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SHRP2: EDUCATION CONNECTIONINTRODUCTION TO INFRASTURCTURE

Prepared By:Ayman W. Ali, Ph.D.Presented By:Yusuf Mehta, Ph.D., P.E.

Prepared as a part ofSHRP2 Education Connection:Incorporating SHRP2 Solutions into Academia

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Presentation Outlineq Introduction to SHRP2 Solutionsq Module SHRP R23q Module SHRP R06Aq Module SHRP R19q Questions

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Introduction to SHPR2 Solutions

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What is SHPR2?

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Save lives. Save money. Save time.

q Products developed from objective, credible research

q Solutions that respond to transportation community challenges – safety, aging infrastructure, congestion

q Tested products, refined in the field

Importance of SHPR2

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Tools for the Road AheadSHRP2 Solutions have the power to change the way transportation agencies do business. SHRP2:

Provides new research-based tools and innovative products and processes

Creates efficiencies

Uses State and Federal taxpayer investment more effectively

SHPR2 is a Partnership

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Collaborative Effort of FHWA, AASHTO, and TRBq National partnership to address critical transportation

challenges:

q Making highways saferq Repairing deteriorating infrastructureq Reducing congestion

q Aims to advance innovative ways to plan, renew, operate, and improve safety on the Nation's highways

SHPR2 Focus Areas

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Safety: fostering safer driving through analysis of driver, roadway, and vehicle factors in crashes, near crashes, and ordinary driving

Renewal: rapid maintenance and repair of deteriorating infrastructure using already-available resources, innovations, and technologies

Reliability: reducing congestion and creating more predictable travel times through better operations

Capacity: planning and designing a highway system that offers minimum disruption and meets the environmental and economic needs of the community

Renewal Products

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PavementsGuidelines for the Preservation of High-Traffic-Volume Roadways (R26)Precast Concrete Pavement (R05)New Composite Pavement Systems (R21)Pavement Renewal Solutions (R23) Technologies to Enhance Quality Control on Asphalt Pavements (R06C)Tools to Improve PCC Pavement Smoothness During Construction (R06E)

Project DeliveryManaging Risk in Rapid Renewal Projects (R09)Project Management Strategies for Complex Projects (R10)Performance Specifications for Rapid Renewal (R07)

Renewal Products (cont.)

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StructuresNondestructive Testing for Concrete Bridge Decks (R06A) Nondestructive Testing for Tunnel Linings (R06G)Service Life Design for Bridges (R19A)Innovative Bridge Designs for Rapid Renewal (R04)GeoTechTools (R02)Nondestructive Testing for Concrete Bridge Decks (R06A)

Utilities and RailroadsIdentifying and Managing Utility Conflicts (R15B)Railroad–DOT Mitigation Strategies (R16)*A 2014 Every Day Counts product

Capacity Products

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Capacity ProductsImplementing Eco-Logical (C06) Expediting Project Delivery (C19)Economic Analysis Tools (C03/C11)Freight Demand Modeling and Data Improvement (C20)Advanced Travel Analysis Tools for Integrated Travel Demand Modeling (C10/C04/C05/C16)

Reliability Products

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Reliability ProductsOrganizing for Reliability Tools (L01/L06)Reliability Data and Analysis Tools (L02/L05/L07/L08/C11)Coordinated Training for Traffic Incident Responders and Managers (L12/L32) *A 2012 Every Day Counts product

Safety Products

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Safety ProductsConcept to Countermeasure – Research to Deployment Using the SHRP2 Safety Data

q 10 State DOTs received assistance to start 11 research projects using the SHRP2 Naturalistic Driving and Roadway Information Databases (phase I: Jan.-Sep. 2015)

q Research goalCreation of better safety:

q Policiesq Technologiesq Countermeasures

Module SHRP2 R23

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R23: Pavement Renewal Solutionsq Problem:q Guidance is needed to help better

understand when and where it can bebeneficial to use existing pavements tospeed rehabilitation project delivery.

q However, This is not always a viable solution.

