof systems subjected to a
negative pressure will exhibit an upward deflection that will increase with an
increase in negative pressure. Poorly adhered roofing systems will exhibit
relatively large increases in upward defections with relatively small
increases in applied pressure. For well adhered roofing systems the increase
in deflection will be gradual and at a relatively constant rate up to a point
at or near failure.
5.32 Visual Inspection
Surface defects often can be detected visually using methods to improve
ordinary observations. Optical magnification or other techniques which can be
used to increase the apparent size of surface cracks are covered in this section.
5.32.1 Optical Magnification
Available magnifying instruments range from simple, inexpensive glasses
to expensive microscopes. Some fundamental principles about the operating
116
characteristics of magnification instruments should be understood before a
system is chosen for a particular application. For example, the focal length
decreases as the magnification power increases. This means that when high
magnification is desired, the primary lens must be placed close to the test
object. The field of view (the portion of the object that can be seen at any
instant) also decreases as magnification power increases. A small field of
view means that it will be tedious to examine a large surface area. Another
important characteristic is the depth of field — the elevation difference of
rough textured surfaces that can be viewed in focus simultaneously; the depth
of field decreases as the magnification power of the instrument increases.
Therefore, to inspect a rough-textured surface, a magnification power should be
selected that gives a large enough depth of field so that the "hills" and
"valleys" are simultaneously in focus. Finally, the illumination intensity
required to clearly see surface flaws will increase as the magnification power
increases. High magnification may require a light source to supplement
the available lighting.
A useful tool for field inspection is a pocket magnifier with a built-in
viewing scale, which allows measurement of flaw dimensions. A stereomicroscope
is very useful when a three-dimensional view of the surface is required. With
this instrument, one can determine whether a wide crack is shallow or extends
deep into the object. If calibrated, a stereomicroscope can also be used as a
depth gage to measure the approximate height of surface irregularities.
5.32.2 Fiberscope
Another useful instrument is the fiberscope, which is composed of a bundle
of flexible optical fibers and lens systems. The fiberscope can be inserted
117
through a small access hole so that the inside of a cavity can be seen. Some
of the fibers in the bundle carry light into the cavity and illuminate the
field of view. The viewing head can be rotated so that a wide viewing angle
is possible from a single access hole. A fiberscope, because of the discrete
nature of light transmission of the fibers, may not have as good resolution
as a borescope, which is straight, rigid tube using a lens system for
viewing. The best resolution is obtained with an instrument having small-
diameter fibers in which the fiber density per unit area is high. To use a
fiberscope, one must drill access holes if natural channels are not present,
and the hole must intercept cavities. The acoustic impact technique
(Section 5.2) can be used to locate hollow spots for subsequent fiberscope
inspection.
5.32.3 Liquid Penetrant Inspection
In this method a highly visible dye is used to coat the surface to be
inspected [2,69]. Any cracks open to the surface will soak up the dye because
of low surface tension and capillary effects. After application of the dye,
the surface is cleaned. However, the dye which penetrated into cracks remains
and reveals the presence of cracks. The method is one of the most inexpensive
inspection tools, but it only permits detection of open flaws on the surface of
the test object.
Description of Method
Dye penetrant inspection involves the following steps: (1) cleaning
the surface, (2) applying the dye, (3) removing excess dye from the surface,
(A) applying a developer, and (5) interpreting the results.
118
The objective of the cleaning is to remove foreign matter from cracks so
that the dye can penetrate. The specific procedures depend on the condition
of the surface. Care must be taken to ensure that the cleaning process does
not smear the cracks or fill them with residues. For example, sandblasting a
soft metal may "hammer" the surface so much that cracks become closed and
undetectable.
The dye may be applied to the surface by spraying, painting, or dipping.
Two types of dye are available: one is for viewing under ordinary light and is
usually a brilliant red color, the other is fluorescent and viewed under
ultraviolet light. Fluorescent dyes offer the best sensitivity for detecting
small cracks. The dye is allowed to remain on the surface from 10 to 30 minutes
(dwell time) before the excess is removed.
Cleaning can be done by flushing the surface with water or by wiping with
a rag dampened with solvent. An emulsifying agent is needed so that the dye
can be completely removed with water. The agent is either already included in
the dye, or it is added to the coated surface before washing. This phase is
very important; all excess dye must be removed, otherwise some indications of
cracks will be false. If the surface is very porous, inspection by this method
may be difficult; if dye is not removed from the pores, there will be a loss
of contrast because the surface will take on a color that is a light shade of
the dye. If the dye is removed from all pores, it probably will be removed
from some of the cracks as well.
After cleaning, the surface is allowed to dry, and a developer is added.
Developer is a fine powder which: (1) provides a uniform, colored background
to increase contrast, and (2) has a blotting effect, thereby drawing up the
dye from the cracks. The blotting action increases the apparent width of the
119
cracks so that they are clearly visible. Developer can be applied as a dry
powder or as a paint. The thickness of the developer layer is important; if it
is too thin, there will not be good contrast, and if it is too thick, it may
mask the cracks.
Finally, the prepared surface is inspected. If the application was done
correctly, the cracks will be clearly shown.
However, the inspector needs to be familiar with the patterns associated
with "irrelevant indications," i.e., patterns not from cracks but from other
sources, such as improper cleaning.
Applications and Limitations
Although dye penetrant inspection relies on simple principles, a certain
amount of skill is necessary to carry out do the process correctly. The
operator needs to recognize what materials to use for a particular application,
and to understand how the materials respond to different temperature conditions.
Portable kits are available with the various chemicals in aerosol cans, thus
making field inspection possible. The technology is now geared primarily
toward inspection of metals. The applicability of the procedures to masonry
or concrete structures having surfaces of high porosity has not been demonstrated,
5.33 Water Permeability of Coated Masonry Walls
Principle and Applications
The transmission of water through coated masonry walls is proportional to
the number of "pin holes" in the coating. The exterior coating and its
application are the most significant variables in preventing excessive
permeation into the masonry. A reservoir, about 7 in^ (12 x 10^ mm^)
,
with an open face is sealed to the masonry and kept pressed against the wall
120
by a spring which is stretched between two hooks that are secured to the masonry
wall. The reservoir is filled with water and the water is allowed to permeate the
wall for 15 minutes or the time required to absorb 25 ml of water. The water
absorbed by the wall is determined from a burette connected to the reservoir.
From a measurement of the diameter of the reservoir, the rate of water absorption
can be expressed in gallons per square foot per hour. When the rate of water
disappearance from the reservoir is less than 1 gal/ft^/h there are no damaging
effects. In order to provide a margin of safety, a limit of 1/2 gal/ft^/h was
established [70]. A properly coated masonry surface will have a water transmission
rate of about one-tenth that amount.
5.34 Combinations of Nondestructive Evaluation Methods
While no single NDE method may be entirely satisfactory for predicting the
strength or quality of material, combinations of methods which respond to
different factors may give more definite information. The combined NDE approach
has been developed mainly for evaluating concrete; therefore, only applications
to concrete will be described.
The results of two methods can be combined in a linear equation of the
form:
f^ = A(NDEp + B(NDE2) + C
where f is the estimated compressive strength from the combined method, NDEi
and NDE2 are the results of the individual methods, and A, B, and C are
empirically determined constants.
Two combinations often used are the ultrasonic pulse velocity method and
the measurement of the damping constant of concrete [71], and the ultrasonic pulse
121
velocity and pulse attenuation methods [72]. These combinations are essentially
laboratory research techniques and therefore will not be discussed further.
The most popular combination has been the ultrasonic pulse velocity method
and the rebound hammer [73]. This combination has been used primarily in Europe,
with the most exhaustive studies being carried out by Facaoaru [74-77]. In this
combined approach, measurements of ultrasonic pulse velocity and rebound
number are made on in situ concrete. The pulse velocity and rebound number are
substituted into a previously derived regression equation to predict compressive
strength. It is generally believed that the multiple regression equation
should give a more accurate estimate of compressive strength than either
of the individual measurements alone.
For standard concrete mixes, Facaoaru has developed calibration charts
from which the compressive strengths can be estimated when the pulse velocities
and rebound numbers are known [74]. Correction factors have also been developed
to be used in the case of nonstandard concrete mixes. This combined method has
been used often in Romania to estimate the compressive strength of in situ
concrete [74,76]. Based on his experiences, Facaoaru contends that the combined
method offers the following accuracy in predictions of compressive strengths:
1. When composition is known and test specimens or cores are availablefor calibration purposes, accuracy is within 10 to 15 percent.
2. When only the composition of the concrete is known, accuracy is within15 to 20 percent.
3. When neither the composition is known nor test specimens or cores areavailable, accuracy is within 20 to 30 percent [76],
This suggests that for case 3, the combined method gives no better prediction
of the compressive strength than can be obtained by measuring only the ultrasonic
pulse velocity or only the rebound number; in case 2, the improvement is marginal.
122
I
Therefore, only when the concrete is well characterized is this combined method
better than the individual nondestructive methods.
123
6 . SUMMARY
Nondestructive evaluation (NDE) methods for evaluating In situ
construction materials and condition assessment of building components and
systems were Identified and described. This report Is Intended to help
Inspectors and those Involved In condition assessment choose appropriate NDE
methods for specific building materials, components, and systems. Important
properties of building materials along with Important performance requirements
for building components are listed, and appropriate NDE methods for determining
these properties are recommended. In many cases the advantages and limitations
for the NDE methods are presented. Potential NDE methods which may or may
not require further research and development before they are ready for routine
use were also identified and briefly described. In addition, ASTM standards
for NDE methods for concrete and other building materials and components were
identified.
In a related aspect of the study, current Navy practices relative to the
use of NDE methods in the construction and service cycle of buildings and
other structures were reviewed. This review was based on Navy reports and
documents provided by the Naval Civil Engineering Laboratory (NCEL) and the
Naval Facilities Engineering Command (NAVFAC), and on discussions with NAVFAC
personnel involved with buildings and structures problems where NDE methods
are used for diagnostic purposes. Navy Guide Specifications were examined
for required tests, both NDE and destructive, of in situ building materials
and components. Twenty nine of the 239 Guide Specifications reviewed contained
required NDE tests.