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R23: Pavement Renewal Solutionsq Solution:q SHRP2 R23 project was initiated with the

objective of:q “developing reliable procedures that identify when

existing pavements can be used in place and themethods necessary to incorporate the originalmaterial into the new pavement structure whileachieving long life.”

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What is meant by long pavement life?q Pavements that significantly extend

current pavement design life by restrictingdistress, such as cracking and rutting, tothe pavement surface.

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Existing Renewal Approaches

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Existing Renewal Approachesq HMA over HMA renewal methods:

1. HMA over existing HMA pavement2. HMA Over reclaimed HMA (Recycling)

q Types of HMA mixes that can be used for renewal purposes:1. Stone matrix asphalt (SMA).2. Open graded friction course (OGFC).3. SuperPave Hot Mix Asphalt (HMA).

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HMA over Existing HMA Pavementq Used if there is no visible distress in

the existing HMA pavement other than that in isolated areas

q Existing pavement should also be structurally sound, level, clean, and capable of bonding to the overlay.

q Milling might be required, when?

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HMA over Reclaimed HMAq Used if the existing HMA layer is in

very poor condition and cracks are very deep in the pavement.

q Existing pavement is pulverized and reused, through introducing a binding agent, as a base layer.

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Stone Matrix Asphalt (SMA)q Specified Materials:q Coarse Aggregates:

q Aggregate retained on the No. 4 sieve. q Virgin aggregate shall be 100% crushed

material.q Max “flat and elongated %”:

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Test Method & Description % of Flat and ElongatedParticles in Coarse Aggregate

Flat and Elongated % by Count 3:1 (max to min) ASTM D4791 20%

Flat and Elongated % by Count 5:1 (max to min) ASTM D4791 5%


q Soundness: the percent degradation of the source aggregate by the sodium sulfate soundness test (AASHTO T104) after five cycles of testing shall not exceed 10%.

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q Deleterious materials and absorption shall not exceed:

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Test Method & Description PercentageClay Lump and Friable Particles (AASHTO T112) 0.25%

Absorption (passing 0.75 in. sieve and retained on No.4) (AASHTO T85) 2.0%


q LA Abrasion: the percent loss of thecoarse aggregate by the LA Abrasiontest (AASHTO T96) shall not exceed40%.

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Stone Matrix Asphalt (SMA)q Specified Materials:q Fine Aggregates:

q Shall be 100% crushed materialsconforming to the followingspecifications:

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Test Method & Description Minimum MaximumUncompacted Voids % (AASHTO T304) 45% 100%Sand Equivalent % (AASHTO T176) 50% 100%Liquid Limit % (AASHTO T89) 0% 25%Plasticity Index (AASHTO T90) Non-Plastic

Stone Matrix Asphalt (SMA)q Specified Materials:q Fine Aggregates:

q Shall have a maximum of 1.0% claylumps and friable particles asdetermined by AASHTO T112.

q It shall consist of hard, though grainsfree of deleterious substances.

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Stone Matrix Asphalt (SMA)q Specified Materials:q Mineral Filler:

q Shall consist of finely divided mineralmatter such as crusher fines, road dust,slag dust, hydrated lime, hydrauliccement, or fly ash (Class F) meeting therequirements of AASHTO M17.

q Any lime based product shall meet therequirements of AASHTO M303.

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Stone Matrix Asphalt (SMA)q Specified Materials:q Aggregate Gradation:

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Sieve Size

0.5 in. 0.375 in.lower upper Lower Upper

0.75 in. 100% 100% -- --0.5 in. 90% 100% 100% 100%0.375 in. 26% 78% 90% 100%No. 4 20% 28% 26% 60%No. 8 16% 24% 20% 28%No. 16 13% 21% 13% 21%No. 30 12% 18% 12% 18%No. 50 12% 15% 12% 15%No. 200 8% 10% 8% 10%

Stone Matrix Asphalt (SMA)q Specified Materials:q Asphalt Binder:q Shall be polymer modified and meet local

PG binder temperature requirements.q Maximum liquid asphalt binder drain-

down of 0.3% or less when tested inaccordance with AASHTO T305.

q Binder content typically ranges between6 to 7.5%.