124
7 . ACKNOWLEDGMENTS
This study was sponsored by the Naval Civil Engineering Laboratory
(NCEL) , Port Hueneme California, and the Naval Facilities Engineering Command
(NAVFAC). The authors appreciate the support and assistance of Joseph Berke
(NCEL) and Melvin Hironaka (NCEL) who provided liaison between NCEL and
NBS. The authors also thank their NBS colleagues, James Pielert , Walter
Rossiter, and Leonard Mordfin who gave important review comments on this
report. The authors acknowledge the excellent and extensive support of
Denise Herbert for typing the manuscript.
125
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Concrete by Accelerated Curing and Schmidt Rebound Hammer," Journalof the American Concrete Institute, Vol. 61, No. 1 (1964), p. 1,
51. Victor, D.J., "Evaluation of Hardened Field Concrete with ReboundHammer," Indian Concrete Journal, Vol. 37, No. 11 (1963), p. 407.
52. Greene, G.W. , "Test Hammer Provides New Methods for EvaluatingHardened Concrete," Journal of the American Concrete Institute,"Vol. 26, No. 3 (1954), p. 249.
53. "Discussion of G.W. Green, "Test Hammer Provides New Method of
Evaluating Hardened Concrete," Journal of the American ConcreteInstitute, Vol. 27, No. 4 (1955), p. 256.
54. Mitchel, L.J. and Hoagland, G.G., "Investigation of the Impact-TypeConcrete Test Hammer," Highway Research Board Bulletin 305 (1961),p. 14.
55. Williams, C.H. , "Investigation of the Schmidt Concrete Test Hammer,"Miscellaneous Report No. 6-267, U.S. Army Engineering WaterwaysExperiment Station (1958).
56. Klieger, P., Discussion of P.H. Peterson and V.M. Stoll, "Relationof Rebound Hammer Test Results to Sonic Modulus and Compresslve-Strength Data," Proceedings of Highway Research Board, Vol. 34
(1955), p. 392.
57. Erickson, G.A. , "Investigation of the Impact-Type Concrete TestHammer, Model II," Concrete Laboratory Report C-928, Division ofEngineering Laboratories, Dept. of Interior (U.S.) (1959).
58. Manning, D.G. and Holt, F.B., "Detecting Delamination in ConcreteBridge Decks," Concrete International, Vol. 2, No. 11 (1980),pp. 34-41.
59. Grot, Richard A., Persily, Andrew K. , Chang, May Y. , Fang, Jin B.,Weber, Stephen, and Galowin, Lawrence S. , "Evaluation of the ThermalIntegrity of the Building Envelopes of Eight Federal Office Buildings,"National Bureau of Standards (U.S.), NBSIR 85-3147 (September 1985).
60. Smith, A.L. , "Ultrasonic Testing Fundamentals," Lesson 5, Fundamentalsof Nondestructive Testing, Metals Engineering Institute (1977).
61. Lovelace, J.F. , "Ultrasonic Testing Equipment," Lesson 6, Fundamentalsof Nondestructive Testing, Metals Engineering Institute (1977).
130
62, Moberg, A.J. , "Ultrasonic Testing Applications," Lesson 7, Fundamentalsof Nondestructive Testing, Metals Engineering Institute (1977).
63, Whltehurst, E.A., "Evaluation of Concrete Properties from Sonic Tests,"American Concrete Institute, Monograph No. 2 (1966),
64, Leslie, J,R, and Cheesman, W.J. , "An Ultransonlc Method fo StudyingDeterioration and Cracking In Concrete Structures," Journal of theAmerican Concrete Institute, Vol. 21, No. 1 (19A9), Proceedings,Vol. 46, pp. 17-36,
65, Parker, W.E,, "Pulse Velocity Testing of Concrete," Proceedings of theAmerican Society for Materials and Testing, Vol, 53 (1953), p. 1033.
66, Jones, R, , "Nondestructive Testing of Concrete," Cambridge UniversityPress (1962),
67, Carlno, N.J, and Sanalone, M, , "Pulse-Echo Methods for Flaw Detectionin Concrete," National Bureau of Standards (U,S.), Technical Note 1199(July 1984).
68, Sansalone, Mary and Carlno, Nicholas J., "Transient Impact Responseof Plates Containing Flaws," Journal of Research of the NationalBureau of Standards (U,S.), Vol. 92, No. 6 (November-December 1987),
pp. 369-381,
69, Lomerson, E.G., "Liquid Penetrants," Lesson 2, Fundamentals of
Nondestructive Testing, Metals Engineering Institute (1977).
70, Naval Civil Engineering Laboratory Techdata Sheet 75-31, "MeasuringWater Permeability of Masonry Walls," Port Hueneme, G (December 1975).
71, Wiebenga, J.G. , "A Comparison Between Various Combined NondestructiveTesting Methods to Derive the Compressive Strength of Concrete,"Report No. Bl-68-61/ IHI.8 , In Situ TNG Voor Bouwmaterlalen en
Bouw Constructies, Delft, Netherlands (1968).
72, Galan, A., "Estimate of Concrete Strength by Ultrasonic Pulse Velocityand Damping Constant," Journal of the American Concrete Institute,Vol, 64, No. 10 (1967), p. 678.
73, Jones, R. and Facaoaru, I., "Analysis of Answers to a Questionnaire on
the Ultrasonic Pulse Technique," Materlaux et Constructions/Materialsand Structures, Vol. 1, No. 5 (1968), p. 457.
74, Facaoaru, I,, "Nondestructive Testing of Concrete in Romania," Paper4C, Symposium on Nondestructive Testing of Concrete and Timber, London,Institution of Civil Engineers (1969).
131
75. Facaoaru, I., Dumitrescu, I. and Constaninescu, L. , "Concrete StrengthDetermination by Nondestructive Combined Methods," RILEM Report, Aachen,41 (1966).
76. Facaoaru, I., Dumitrescu, I. and Stamate, G.L. , "New Developments andExperience in Applying Combined Nondestructive Methods for TestingConcrete, RILEM Report, Varna, 26 (1968).
77. Facaoaru, I., "Chairman's Report of the RILEM Committee on NondestructiveTesting of Concrete," Materiaux et Constructions/Materials andStructures, Vol. 2, No. 10 (1969), p. 253.
132
APPENDIX A. REVIEW OF NAVY GUIDE SPECIFICATIONS
The Navy Guide Specifications that were reviewed with regard to NDE in situ
tests of building materials and components are listed in Table A.
Twenty nine of the 239 Navy Guide Specifications listed in this table
contained required NDE tests. The twenty-nine Guide Specifications along with
the NDE tests required for each specification are given in Appendix B.
The tests included in the Guide Specifications are listed for each specification
and they include field tests, laboratory tests, and NDE tests. Some of the
field tests and laboratory tests are of the destructive type.
A-1
Table A. Review of Navy Guide Specifications
Guide Spec. No & Date Guide Spec. Title
1. TS-T18 a
(July 1965)
2. NFGS-02050(March 1984)
3. NFGS-02102(August 1982)
4. TS-02200Amendment-l (November 1980)
Field Tests
• gradation of fillor backfill material
• liquid limit and plasticityof fill or backfill material
• moisture density relationshipof fill or backfill material
• density of in place material• moisture content of in placesoil material (ASTM D 3017)
5. NFGS-02247(March 1983)
Tests
• aggregate or existingsoil aggregate materials-sieve analysis of combinedmaterial-liquid limit-plasticity index
• compressive strength of cementtreated materials
• smoothness of paved area• thickness of base or subbasecourse
Specification for Timber Harvesting
No tests specified
Demolition and Removal
No tests specified
Clearing and Grubbing
No tests specified
Earthwork
NDE Tests
None specified
Portland Cement Stabilized [Base] [or]
[Subbase] Course for Airfields, Roadsand Streets
NDE Tests
None specified
A-
2
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
• field density• laboratory tests
-optimum moisture contentand maximum density
-moisture-density relation-ship of existing soils(for site preparation)
6. NFGS-02250(June 1981)
Soil Treatment for SubterraneanTermite Control
7. NFGS-02361(July 1983)
Tests
• load test of piles
8. TS-02362.3(October 1980)
Tests
• load tests of piles• grout consistency(flow cone test)
• grout compressivestrength
9. NPGS-02363(August 1981)
Tests
• load tests of piles• concrete testing
10. NFGS-02367(August 1981)
Tests
• load tests of piles• concrete testing(aggregates, compressivestrength of concrete)
No tests specified
Round Timber Piles
NDE Tests
None specified
Auger-Placed Grout Piles
NDE Tests
None Specified
Cast-ln-Place Concrete Piling, SteelCasing
NDE Tests
None specified
Prestressed Concrete Piling
NDE Tests
None specified
A-
3
Guide Spec. No & Date
11. TS-02360.1(October 1980)
Table 4. (Continued)
Guide Spec. Title
Round Timber-Concrete Composite Piles
Tests
load tests of piles
NDE Tests
None specified
12. TS-02368(January)
Tests
• load tests of piles
13. NPGS-02369(March 1984)
Tests
• load tests of footings,measure deflection or
settlement
14. NFGS-02369.1(September 1983)
Steel H-Piles
NDE Tests
None specified
Pressure- Injected Footings
NDE Tests
None specified
Sheet Steel Piles
No tests specified
15. NFGS-02452(September 1984)
Tests
• verify gauge, alignment, andsurface elevation of track
16. NFGS-02485(December 1982)
No tests specified
17. NFGS-02490(November 1982)
Railroad Trackwork
NDE Tests
• ultrasonic inspection ofwelded rail joints
Turf
Trees, Plants, and Ground Cover
No tests specified
A-4
Guide Spec. No & Date
Table 4. (Continued)
Guide Spec. Title
18. TS-02513.1(September 1979)
Tests of Pavement Course
• density using cores• thickness• straightedge of compacted surface
19. NPGS-02559(October 1983)
Tests at job site
• slump• air content• temperature of plastic concreteIn-place
• surface smoothness• pavement thickness (core samples);note, cores can also be usedto evaluate condition of the concrete
• flexural strength (from job site beamspecimens)
20. NFGS-02573(March 1984)
Tests
• density using cores• thickness of binder andwearing courses
• smoothness of compacted surfaces• finish grades of each course placed
21. NFGS-02576September 1981
Tests
• slurry mixturewater contentresidual asphalt content
gradation of extracted aggregatecalculate percent of emulsified asphalt
Asphalt Concrete Base Course
(Central Plant Hot Mix)
NDE Tests
None specified
Portland Cement Concrete Pavementfor Roads and Air Fields
NDE Tests
None specified
Bituminous Hot Mix Pavement
NDE Tests
None specified
Asphalt Slurry Seal
NDE Tests
None specified
A-
5
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
• trial application (demonstrateability to apply slurry seal)
22. TS-02577(July 1980)
Field Testing
None specified
23. NFGS-02578(August 1982)
Field Testing
• demonstrate rubber and
paint removal on 50 ft.
long test area• recommended friction and texturetesting after removal work
24. TS-02581(September 1978)
Tests
• measure flow and drawdown
25. TS-02614(January 1978)
Pavement Markings (Airfields andRoads
NDE Tests
None specified
Rubber and Paint Removal fromAirfield Pavements
NDE Tests
None specified
Rotary Drilled Water Well
NDE Tests
None specified
Joints, Reinforcement and MooringEyes in Concrete Pavements
26. TS-02616(October 1979)
27. NFGS-02622.1
No tests specified
Resealing of Joints in Rigid Pavement
No tests specified
Fiberglass Reinforced Plastic (FRP)
Piping (for Petroleum Products)
Field Tests
• initial pneumatic test at a
pressure of 15 psig• second pneumatic test at a pressureof 50 psig
NDE Tests
None specified
A-6
Table A. (Continued)
Guide Spec. No & Date
• hydrostatic pressure test• hydrostatic cycle test of system• operational test of system• backfill density
28. TS-02671(September 1980)
No tests specified
29. TS-02672(September 1980)
Tests
• sulfonatlon Index test for tar• spot test for asphalt
Guide Spec. Title
Bituminous Tack Coat
Bituminous Prime Coat
NDE Tests
None specified
30. TS-02673(September 1980)
Tests
• stripping test• spot test
31. TS-02675(March 1979)
Field Tests
None specified
32. NFGS-02676(February 1982)
33. TS-02677(August 1980)
No tests specified
No tests specified
Bituminous Seal Coat , SprayApplication
NDE Tests
None specified
Coal Tar Seal Coat with UnvulanlzedRubber
NDE Tests
None specified
Fog Seal
Bituminous Surface Treatment
A-
7
i
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
3A. TS-02685(October 1980)
Field Tests
• aggregate gradation• smoothness of top layer• density of each layer of base course• thickness of base course
35. TS-02686(October 1980)
Select-Material Base Course forRigid Pavement
NDE Tests
None specified
Graded Aggregate Base Course forFlexible Pavement
Field Tests NDE Tests
• aggregate gradation• smoothness of top layer• density of each layer of base material• thickness of base course
36. NFGS-02696(November 1981)
Field Tests
• aggregate gradation• smoothness of top layer• density of each layer• thickness of subbase course
37. NFGS-02714(July 1982)
Field Tests
• test system to demonstratecompliance with contract
• before Insulation is applied,hydrostatically test eachpiping system
None specified
Selected-Material Subbase Coursefor Flexible Pavement
NDE Tests
None specified
Exterior Steam Distribution
NDE Tests
None specified i
A-8
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
38. TS-02722(July 1980)
Field Tests
• straightness of pipelines andgross deficiences
• leakage• deflection of plastic pipelines• pressure test of the system• field tests for concrete (Section 03300,"Cast-in-Place Concrete")
slumpcompressive strength (from job-site
cylinders)temperature tests
39. NFGS-02734(March 1984)
Field Tests
• measure flow and drawdown(pump test)
• well plumbness and alignment
40. NPGS-02854(March 1983)
Field Tests
• (visual) inspect new railfittings thoroughly (boltedjoints and welds)
• verify gage, alignment and surfaceelevation of track
41. NFGS-02881(November 1981)
No tests specified
Exterior Sanitary Sewer System
NDE Tests
None specified
Rotary-Drilled Water Well
NDE Tests
None specified
Railroad Track Work
NDE Tests
None specified
Dredging
A-
9
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
42. TS-02886(August 1980)
Field Test
• load tests on piles
43. NFGS-02891(March 1982)
No tests specified
44. NFGS-02910(November 1982)
Tests
• visual inspection of eachwelded joint
• ultrasonic inspection of
each welded joint• hardness of the weld 6 in. on eachside of joint (Brinell HardnessNumber)
45. TS-03300(June 1980)
Amendment-3 (February 1984)
Field Tests of Concrete
• slump• ball penetration• compressive strength or flexuralstrength (from job site cylinders)
• yield (when challenged by contractingofficer)
• temperature• aggregate sampling and testing forspecified requirements
Wood Marine Piling
NDE Tests
None specified
Pier Timberwork
Welding Crane and Railroad Rail-Thermite Method
NDE Tests
• ultrasonic inspection of eachwelded joints
• hardness of the weld (6 in. oneach side of the joint)
Cast-In-Place Concrete
NDE Tests
None specified
A-10
Guide Spec. No. & Date
Table A. (Continued)
Guide Spec. Title
46. NFGS-03302(April 1981)
Amendment-1 (February 1984)
No tests specified
47. NFGS-03361 Shotcrete(April 1985)
Field Tests NDE Tests
Cast- In-Place Concrete(Minor Building Construction)
None specified• visual inspection• make test panel• compressive and flexural strength
(cores and beams)• durability factor (from core)• air content
48. TS-03410(December 1978)
Testing at Casting Site
• slump• air content• unit weight for lightweight concrete• compressive strength (cylinders made
at casting site, core testing requiredif compressive strength fails to meetrequirements)
Other Requirements NDE Tests
Precast Structural Concrete(Non-Prestressed)
• tolerances of finished products• finished appearance
49. NFGS-03411(August 1981)
Testing at batch plant
• aggregate tests (mechanical analysis,including specific gravity) from samples
• slump• compressive strength (cylinders made at plant)
None specified
Precast Concrete Wall Panels
A-11
Guide Spec. No. & Date
Other Requirements
Table A. (Continued)
Guide Spec. Title
NDE Tests
• tolerances of finished panels and
In Installation• finished appearances
50. TS-03420(December 1978)
Testing at Casting site
• slump• air content• unit weight of lightweight concrete• compressive strength (cylindersmade at casting site)
Other Requirements
• tolerances of finished products• finished appearances• measurement of cracks In
precast-prestressed concrete• camber
51. TS-03501(March 1979)
Field Tests (test specimenstaken at job site)
• compressive strength• oven dry density• coefficient of heat transmission
52. NFGS-04200
(November 1983)
None specified
Precast Prestressed Concrete
NDE Tests
None specified
Insulating Concrete Roof Deck System
NDE Tests
None specified
Unit Masonry
No field tests specified
A-12
Guide Spec. No & Date
53. NPGS-04230(July 1984)
Tests at Job-Site
Table A. (Continued)
Guide Spec. Title
Reinforcing Masonry
• compressive strength of mortarand grout
• compressive strength of masonry prims• efflorescence (masonry units andfor mortar)
54. NPGS-04250(November 1982)
NDE Tests
None specified
[ceramic Glazed Structural ClayFacing Tile] [AND] [PrefacedConcrete Masonry Units]
55. NFGS-05120(August 1981)
Tests
• visual Inspection of welds• test for embrlttlement of welds
56. NFGS-05210(December 1983)
No field tests specified
Structural Steel
NDE Tests
• radiographic• ultrasonic• magnetic particle• dye penetrant
Steel Joists
No tests specified
57. NPGS-05311(May 1983)
Field Tests
• Inspect decking top surface forflatness (straight edge)
58. TS-05321(September 1979)
Field Tests
visual inspection of welds
Steel Roof Decking
NDE Tests
None specified
Steel Floor Deck
NDE Tests
None specified
A-13
Guide Spec. No & Date
59. NFGS-05400(August 1983)
60. TS-05500(November 1980)
Table A. (Continued)
Guide Spec. Title
Cold- Formed Metal Framing
No field tests specified
Metal Fabrications
61
62
No field tests specified
NFGS-07110(April 1983)
Field Tests
sample bulk liquid asphalt(conformance with specificationrequirements)watertightness (cover membranewaterpoofing horizontal surfaces withponded water for 24 hours)
TS-07111(September 1980)
Field Tests
• watertightness of horizontalsurfaces of elastomeric waterproofing(cover with ponded water for 24 hours)
NDE Tests
None specified
63. TS-07120(June 1980)
Field Tests
• prior to application of fluid-appliedwaterproofing, check moisturecontent of substrate using a
moisture meter• check wet film thickness• watertightness, cover waterproofingwith ponded water for 24 hours
Membrane Waterproofing
NDE Tests
None specified
Elastomeric WaterproofingSheet Applied
NDE Tests
None specified
Elastomeric WaterproofingSystem, Fluid Applied
NDE Tests
None specified
A- 14
Table A. (Continued)
Guide Spec. No & Date Guide Spec. Title
64. TS-07130 Bentonite Waterproofing(December 1980)
No field tests specified
65. NFGS-07140 Metallic Oxide Waterproofing(February 1983)
No field tests specified
Guide Spec. No & Date Guide Spec. Title
66. NFGS-07160 Bituminous Dampprooflng(April 1983)
No field tests specified
67. NFGS-07211 Loose Fill (Celluloslc and
(July 1981) Mineral Fiber) Insulation
No field tests specified
68. TS-07220 Roof Insulation(March 1980)
No field tests specified
69. NFGS-07221 Masonry Wall Insulation(November 1982)
No field tests specified
70. NFGS-07222 Tapered Roof Insulation(December 1982)
No field tests specified
71. NFGS-07232 Ceiling, Wall, and Floor
(September 1981) Insulation
No field tests specified
A-15
Guide Spec. No & Date
72. NFGS-07250(February 1984)
Field Tests
73,
• thickness• density
NFGS-07310(August 1983)
Table A. (Continued)
Guide Spec. Title
Sprayed-on Fireproofing
NDE Tests
None specified
Asphalt Shingles
No field tests specified
74. NFGS-07410(May 1983)
Preformed Metal [Roofing] [and]
[Siding]
Factory tests to be conducted by manufacturer
salt sprayformabilityaccelerated weatheringchalking resistancecolor change
Field Tests
None specified
75. NFGS-07511(June 1981)
Field Tests
• abrasion resistance for color coating• humidity test• fire hazard• specular gloss
NDE Tests
None specified
Aggregate Surfaced Bituminous Built-UpRoofing
NDE Tests
• fastener resistance to pullout• watertightness of roofing system
(24 hour ponded water)