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Stone Matrix Asphalt (SMA)q Specified Materials:q Mix Design:q Superpave using 50 gyrationsq Marshall design using 50 blowsq Shall have a minimum VMA of 17 and air

voids (Va) of 4.0%.q Shall have a minimum tensile strength

ratio of 70% (tested samples arefabricated at 6% voids).

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Open Graded Friction Courseq Specified Materials:q Aggregates:q Shall be limited to 100% crushed, virgin

aggregates.q Shall meet the following gradation

requirements:

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Sieve Size %Passing By Weight0.75 in. 100%0.5 in. 85–100%0.375 in. 55–65%No. 4 10–25%No. 8 5–10%No. 200 2–4%

Open Graded Friction Courseq Specified Materials:q Asphalt Binder:q Shall be polymer modified and meet local

PG binder temperature requirements.q Binder content typically ranges between

4.7 to 9.0%.q A fiber stabilizer shall be incorporated to

reduce drain-down.

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Open Graded Friction Courseq Specified Materials:q Mix Design:q Shall be designed with a minimum air

void content of 12%

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SuperPave Hot Mix Asphalt (HMA)q Specified Materials:q Asphalt Binder:q Use only PG graded binders (not higher

than PG 82-xx) in accordance withAASHTO M320.

q Aggregates:q Use AASHTO specification sections and

subsections unless local conditionsrequire otherwise.

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SuperPave Hot Mix Asphalt (HMA)q Specified Materials:q Mix Design:q Consider use of fine mix gradation which

can be defined as:q ½ in. NMAS: > 40 to 47% passing No. 8

sieveq AASHTO M323 has a different definition for

coarse and fine-graded mixtures.q Avoid use of 19 mm NMAS mixes unless

local performance is acceptableq TSR should be > 80% of AASHTO T283

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SuperPave Hot Mix Asphalt (HMA)q Specified Materials:q Mix Design:q Use AASHTO mix guidelines in AASHTO

M323 with a Va = 4.0%

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RePave Scoping Toolq The rePave Scoping Tool provide

Guidelines for Long Life PavementRenewal.

q The study, Scoping Tool, andaccompanying resources focus onlong life options (30-50 years).

q An example on how to use the toolwill be provided in class.

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Module SHRP2 R06A:

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R06A: Non-Destructive Testingq Problem:q Majority of concrete bridge decks in US is in

poor condition.q Evaluating bridge decks; thus, is very critical

as highway agencies work to optimize theeffective timing, scope, and approaches forpreventive maintenance, repair, andreplacement.

q Therefore, it is of great importance to theseagencies to determine appropriate non-destructive testing methods for concretebridge decks.

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R06A: Non-Destructive Testingq Solution:q SHRP2 R06A project was initiated with the

objective of developing:q “a web-based, open-source NDToolbox that helps in

identifying and characterizing testing technologiesthat are available to locate the primary deficienciesin concrete bridge decks. With the toolbox, userscan explore different NDT technologies andexamine their use in detecting deterioration forconditions relevant to the project.”

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Available Non-Destructive Concrete Bridge Deck Testing Technologies

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Available Technologiesq SHRP2 Module R06A has identified 14

potential technologies. These include:q Impact Echo;q Ultrasonic Pulse Echo;q Ultrasonic surface waves;q Impulse response;q Ground-penetrating radar;q Microwave moisture technique;q Eddy current;

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Available Technologiesq SHRP2 Module R06A has identified 14

potential technologies. These include:q Half-cell potential;q Galvanostatic pulse measurement;q Electrical resistivity;q Infrared thermography;q Visual inspection;q Chain dragging and hammer sounding;q Chloride concentration measurement.

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Impact Echo

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Impact Echo (Description)q It is a seismic or stress wave–based method

used in the detection of defects in concrete,primarily delamination.

q This method detects and characterizes wavereflectors or “resonators” in a concrete bridgedeck, or other structural elements.

q This is achieved by striking the surface of thetested object and measuring the response at anearby location (Pictures below).