76. NFGS-07512(July 1981)
Field Tests
None specified
Smooth Surfaced Bituminous Built-UpRoofing
NDE Tests
• fastener resistance to pullout• watertightness of roofing system
(24 hour ponded water)
None specified
A-16
Table A. (Continued)
Guide Spec. No & Date Guide Spec. Title
77. NFGS-07520 Prepared Roll Roofing(February 1984)
Field Tests NDE Tests
• fastener resistance to pullout None specified
78. NFGS-07540 (August 1979) Silicone Rubber Roof CoatingAmendment- 1 (June 1984)
Pages missing [only pages 1, 1.1, 4, and 8 f guide spec, are given)
79. NFGS-07545 Sprayed Polyurethane Foam (PUF)(July 1984) for Roofing Systems
Field Tests NDE Tests
None specified None specified
80. TS-07600 (September 1978) Flashing and Sheet MetalAmendment-1 (June 1981)
[only Amendment-1 given]
81. NFGS-07920 Sealants and Calkings(August 1981)
No field tests specified
82. NFFGS-08110 Hollow Metal Doors and Frames(November 1981)
No field tests specified
83. NFGS-08120 Aluminum Doors and Frames(February 1984)
No field tests specified
84. NFGS-08129 Aluminum Storm Doors(July 1982)
No field tests specified
A-17
Table A. (Continued)
Guide Spec. No & Date Guide Spec. Title
85. TS-08210 Wood Doors(February 1980)
No field tests specified
86. NFGS-08301 Steel Sliding Hanger Doors(November 1982)
Field Tests NDE Tests
• complete operating test of doors None specified
87. NFGS-08310 Sliding Fire Doors(March 1983)
No field tests specified
88. NFGS-08320 Metal- Clad (Kalamein) Doors and(March 1983) Frames
No field tests specified
89. NFGS-08331 Overhead Coiling Doors(March 1983)
No field tests specified
90. NFGS-08360 Overhead Metal Doors(July 1982)
Field Tests NDE Tests
• demonstrate proper installation, None specifiedand proper functioning of operators,safety features, and controls
91. NFGS-08367 Vertical Uft Metal Doors(July 1982)
No field tests specified
92. NFGS-08371 Aluminum Sliding Glass Doors(July 1983)
No field tests specified
A-18
Table A. (Continued)
Guide Spec. No & Date Guide Spec. Title
93. TS-08510 Steel Windows(January 1980)
Field Tests NDE Tests
• steel windows to comply with None specifiedspecified feeler gage tests
94. NFGS-08520 Aluminum Windows(June 1982)
No field tests specified
95. TS-08525 Storm Windows and Storm Doors(June 1978)
No field tests specified
96. NFGS-08529 Aluminum Storm Windows(July 1982)
No field tests specified
97. TS-08610 Wood Windows
(April 1980)
No field tests specified
98. NFGS-08710 Finish Hardware(March 1985)
No field tests specified
99. NFGS-08800 Glazing(December 1983)
No field tests specified
100. NFGS-09100 Metal Support Systems(February 1984)
No field tests specified
A-19
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
101. NPGS-09110(August 1982)
102. NFGS-09150(April 1981)
103. TS-09215(August 1979)
104. NFGS-09250(March 1985)
105. NFGS-09310(March 1984)
Lathing
No field tests specified
Plastering and Stuccoing
No field tests specified
Veneer Plaster
No field tests specified
Gypsum Board
No field tests specified
Ceramic Tile, Quarry Tile,and Paver Tile
No field tests specified
106. NFGS-09331(October 1983)
Field Tests
• chemical resistance of mortarand grout
• water absorption of mortar• hardness of mortar• before tile is applied test
structural floor for levelnessand uniformity of slope
107. NFGS-09411(September 1983)
Chemical-Resistant QuarryTile Flooring
NDE Tests
None specified
Terrazzo, Bonded to Concrete
No field tests specified
A-20
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
108. NFGS-09561(March 1984)
109. NFGS-09563(July 1982)
110. NFGS-09570(August 1983)
HI. NFGS-09595(July 1983)
112. TS-09661(September 1980)
113. NFGS-09666(February 1982)
Tests
Gymnasium-Type Hardwood StripFlooring Systems
No field tests specified
Portable (Demountable) WoodFlooring
No field tests specified
Wood Parquet Flooring
No field tests specified
Wood Block Industrial Flooring
No field tests specified
Vinyl Composition Tile onConcrete
No field tests specified
Institutional Sheet VinylFlooring
NDE Tests
• stain resistance of flooring material None specified• moisture test for concrete subfloor
114. TS-09670(January 1980)
Field Tests
• None specified
115. NFGS-09682(January 1983)
Field Tests
None specified
Fluid Applied Resilient(Resinous) Flooring
NDE Tests
None specified
Carpet
NDE Tests
None specified
A-21
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
116. NFGS-09690(July 1981)
Field Tests
None specified
117. NPGS-09785(April 1984)
Field Tests
• ground resistance of studs, rods,and interconnecting ground wire
• conductivity of finished floorsurface
• spark resistance of finished floorsurface
Carpet Tile
NDE Tests
None specified
Metallic Type Conductive and SparkResistant Concrete Floor Finish
NDE Tests
None specified
118. TS-09804(January 1978)
119. TS-09805.1(September 1979)
Linseed Oil Protection of ConcreteSurfaces
No field tests specified
Coating Systems ( Coal-Tar for SheetPiling and Other Steel WaterfrontStructures
Field Tests NDE Tests
120.
thickness of coatingsholidays and pin holes in coatingsvisual inspection of coatings
TS-09805.2(May 1980)
• holidays, pin holes and otherdefects/electrical flaw detector
Coating Systems (Vinyl and Epoxy)
for Sheet-Steel Piling and OtherSteel Waterfront Structures
Field Tests NDE Tests
thickness of coatingsholidays, pin holes, and otherdefects in coatingsvisual inspection of coatings
holidays, pin holes and otherdefects/electrical flaw detector
A-22
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
121. NPGS-09815(April 1981)
Field Tests
• dry film thickness/Tooke gage
122. NPGS-09809(September 1981)
Field Tests
• test protective system for holes,voids, cracks, and other damage,visually
123. NPGS-09910(September 1981)
Field Tests
None specified
124. NFGS-09951(August 1982)
Field Tests
• Test walls for moisture contentwith an electric moisture meter
125. TS-10152(April 1980)
Field Tests
None specified
126. NPGS-10162(November 1982)
Field Tests
None specified
High-Build Glaze Coatings
NDE Tests
None specified
Protection of Burled Steel Pipingand Steel Bulkhead Tie Rods
NDE Tests
• test with an electrical flawdetector
Painting of Buildings (Field Painting)
NDE Tests
None specified
Vinyl- Coated Wall Covering
NDE Tests
None specified
Hospital Cubicle Track
NDE Tests
None specified
Toilet Partitions
NDE Tests
None specified
A-23
Guide Spec. No & Date
127. NPGS-10201(January 1983)
Field Tests
None specified
128. NFGS-10270(July 1983)
Field Tests
• floor system electricalresistance
129. NFGS-10440(March 1981)
Field Tests
None specified
130. TS-10623(September 1979)
Field Tests
• Visual tests for light leakage
131. NFGS-10800(October)
Field Tests
None specified
132. TS-11162(November 1980)
Field Tests
• visual inspection of welds• proof-load dockboard• drop tests on dockboard• low temperature environmental
test of loading ramp• visual inspection of dockboard• roll over load test of dockboard
Table A. (Continued)
Guide Spec. Title
Metal [Wall] [And] [Door] Louvers
NDE Tests
None specified
Access Flooring
NDE Tests
None specified
Signs
NDE Tests
None specified
Accordion Folding
NDE Tests
None specified
Toilet and Bath Accessories
NDE Tests
None specified
Fixed Type Industrial Dockboard
NDE Tests
• welds dye penetrant examined• welds magnetic particle tested
A-24
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
133. TS-11171(October 1978)
Field Tests
• hydrostatic pressure of oil
piping systems (using oil)• pneumatical test of gas pipingsystems; soap bubbles to verifytightness of system
• performance test of incineratorincluding controls
• shell temperature (outer shell)of incinerator
134. TS-11301(April 1980)
Field Tests
• hydrostatic test of piping• performance test of separator• test for contaminants in effluent
135. NPGS-11334(August 1982)
Field Tests
• performance test of coimninutor
136. TS-11361.1(September 1980)
Field Tests
• performance test of rectangularclarifier mechanism
137. TS-11361.2(September 1980)
Field Tests
• performance test of circularclarifier mechanism
Incinerators, Packaged, Controlled-Air Type
NDE Tests
None specified (other than pneumatictest)
Packed, Gravity Oil/Water Separator
NDE Tests
None specified
Comminutor
NDE Tests
None specified
Rectangular Clarifier Equipment
NDE Tests
None specified
Circular Clarifier Equipment
NDE Tests
None specified
A-25
Guide Spec. No & Date
138. NFGS-11371(December 1982)
Table A. (Continued)
Guide Spec. Title
Trickling Filter
Field Tests NDE Tests
• performance test of distributormechanism
139. NFGS-11700(April 1984)
Field Tests
performance test of installedequipment
140. NFGS-11701(June 1981)
141. TS-11702(July 1980)
Field Tests
None specified
General Requirements forMedical Equipment
NDE Tests
None specified
Casework, Metal and WoodMedical and Dental
No field tests specified
Medical Equipment , Miscellaneous
NDE Tests
• performance test of equipment
142. NFGS-11704(April 1985)
None specified
[Casework, Movable and Modular forLaboratory and Pharmacies] [And][Materials Handling Units] forMedical Facilities
No field tests specified
143. TS-11720(September 1980)
Field Tests
Stills and Associated Equipment
• performance test of waterdistilling apparatus
NDE Tests
None specified
A-26
Guide Spec. No & Date
144. TS-11722(September 1980)
Field Tests
Table A. (Continued)
Guide Spec. Title
Sterilizers and Associated Equipment
• performance test of equipment
145. TS-11730(September 1980)
Field Tests
• performance test of equipment
146. TS-11744(August 1980)
Field Tests
• performance test of equipment
147. NFGS-11757(August 1981)
Field Tests
• performance test of equipment
148. TS-11770(August 1980)
Field Tests
• insure equipment is
operational
149. NFGS-12322(August 1982)
Field Tests
None specified
150. NFGS-12331(March 1985)
NDE Tests
None specified
Washing Equipment
NDE Tests
None specified
Dental Equipment
NDE Tests
None specified
Radiographic Darkroom Equipment
NDE Tests
None specified
Government-Furnished and ContractorInstalled Existing Medical Equipment
NDE Tests
None specified
Wardrobes
NDE Tests
None specified
Prefabricated Vanities
No field tests specified
A-27
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
151. NFGS-12332(March 1985)
152. TS-12391(January 1981)
153. NFGS-12510(April 1981)
Field Tests
Wardrobe Storage Cabinets
No field tests specified
Kitchen Cabinets [and VanityCabinets]
No field tests specified
Blinds, Venetian (and Audio Visual)
• test for light Intensity
154. NFGS-12540(July 1984)
155. NFGS-12711(February 1984)
156. TS-13092
Field Tests
• Visual inspection
157. NFGS-13121(October 1983)
Field Tests
NDE Tests
None specified
Draperies
No field tests specified
Theater Seating
No field tests specified
X-Ray Shelldlng
NDE Tests
• sample panels tested for con-formance to specified require-ments [salt spray, acceleratedweathering, flexibility,adhesion (film)]
None specified
Pre-englneered Metal BuildingsRigid Frame)
NDE Tests
None specified
A-28
Guld^ Spec. No & Date
Table A. (Continued)
Guide Spec, Title
158. NFGS-13411(June 1981)
Water Storage Tanks
No field tests specified
159. NFGS-13625(February 1982)
Field Tests
• test in-place the flowmeasuring equipment to
demonstrate it meetsthe accuracy requirements
160.. NFGS-13657(March 1983)
Field Tests
• lead-in-air tests(after cleaning)
161. NFGS-13661(August 1981)
Field Tests
• test panels, steel plate,for sand blast for use asstandard of comparison
• air inhibition test (for evidenceof undercure of lining)
• fill test (for leakage of tank)
162. TS-13765(April 1979)
Field Tests
• door sag test• attentuation testing(RF shielded enclosures)
• door static load test
Flow Measuring Equipment (SewageTreatment Plant)
NDE Tests
None specified
Cleaning Petroleum Storage Tanks
NDE Tests
None specified
Fiberglass Reinforced Plastic LiningSystem for Bottotns of Steel Tanks (forPetroleum Fuel Storage)
NDE Tests
• holiday detector test of lining
Radio Frequency Shielded Enclosures,Demountable Type
NDE Tests
• seam leak detector testing(shielding), "sniffer"
A-29
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
163. TS-13766(April 1979)
Field Tests
• swinging door static load test• swinging door sag test• sliding and swinging door closuretest
• attenuation testing• visual Inspection of welds
164. NFGS-13947(August 1983)
Radio Frequency Shielded Enclosures,Welded Type
NDE Tests
seam leak detector testing ofwelds, "sniffer"
Energy Monitoring and Control System(EMCS) Large System Configuration
No field tests specified
165. NFGS-13948(August 1983)
166. NFGS-13950(August 1983)
167. TS-13981.1(March 1980)
Field Tests
Energy Monitoring and Control System(EMCS) Medium System Configuration
No field tests specified
Energy Monitoring and Control System(EMCS) Micro System Configuration
No field tests specified
Solar Energy Systems Flat PlateCollectors (Liquid Type)
• hydrostatic testing• pneumatic testing• start-up and operational tests
NDE Tests
None specified
A-30
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
168. TS-14200(May 1980)
Field Tests
• operational tests• speed load tests• temperature rise tests (motor, etc)• car leveling tests• brake test• insulation (electrical) resistancetests
• buffer tests
169. NFGS-14214(February 1984)
Field Tests
• operational tests• speed load tests• car leveling tests• stop test• pressure test (pump and cylinderhead)
• insulation (electrical) resistancetests
170. NPGS-14304(January 1984)
Field Tests
• grout compressive strength• visual inspection (fittings,bolted joints, welds)
• as-built survey• load test of trackage and curve• throw mechanism operational test
Electric [Passenger] [Freight^Elevator
NDE Tests
None specified
Hydraulic [Passenger] [Freight^Elevator
NDE Tests
None specified
Portal Crane Track Installation
NDE Tests
• ultrasonic inspection of weldedrail joints
A-31
Guide Spec, No & Date
Table A. (Continued)
Guide Spec. Title
171. TS-14305(February 1980)
Field Tests
• operational tests• tolerances (vertical movement)• joint mismatch tolerances (vertical,horizontal)
• joint gap tolerance
172. NFGS-14334(March 1983)
Field Tests
• operational iqspection and tests
173. NFGS-14335(April 1982)
Field Tests
• operational inspection and tests
174. NFGS-14336(January 1982)
Field Tests
• operational inspection and tests
175. NFGS-14637(July 1984)
Field Tests
• operational inspection andtests
176. NFGS-15011(February 1981)
Fabricated Portal Crane TrackSwitches and Frogs
NDE Tests
None specified
Monorails with Manual Hoist
NDE Tests
None specified
Monorails with Air Motor PoweredHoist
NDE Tests
None specified
Cranes, Overhead Electric,Overrunning Type
NDE Tests
None specified
Cranes, Overhead Electric, Underrunning(Under 20,000 pounds)
NDE Tests
None specified
Mechanical General Requirements
No field tests specified
A-32
Guide Spec, No & Date
Table A. (Continued)
Guide Spec. Title
177. NFGS-15116(July 1982)
Field Tests
• Visual Inspection of welds
178. TS-15200(September 1979)
Field Tests
• check for vibration and noisetransmission through connections,piping duct work, foundations,and walls
• vibration tests for conformancewith criteria
• sound level tests for conformancewith criteria
179. NFGS-15251(January 1984)
Field Tests
None specified
180. TS-15301(December 1978)
Field Tests
Welding Pressure Piping
NDE Tests
NDE personnel shall be certifiedas qualifiedradiographic examination of weldsliquid penetrant examination of weldsmagnetic particle examination of weldsultrasonic examination of welds
Noise, Vibration, and [Seismic]Control
NDE Tests
None specified
• leakage tests• alignment of pipeline
Insulation for Exterior PipedUtilities
NDE Tests
None specified
Exterior Sanitary Sewer and DrainageSystem Piping
NDE Tests
None specified
A-33
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
181. TS-15355(October 1980)
Field Tests
• metal welding or brazing inspection• PE Fusion welding inspection• pressure test piping system• operational tests for conformancewith criteria
182. NFGS-15361(January 1984)
Field Tests
• acceptance tests• pneumatic test (leakage)
183. NFGS-15362(January 1984)
Field Tests
• pneumatic test (leakage)• acceptance tests (conformancewith specified requirements)
184. NFGS-15365(February 1984)
Field Tests
• pneumatic test (leakage of system)• acceptance and opeational tests of
system
185. TS-15388(October 1973)
186. TS-15390(May 1972)
Fuel Gas Piping
NDE Tests
None specified
Carbon Dioxide Fire ExtinguishingSystems (High Pressure)
NDE Tests
None specified
Carbon Dioxide Fire ExtinguishingSystems (Low Pressure)
NDE Tests
None specified
Halon 1301 Fire ExtinguishingSystem
NDE Tests
None specified
Screening Equipment (Sewage)
No field tests specified
Aeration Equipment ( Sewage
)
No field tests specified
A-34
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
187. TS-15395(October 1973)
188. TS-15399(March 1979)
Field Tests
Sludge Digestion Equipment
No field tests specified
Package Rotating Biological Con-tractor Wastewater Treatment Unit
• cathodlc protection Inspection• pressure test each pipeline• acceptance and operational tests ofsystem for conformance to specifiedrequirements
NDE Tests
None specified
189. NFGS-15400 Amendment-1(September 1983)
Plumbing
190. NFGS-15403(March 1981)
Field Tests
No field tests specified
Nonflammable Medical Gas Systems
• leak tests of systems• equipment pressure tests of joints• vacuum tests
191. NFGS-15411(July 1983)
Field Tests
NDE Tests
None specified
• visual Inspection of welds• destructive tests of welds• hydrostatic and leak tightnesstests of system
• operational tests
Compressed Air Systems (Non-Breathing Air Type)
NDE Tests
• NDE personnel shall be certified• radiographic (for welds)• liquid penetrant (for welds)• magnetic particle (for welds)
A-35
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
192. NFGS-15460(July 1984)
Field Tests
• operational and acceptance tests
193. TS-15502(October 1980)
Field Tests
• hydrostatic pressure test of system• acceptance and operational tests
194. NFGS-15540(February 1982)
Field Tests
• hydrostatic pressure tests• acceptance and operational tests
195. TS-15609(April 1978)
Field Tests
hydrostatic pressure tests ofpiping systemsacceptance and operational tests
196. NFGS-15612(April 1984)
Field Tests
• visual inspection of welds• piping strength and tightness(pressure test)
Hospital Plumbing Fixtures
NDE Tests
None specified
Fire Extinguishing SprinklerSystems (Dry Pipe)
NDE Tests
None specified
Fire Pumps
NDE Tests
None specified
Aviation Fuel Distribution Systems
NDE Tests
None specified
Gas Distribution System
NDE Tests
• electrical holiday detector fordiscontinuities in pipe coatings
A-36
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
197. NPX;S-15631
(September 1981)
Field Tests
• acceptance and operational testsfor compliance with contractrequirements
• strength and tightness (hydrostatic test)• pneumatic tests (air casing and ducts)• combustion tests• capacity and efficiency tests
198. NFGS-15632(September 1981)
Field Tests