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Impact Echo (Description)

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Stepper bridge deck scanner

Impact Echo (Physical Principal)q The surface of the deck is struck by various

means, such as wire-mounted steel balls,automated projectile sources, or solenoid-typeimpactors.

q The response is measured by a nearby contactor air-coupled sensor.

q The position of the reflectors is obtained fromthe frequency spectrum of the deck’s responseto an impact.

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Impact Echo (Physical Principal)

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Impact Echo (Applications)q The applications of Impact Echo can be

divided into four general categories asfollows:

q Condition assessment of reinforcedconcrete elements with respect todelamination;

q Characterization of surface-opening cracks(vertical cracks in bridge decks);

q Detection of ducts, voids in ducts, andrebars;

q Material characterization.49 49

Ultrasonic Pulse Echo (Description)q It is a method that uses ultrasonic

(acoustic) stress waves to detectobjects, interfaces, and anomalies.

q The waves are generated by exciting apiezoelectric material with a short-burst, high-amplitude pulse that hashigh voltage and current.

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Ultrasonic Pulse Echo (Physical Prin.)q Concentrates on measuring the transit

time of ultrasonic waves traveling througha material and being reflected to thesurface of the tested medium.

q Based on the transit time or velocity, thistechnique can also be used to indirectlydetect the presence of internal flaws, suchas cracking, voids, delamination orhorizontal cracking, or other damages.

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Ultrasonic Pulse Echo (Physical Prin.)

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Ultrasonic Pulse Echo (Applications)q Used previous for thickness measurements

on objects with only one-sided access.q Capable of assessing defects in concrete

elements, debonding of reinforcement bars,shallow cracking, and delamination.

q The UPE was also successfully used in thedetection of material interfaces, based onphase evaluations of the response.

q Examples include:q concrete and steel (e.g., reinforcement)q concrete and air (e.g., grouting defects)

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Ultrasonic Surface Waves (Decript.)q The ultrasonic surface waves (USW)

technique is an offshoot of the spectralanalysis of surface waves (SASW) methodused to evaluate material properties (elasticmoduli) in the nearsurface zone.

q The SASW uses the phenomenon of surfacewave dispersion (i.e., velocity of propagationas a function of frequency and wavelength,in layered systems to obtain informationabout layer thickness and elastic moduli).

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Ultrasonic Surface Waves (Phys. Prin.)q Surface waves are elastic waves that

travel along the free surface of a medium.q They carry a predominant part of the

energy on the surface, in comparison tobody (compressive and shear) waves.

q The arrival of the surface (Rayleigh)wave follows the arrival of the twobodywave components because it isthe slowest one (Figure below).

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Ultrasonic Surface Waves (Phys. Prin.)

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Ultrasonic Surface Waves (Phys. Prin.)

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Ultrasonic Surface Waves (Apps.)q The USW is used in condition assessment

for the purpose of evaluating probablematerial damage from various causes.

q It is also used in material quality control andquality assurance of concrete and hot-mixasphalt, primarily to evaluate materialmodulus and strength, the second one usingcorrelations with modulus.

q One of the USW’s applications is themeasurement of the depth of vertical(surface) cracks in bridge decks or otherelements.

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Impulse Response (Description)q The impulse response method is a nondestructive

testing method that has been mostly used in qualitycontrol and condition assessment of pavements anddeep foundations.

q The method was first developed in France in the late1970s as an extension of a vibration test, used in thequality control of drilled shafts.

q Since then, the impulse response method has beenused to determine the subgrade modulus andpresence of voids or loss of support below rigidpavements, concrete tunnel linings and slabs, and inreinforced concrete bridges.

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Impulse Response (Physical Principal)

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Impulse Response (Applications)q The impulse response method has been used in a

number of pavement and bridge applications. Theseinclude the following:

q Detection of low-density concrete (honeycombing) andcracking in concrete elements;

q Detection of voids under joints of rigid pavements or underslabs;

q Concrete delamination in slabs, decks, walls, and otherreinforced concrete structures, such as dams, chimneystacks,and silos;

q Load transfer at joints of concrete pavements; andq Debonding of asphalt and concrete overlays on concrete deck

and pavements.