• acceptance and operational testsfor compliance with contract requirements
• strength and tightness (hydrostatic test)• pneumatic tests (air casing and ducts)• combustion tests• capacity and efficiency tests• steam tests
Steam Boilers and Equipment500,000 - 18,000,000 Btu/h)
NDE Tests
None specified
Steam Boilers and Equipment18,000,000 - 60,000,000 Btu/HrInput)
NDE Tests
None specified
199. NFGS-15651(January 1983)
Field Tests
Refrigerant, Chilled Water,Condenser Water, Hot and ColdWater (Dual Service) Piping
NDE Tests
• tightness of system• pressure test (refrigerant system)• operational tests
200. TS-15652Amendment-
1
(July 1982)
None specified
Central Refrigeration System forAir Conditioning
No field tests specified
A-37
Guide Spec. No & Date
201. NFGS-15653(June 1984)
Field Tests
• operational tests• sound tests
202. NFGS-15707(September 1981)
Field Tests
• hydrostatic pressure test of
system• operational test• moisture-density test of backfill• In-place compaction test
203. NFGS-15711(March 1981)
Field Tests
Table A. (Continued)
Guide Spec. Title
Unitary Air Conditioning Systems
NDE Tests
• leak testing (electronic typedetectors)
[Factory Insulated] Glass FiberReinforced Plastic (FRF) PipeCoondensate Return System
NDE Tests
None specified
• strength and tightness(hydrostatic test) forboiler and piping system
• combustion test• operational test• capacity and efficiency test
204. NFGS-15721(March 1981)
Field Tests
• hydrostatic pressure test ofpiping system
• operational test
205. TS-15802(November 1972)
Hot Water Heating System
NDE Tests
None specified
Steam System and Terminal Units
NDE Tests
None specified
Air Supply Systems
Note: The last part of this specification was missing
A-38
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
206. TS-15813(October 1980)
Field Tests
• operational test• fire test• duct test
207. TS-15820(September 1980)
Field Tests
• operational test
208. TS-15822(October 1980)
Field Tests
• operational test
209. NFGS-15840(November 1982)
Field Tests
• operational test• pressure tests for air leakage
(ducts, plenums, and casings)
210. TS-15852.2(May 1980)
Field Tests
• operational test
211. NFX;S-15852.3(January 1983)
Field Tests
• operational test
Warm Air Heating Systems
NDE Tests
None specified
Air Handling and Distribution Equipment
NDE Tests
None specified
Evaporative Cooling System
NDE Tests
None specified
Ductwork and Accessories
NDE Tests
None specified
Duct Collector, Electrostatic PrecipitationType (Flue Gas Particulates)
NDE Tests
None specified
Duct Collector, Fabric Filter Type(Fly Ash Particles in Flue Gas)
NDE Tests
None specified
A-39
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
212. TS-15901(August 1980)
Field Tests
• operational test
213. TS-16011(November 1978)
Space Temperature Control Systems
NDE Tests
None specified
General Requirements, Electrical
214. NFGS-16113(February 1984)
Field Tests
No field tests specified
Underfloor Raceway System
• electrical continuity test
215. NFGS-16202(October 1981)
Field Tests
• hydrostatic test of piping• operational tests and acceptancetests
216. NFGS-16203(October 1981)
Field Tests
• hydrostatic test of piping• electrical Insulation resistancetests
• operational and acceptance tests
NDE Tests
None specified
Power Generating Plants, Diesel Electric(Design 1) 500 to 2500 kW Continuous DutyUnits
NDE Tests
None specified
Power Generating Plants, Diesel Electric(Design 2) 2,501 kW and Larger ContinuousDuty Units
NDE Tests
None specified
A-40
Guide Spec, No & Date
Table A. (Continued)
Guide Spec. Title
217. NFGS-16204(November 1981)
Power Generating Plants, Diesel Electric(Design 3) 300 to 1,000 kW Standby DutyUnits
Field Tests
• hydrostatic test of piping• electrical Insulation resistancetests
• operational and acceptance tests
218. NFGS-16205(September 1981)
Field Tests
• hydrostatic test of piping• electrical Insulation resistancetests
• operational and acceptance tests
219. NFGS-16207(November 1981)
Field Tests
• hydrostatic test of piping• electrical Insulation resistancetests
• operational and acceptance tests
220. NFGS-16208(July 1982)
Field Tests
• operational test
221. TS-16262(November 1982)
NDE Tests
None specified
Power Generating Plants, Diesel Electric(Design 4) 1,001 kW and Larger StandbyDuty Units
NDE Tests
None specified
Power Generating Plants, Diesel Electric(Design 6) 1,001 kW and Larger EmergencyDuty Units
NDE Tests
None specified
Diesel Engine-Generator Set(25-250 kW
NDE Tests
None specified
Automatic Transfer Switches
No field tests specified
A-41
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
222. NFGS-16301(April 1984)
Field Tests
• test 600 volt conductors for
short circuits or accidental grounds• test high voltage cables• test ground rods for ground resistancevalue
Underground Electrical Work
NDE Tests
None specified
223. NFGS-16302(February 1984)
Field Tests
• test ground rods for groundresistance value
• operational test• test transformer secondary voltages
224. NFGS-16304Amendment -1
(July 1982)
No field tests specified
225. NFGS-16335(September 1981)
Field Tests
Overhead Electrical Work
NDE Tests
None specified
Pier, Electrical Distributionfor Naval Stations
Transformers, Substations andSwltchgear, Exterior
NDE Tests
• acceptance tests• test transformer secondary voltages• dielectric tests (low voltageswltchgear)
226. NFGS-16402(February 1983)
Field Tests
None specified
• operational and acceptance tests• test 600-volt wiring (no short circuitsor accldential grounds)
• grounding system test
A-42
Ulterior Wiring Systems
NDE Tests
None specified
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
227. TS-16475(August 1979)
Field Tests
• operational and acceptance tests• ground resistance tests
Interior Transformers
NDE Tests
None specified
228. NFGS-16462(July 1981)
Field Tests
• operational and acceptance tests• ground resistance of ground rods
229. NPGS-16465(March 1983)
Field Tests
• operational and acceptance tests• relay testing• transformer tests• field dielectric tests• ground resistance tests
230. TS-16475(August 1979)
Field Tests
• operational and acceptance tests• ground resistance tests
231. NFGS-16492(January 1983)
Field Tests
Pad Mounted Transformers
NDE Tests
None specified
Interior Substations
NDE Tests
None specified
• operational and acceptance tests• voltage and frequency transiet tests• ground resistance tests
Interior Switchgear
NDE Tests
None specified
Motor-Generator Sets, 400 Hertz
NDE Tests
None specified
A-43
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
232. NPGS-16530(March 1985)
Field Tests
• operational tests• insulation resistance test• ground resistance tests
233. NFGS-16560(June 1982)
Pield Tests
• operational tests• electromagnetic interference• test 600-volt class conductors
(no short circuits or accidentalgrounds)
• counterpoise and ground rod tests• progress testing for series airfieldlighting circuits
• electrical acceptance tests for seriesand multiple airfield lightingcircuits
• low voltage continuity, ground, andinsulation resistance tests
• high voltage insulation resistance test• electric tests
234. TS-16641(March 1979)
field Tests
• static pull test of anode withlead wires
• operational test
Exterior Lighting
NDE Tests
None specified
Airfield Ughting
NDE Tests
None specified
Cathodic Protection by GalvanicAnodes
NDE Test
None specified
A-44
Guide Spec. No & Date
Table A. (Continued)
Guide Spec, Title
235. TS-16642(March 1979)
Field Tests
• static pull test of anode withlead wires
• wire for power service (free fromshort circuits and grounds)
• operational test
Cathodlc Protection by ImpressedCurrent
NDE Tests
None specified
236. NFGS-16650(June 1983)
field Tests
• operational and acceptance tests
237. NPGS-16721(December 1972)
Field Tests
• ground resistance• dielectric strength and Insulationresistance
• operational tests ( power supply, alarm,box and transmitter, signaltransmission and recording, trouble lineoperation, manual-set transmittertest)
238. TS-16722(October 1978)
Field Tests
• operational and functional tests• ground resistance• dielectric strength and insulationresistance
Radio Frequency InterferencePower Line Filters
NDE Tests
None specified
Exterior Fire Alarm System
NDE Tests
None specified
Fire Alarm and Fire DetectingSystem (Local)
NDE Tests
None specified
A-45
Guide Spec. No & Date
Table A. (Continued)
Guide Spec. Title
239. NFGS-16723(October 1981)
Field Tests
• acceptance test• ground resistance
Fire Alarm System Radio Type
NDE Tests
None specified
A-46
APPENDIX B. REVIEWED NAVY GUIDE SPECIFICATIONS HAVING NDE TESTS
The Navy Guide Specifications that contain required NDE tests are listed in
Table B along with the corresponding NDE tests. Of the 239 Guide Specifications
reviewed (see Appendix A), 29 contained required NDE tests. Some of the tests
included under NDE tests in Table B were listed as field tests in the
specifications. Those tests listed as field tests in the specifications are
denoted with a footnote.
B-1
Table B. Reviewed Navy Guide Specifications that Contain Required NDE Tests
Guide Spec. No & Date
NFGS-02452(September 1984)
NFGS-02854(March 1983)
NFGS-02910(November 1982)
NFGS-05120(August 1981)
NFGS-07110(April 1983)
TS-0711(September 1980)
TS-07120(June 1980)
NFGS-07511(June 1981)
NFGS-07512(July 1981)
NFGS-09666(February 1982)
Guide Spec. Title
Railroad Trackwork
Railroad Track Work
Welding Crane and RailroadRail - Thermite Method
Structural Steel(some papers weremissing from this spec.)
Membrane Waterproofing
NDE Tests
• Ultrasonic inspectionof welded rail joints
• Ultrasonic inspectionrail joints (MIL-STD-1699)
• Ultrasonic inspection ofeach welded joint
• Hardness of the weld(6 in. on each side of
the joint)
• Nondestructive evaluationof welds
*• Watertightness (pondedwater for 24 hours)
Elastomeric Waterproofing *• Watertightness (pondedSheet Applied water for 24 hours)
Elastomeric Waterproofing *• Prior to waterproofingSystem, Fluid Applied
Aggregate SurfacedBituminous Built-UpRoofing
Smooth SurfacedBituminous Built-UpRoofing
Institutional SheetVinyl Flooring
application, checkmoisture content ofsubstrate using a
moisture meter
*• Watertightness (pondedwater for 24 hours)
*• Watertightness (pondedwater for 24 hours)
Watertightness (pondedwater for 24 hours)
Moisture test forconcrete subfloor
* Listed as field tests in specifications.
B-2
Guide Spec. No & Date
NFGS-09785(April 1984)
Table B. (Continued)
Guide Spec. Title
Metallic Type Conductive *
and Spark Resistant ConcreteFloor Finish
NDE Tests
Ground resistanceof studs, rods, andinterconnecting groundwire
TS-09805.1(September 1979)
TS-09805.2(May 1980)
NFGS-09815(April 1981)
NFGS-09809(September 1981)
NFGS-09951(August 1982)
NPGS-10270(July 1983)
*•
Coating Systems (Coal-Tar) *
for Sheet Piling and OtherSteel Waterfront Structures
Coating Systems (Vinyl and *•
Epoxy) for Sheet-Steel Pilingand Other Steel WaterfrontStructures
High-Build Glaze Coatings
Protection of Buried Steel *
Piping and Steel BulkheadTie Rods
Vinyl-Coated Wall Covering
Access Flooring
Conductivity of
finished floor surface
Spark resistance offinished floor surface
Thickness of coatings
Holidays, pin holesand other defects/electrical flawdetector
Thickness of coating
Holidays, pin holesand other defects/electrical flawdetector
Dry film thickness/Tooke Gage
Visual inspection ofprotective systems for
holes, voids, cracks,and damage
Test with an electricalflaw detector
Test walls for moisturecontent/eletric moisturemeter
Floor system electricalresistance
* Listed as field tests in specification.
B-3
Guide Spec. No & Date
TS-11162(November 1980)
TS-11171(October 1978)
TS-11301(April 1980)
NFGS- 13661(August 1981)
TS-13765(April 1979)
TS-13766(April 1979)
NFGS-1A304(January 1984)
Table B. (Continued)
Guide Spec. Title
Fixed Type IndustrialDockboard
Incinerators , Packaged
,
Controlled-Air Type
Packaged, Gravity Oil/
Water Separator
Fiberglass ReinforcedPlastic Lining System forBottoms of Steel Tanks(for Petroleum Fuel Storage)
Radio Frequency Shielded
Enclosures , DemountableTZ£e
Radio Frequency ShieldedEnclosures, Welded Type
Portal Crane TrackInstallation
NDE Tests
*• Visual inspection ofdockboard and welds
*• Proof-load dockboard
• Welds, dye penetrantexamined
• Welds, magnetic patricletested
• Pneumatical test ofgas piping systems;soap bubbles to verifytightness of system
*• Hydrostatic pressureof oil piping systems(using oil)
• Hydrostatic test ofpiping
• Holiday detector testof lining
Seam leak detectortesting (shielding),"sniffer"
Seam leak detectortesting of welds,"sniffer"
Ultrasonic inspectionof welded rail joints
* Listed as field test in specification.
B-4
Guide Spec. No & Date
NFGS-15116(July 1982)
NFGS-15403(March 1981)
NFGS-15411(July 1983)
NFGS-15612(April 1984)
NFGS-15653(June 1984)
Table B. (Continued)
Guide Spec. Title
Welding Pressure Piping
Nonflammable MedicalGas Systems
Compressed Air Systems(Non-Breathing Air Type )
Gas Distribution System
Unitary Air ConditioningSystems
NDE Tests
*• Visual inspection ofwelds
• NDE personnel shall becertified as qualified-radiographic, liquidpenetrant, magneticparticle, ultrasonic-examination of weldsconform to "ASME Boilerand Pressure Vessel Code,Section V."
*• Leak tests ofsystems
*• Visual inspectionof welds
• NDE personnel shall becertified-radiographic
,
liquid penetrant,magnetic particle-forwelds
*• Visual inspection of
welds• Electrical holidaydetector for discon-tinuities in pipecoatings
• Leak testing (electronictype leak detector)
* Listed as field test in specification
B-5
APPENDIX C. LISTS OF REVIEWED NCEL TECHDATA SHEETS AND NCEL TECHNICAL ANDRESEARCH REPORTS THAT CONTAIN NDE METHODS
The Navy publications provided by NCEL and NAVFAC which were reviewed are
listed in this appendix. Section 2.4 provides information about these types
of reports. Table Cl contains a list of reviewed NCEL Techdata Sheets and
Table C2 contains a list of reviewed NCEL technical and research reports.
C-1
Table CI. List of Reviewed NCEL Techdata Sheets that Contain NDE Methods
NCEL Techdata Sheet 79-09, "Inspection of Painting," Port Hueneme , CA,
September 1979.
NCEL Techdata 75-31, "Measuring Water Permeability of Masonry Walls,"Port Hueneme, CA, December 1985.
NCEL Techdata Sheet 82-13, "Leak Detection in Pipelines," Port Hueneme, CA,
September 1982.
NCEL Techdata Sheet 84-05, "Infrared Thermometers for Roofing Inspectors,"Port Hueneme, Ca, March 1984.
NCEL Techdata Sheet 77-20, "Use of Windsor Probe Test System for StrengthEvaluation of Concrete in Naval Construction," Port Hueneme, CA, December 1977
NCEL Techdata Sheet 80-12, "Problems with Underwater Ultrasonic Inspection,"Port Hueneme, CA, October 1980.
NCEl Techdata Sheet 76-13, Inspection Methods for Wood Fender and BearingPiles," Port Hueneme, CA, September 1976.
NCEL Techdata Sheet 82-14, "Locating and Tracing Buried Metallic Pipelines,"Port Hueneme, CA, September 1982.
C-2
Table C2 . List of Reviewed NCEL Technical and Research Reports that ContainNDE Methods
NCEL Technical Memorandum M-43-81-07, "An Evaluation of Pulse Echo UltrasonicTechniques for Underwater Inspection of Steel Waterfront Structures,"R. L. Bracket t and L. W. Tucker, Port Hueneme , CA, May 1981.
NCEL Technical Memorandum M-43-81-08, "Ultrasonic Inspection of WoodenWaterfront Structures," C. A. Keeney, Port Hueneme, CA, May 1981.
NCEL Technical Memorandum M-51-81-11, "Concepts for Detecting Weak Spotsin Pavement-Encased Trackage on Waterfront Facilities," G. E. Warren,Port Hueneme, CA, August 1981.
NCEL Technical Note N-1594, "Nondestructive Test Equipment for Wire Rope,"H. H. Haynes and L. D. Underbakke, Port Hueneme, CA, October 1980.
NCEL Technical Memorandum M-52-80-10, "Specialized Roof Moisture Inspection,"Robert L. Alumbaugh and John R. Keeton, Port Hueneme, CA, September 1980.
NCEL Technical Memorandum M-52-81-06, "Inspection of POL Supply Facilities,"Thorndyke Roe, Jr., Port Hueneme, CA, September 1981.
NCEL Technical Memorandum M-55-81-04, "Inspection of Underground UtilityLines-Milestone Zero Report," S. S. Wang, Port Hueneme, CA, July 1981,
NCEL Technical Memorandum M-55-81-06, "Inspection of Underground UtilityLines," S. S. Wang and S. J. Oppedisano, Port Hueneme, CA, November 1981,
NCEL Technical Memorandum M-43-78-09, "Underwater Inspection and NondestructiveTesting of Waterfront Structures: A State of the Art Assessment,"R. L. Brackett, Port Hueneme, CA, June 1978.
NCEL Technical Memorandum M-51-80-27, "Noncontact Displacement Measurementas an Inspection Tool for Naval Shipyard Trackage," G. E. Warren, PortHueneme, CA, December 1980.
NCEL Technical Memorandum M-52-77-3, "Roofing Survey of Naval Shore Bases,"J, R. Keeton and R. L, Alumbaugh, Port Hueneme, CA, March 1977.
NCEL Technical Note N-1624, "Underwater Inspection of Waterfront Facilities:Inspection Requirements Analysis and Nondestructive Testing TechniqueAssessment," R. L. Brackett, W. J. Nordell, and R. D, Rail, Port Hueneme, CA,
March 1982.
NCEL Technical Note N-1632, "Evaluation of NDT Equipment for SpecializedInspection," G. Warren, Port Hueneme, CA, June 1982.
NCEL Technical Report R-903, "Pulse Echo Ultrasonic Techniques for UnderwaterInspection of Steel Waterfront Structure," R. L. Brackett, L. W. Tucker, and
R. Erich, Port Hueneme, CA, June 1983.
C-3
Table C2. (Continued)
NCEL Technical Note N-1233, "Calibration of Windsor Probe Test System forEvaluation of Concrete in Naval Structures," J, R. Keeton and V. Hernandez,Port Hueneme, CA, June 1972.
NCEL Technical Note N-1703, "Evaluation of Nondestructive Underwater TimberInspection Techniques," C. A. Keeney and S. E. Pollio, Port Hueneme, CA,
August 1984.
NCEL Technical Memorandum M-43-84-01, "Evaluation and Comparison of
Commerical Ultransonic and Visual Inspections of Timber Piles," A. P. Smith,Port Hueneme, CA, December 1983.
Technical Memorandum M-53-85-03, "Detection of Underground Utilities andObstacles with Ground Penetration Radars - An Initiation Decision Report,"M. C. Hironaka and G. D. Cline, Port Hueneme, CA, January 1985.
Technical Memorandum M-53-82-02, "Dectection of Underground Utilities andObstacles - An Initiation Decision Report," M. C. Hironaka, Port Hueneme,CA, September 1982 .
Technical Memorandum M-53-84-5, "Ground Probing Radars and Hand-Held Detectorsfor Locating Underground Utility Lines and Other Objects," M. C. Hironaka andG. D. Cline, Port Hueneme, Ca, August 1984.
NCEL Technical Memorandum M-43-81-07, "An Evaluation of Pulse Echo UltrasonicTechniques for Underwater Inspection of Steel Waterfront Structures,"R. L. Bracket t and L. W. Tucker, Port Hueneme, CA, May 1981.
NCEL Technical Memorandum M-43-78-09 , "Underwater Inspection and NondestructiveTesting of Waterfront Structures: A State-of-the-Art Assessment Report,"R. L. Brackett, Port Hueneme, CA, February 1984.
NCEL Technical Memorandum tm no: 52-84-04, "Design and Development of a
Portable Infrared Spectrophotometer for NDT Analysis of Coatings,"T. Novinson, Port Hueneme, CA, November 1983.
NCEL Technical Memorandum tm no: 52-83-03, "Laboratory Prototype of a
Portable Infrared Spectrophotometer for NDT Field Analysis of Coatings andOther Organic Materials," T. Novinson and D. S. Kyser, Port Hueneme, CA,
November 1982.
NCEL Technical Note N-1179, "Measuring Water Permeability of MasonryWalls," H. Hochmam, Port Hueneme, CA, August 1971.
NCEL Technical Memorandum M-55-82-01 , "Leak Detection in UndergroundUtility Lines-Status Report," S. S. Wang and S. J. Oppendisano, PortHueneme, CA, May 1982.
C-4
APPENDIX D. ASTM STANDARDS FOR NDE METHODS FOR CONSTRUCTION MATERIALS ANDBUILDING COMPONENTS
ASTM has recognized the need for standards covering nondestructive evaluation
methods for a variety of materials and applications. Consequently, a number
of ASTM standards for NDE procedures have been issued. ASTM standards for
NDE methods for concrete are listed in Table Dl . Some ASTM standards for other
common NDE methods are listed in Table D2. As new ASTM standards for NDE appear,
they can be located by reviewing the index to ASTM standards which is published
annually.
D-1
Table Dl . ASTM Standards for NDE Methods for Concrete
NDE Method ASTM Standard and Designation
Rebound Hammer Test for rebound number of hardenedconcrete: C 805
Penetration Probe Test for penetration resistance ofhardened concrete : C 803
Ultrasonic Pulse Velocity Test for pulse velocity throughconcrete: C 597
Nuclear Moisture Meter
Cast-in-place Pullout
Test for moisture content of soil andsoil-aggregate in place by nuclearmethods (shallow depth): D 3017
Test for pullout strength of hardenedconcrete: C 900
Visual Practice for examination of hardenedconcrete in constructions: C 823
Corrosion of Rebars
Mechanical Properties
Test for half cell potentials ofreinforcing steel in concrete: C 876
Test for fundamental transverse,longitudinal, and torsional frequenciesof concrete specimens: C 215
(laboratory method)
D-2
Table D2 . ASTM Standards for NDE Methods for Construction Materials andBuilding Components
NDE Method
Acoustic Emission
ASTM Standard and Designation
Practice for acoustic emission monitoringduring continuous welding: E 749
Practice for acoustic emission monitoringof structures during controlled stimulation:E 569
Practice for acoustic emissionexamination of reinforced thermosettingresin pipe: E 1118
Air Leakage Method for Determining Air Leakage Rateby Tracer Dilution: E 741
Method for Determining Air Leakage Rateby Fan Pressurizatlon: E 779
Coating Thickness Testing Practice for measuring coating thicknessby magnetic-field or eddy-current(electromagnetic) test methods: E 376
Measurement of thickness of anodic coatingson aluminum and of other nonconductivecoatings on non-magnetic basis metals witheddy-current instruments: B 244
Measurement of dry film thickness of
nonmagnetic coatings applied to a ferrousbase: D 1186
Measurement of dry film thickness of
nonconductive coatings applied to a
nonferrous metal base: D 1400
Measurement of film thickness of pipelinecoatings on steel: G 12
Measurement of dry film thickness ofprotective coating systems by destructivemeans: D 4138 (Tooke gage)
Practice for measurement of wet filmthickness by notch gages: D 4414
Measurement of wet film thickness of
organic coatings: D 1212
D-3
Table D2 (Continued)
NDE Method
Eddy Current Method
ASTM Standard and Description
Test for electrical conductivity byuse of eddy current : B 342
Practice for In situ electromagnetic(eddy-current) examination ofnonmagnetic heat exchanger tubes:E 690
Practice for electromagnetic (eddy-current)testing of seamless copper and copperalloy tubes: E 243
Hardness Testing Hardness conversion tables for metals(relationship between Brlnell hardness,Vlckers hardness, Rockwell hardness,Rockwell superficial hardness, andKnoop hardness) : E 140
Test for Brlnell hardness of metallicmaterials: E 10
Test for Vlckers hardness of metallicmaterials: E 92
Test for Indentation hardness of metallicmaterials by portable hardness testers:E 110
Rapid indentation hardness testing of
metallic materials: E 103
Test for Rockwell hardness and Rockwellsuperficial hardness of metallicmaterials: E 18
Test for film hardness by pencil test:D 3363
Magnetic Particle Practice for magnetic particleexamination: E 709
Specification for magnetic particleInspection of large crankshaftforglngs : A 456
D-4
Table D2 (Continued)
NDE Method
Magnetic Particle(Continued)
ASTM Standard and Description
Reference photographs for magneticparticle indications on castings: E 125
Method for magnetic particle examinationof steel forgings : A 275
Terminology of symbols and definitionsrelating to magnetic testing: A 340
Penetrant Testing Practice for liquid penetrant inspectionmethod: E 165
Reference photographs for liquidpenetrant inspection: 433
Radiographic Testing Reference radiographs for steel coatingsup to 2 in. (51 mm) in thickness: E 446
Reference radiographs for heavy-walled(2 to 4-1/2 inch) steel castings: E 186
Reference radiographs for steel fusionwelds: E 390
Method for controlling quality of
radiographic testing: E 142
Practice for radiographic testing: E 94
Soils Inspection Method for density of soil in place by
the sand-cone method: D 1556
Methods for density of soil and soil-
aggregate in place by nuclear methods(shallow depth): D 2922
Methods for moisture-density relationsof soils and soil-aggregate mixtures,
using 5.5-lb (2.49 kg) rammer and
12-in. (305 mm) drop: D 698
Method for penetration test and
split-barrel sampling of soils: D 1586
D-5
Table D2 (Continued)
NDE Method
Soil Inspection(Continued)
ASTM Standard and Description
Classification of soils for engineeringpurposes: D 2487
Method for deep, quasi-static cone andfriction-cone penetration tests ofsoil: D 3441
Ultrasonic Testing Practice for measuring thickness bymanual ultrasonic pulse-echo contactmethod: E 797
Practice for ultrasonic pulse-echostraight-beam testing by the contactmethod: E 114
Practice for ultrasonic contactexamination of weldments : E 164
Practice for ultrasonic examination of
heavy steel forgings : A 388
Straight-beam ultrasonic examinationof steel plates: A 435
Practice for ultrasonic inspection of
metal pipe and tubing: E 213
Practice for measuring ultrasonicvelocity in materials: E 494
Testing for leaks using ultrasonics: E 1002
Practice for ultrasonic examination of
longitudinal welded pipe and tubing: E 273
Uplift Testing Field testing uplift resistance of roofingsystems employing steel deck rigidinsulation and bituminous built-up roofing;
E 907
Window Testing Method for strucutural performance ofglass in windows, curtain walls, and
doors under the influence of uniformstatic loads by nondestructivemethod: E 998
D-6
FORM NBS-1 MA (REV, n -84)
U.S. DEPT. OF COMM.
BIBLIOGRAPHIC DATASHEET (See /n struct/on s)
I. PUBLICATION ORREPORT NO.
NBS/TN-1247
2. Performing Organ. Report No. 3. Publication Date
June 1987
4. TITLE AND SUBTITLE
Review of Nondestructive Evaluation Methods Applicable to Construction Materials
and Structures
5. AUTHOR(S)
Robert G. Mathey and James R. Clifton
6. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions)
NATIONAL BUREAU OF STANDARDSU.S. DEPARTMENT OF COMMERCEGAITHERSBURG, MD 20899
7. Contract/Grant No.
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Final
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Naval Civil Engineering Laboratory
Port Hueneme, CA 93043-5003
10. SUPPLEMENTARY NOTES
[^21 Document describes a computer program; SF-185, FlPS Software Summary, is attached.
11. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a si gnificantbibliography or literature survey, mention it here)
Nondestructive evaluation (NDE) methods for evaluating in situ construction
materials and for condition assessment of building components and systems were identi-
fied and are described. This report is intended to help inspectors and those involved
in condition assessment choose appropriate NDE methods for specific building materials,
components, and systems. Important properties of building materials along with
important performance requirements for building components are listed, and appropriate
NDE methods lot determining these properties are recommended. In many cases the
advantages and limitations of the NDE methods are presented. Potential NDE methods
which may or may not require further research and development before they are ready
for routine use were also identified and are briefly described. In addition, ASTM
standards for NDE methods for concrete and other building materials and components were
identified.
In a related aspect of the study, current Navy practices relative to the use of NDE
methods in the construction and service cycle of buildings and other structures were
reviewed. This review was based on Navy reports and documents provided by NCEL and
NAVFAC, and on discussions with NAVFAC personnel involved with buildings and
structures problems where NDE methods are used for diagnostic purposes. Navy Guide
Specifications were examined for required tests, both NDE and destructive, of in situ
building materials and components
12. KEY WORDS (S/x to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)
building components; building diagnostics; building materials; condition assessment;
construction materials; in situ evaluation; nondestructive evaluation
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