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Ground-Penetrating Radar (Description)q Ground-penetrating radar (GPR) is a rapid

NDT method that uses electromagneticwaves to locate objects buried inside thestructure and to produce contour maps ofsubsurface features.

q Antennas of different frequencies are usedto facilitate different levels of needed detailand depth of penetration.

q In addition to ground-coupled antennas, air-coupled systems are used for faster bridgedeck screening.

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Ground-Penetrating Radar (Physical Prin.)q Ground-penetrating radar provides an

electromagnetic (EM) wave-reflection survey.q A GPR antenna transmits high-frequency EM

waves into the deck or the structure.q A portion of the energy is reflected back to the

surface from any reflector, such as rebar (or anyother anomaly), and received by the antenna.

q The remainder of the GPR energy continues topenetrate beneath this interface, and additionalenergy is continually reflected back to the receiverfrom other interfaces until it is diminished.

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Ground-Penetrating Radar (Physical Prin.)

64 64

Ground-Penetrating Radar (Physical Prin.)

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Ground-Penetrating Radar (Applications)q GPR has been used in a range of applications,

such as:q condition assessment of bridge decks and tunnel linings,q pavement profiling (pavement layer thickness evaluation),q detection of voids and anomalies under pavements,q mine detection, andq archaeological investigations.

q Typical GPR applications for bridge decks include:q evaluation of the deck thickness,q measurement of the concrete cover and rebar

configuration,

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Ground-Penetrating Radar (Applications)q Typical GPR applications for bridge decks include:

q characterization of delamination potential,q characterization of concrete deterioration,q description of concrete as a corrosive environment, andq estimation of concrete properties.

67 67

Half-Cell Potential (Description)q The half-cell potential (HCP) measurement is a well

established and widely used electrochemicaltechnique to evaluate active corrosion in reinforcedsteel and prestressed concrete structures.

q The method can be used at any time during the lifeof a concrete structure and in any kind of climate,provided the temperature is higher than 2°C.

q Using empirical comparisons, the measurementresults can be linked to the probability of activecorrosion.

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Half-Cell Potential (Description)

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Half-Cell Potential (Physical Prin.)q When a metal is submerged into an electrolyte,

positive metal ions will resolve (oxidation).q Oxidation leads to a surplus of electrons in the metal

lattice and a net negative charge at its surface.q The positive metal ions will accumulate at the metal–

liquid interface, which in consequence becomespositively charged, and a double layer is formed.

q Anions, from the electrolytic solution (in concrete –Cl-and –SO4 2-), are attracted to the positively chargedside of this double layer and accumulate there,forming the so-called half-cell.

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Half-Cell Potential (Physical Prin.)q A potential difference between the metal and

the net charge of the anions in the electrolytebuilds up, which depends on the solubility of themetal and the anions present in the solution.

q If two different metals are submerged into anelectrolyte (two half-cells) and are electricallyconnected by a wire, a galvanic element iscreated.

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Half-Cell Potential (Physical Prin.)q The two different metals will cause different

electrical potentials in their half-cells, which inturn will cause a current flow through the wire.

q The less noble of the two metals is dissolved(anode) and the more noble remains stable(cathode). In the surface layer of the less noblemetal, a surplus of electrons is formed.

q The potential difference between the two metalscan be measured as a voltage with a high-impedance voltmeter.

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Half-Cell Potential (Physical Prin.)

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Half-Cell Potential (Application)q The main application of the method is to identify

the corrosion activity of steel reinforcement insteel-reinforced concrete structures.

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Galvanostatic Pulse Measurement (Description)

q Galvanostatic pulse measurement (GPM) is anelectrochemical NDT method used for rapidassessment of rebar corrosion, based on thepolarization of rebars using a small currentpulse.

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Galvanostatic Pulse Measurement (Phys. Prin.)

q When a metal, such as steel reinforcement, isimmersed in an electrolytically conducting liquidof adequate oxidizing power, it undergoescorrosion by two complementary mechanisms.

q First, metal ions pass into the liquid, leaving asurplus of electrons on the base metal thatforms an anodic site.

q Second, the excess electrons flow to a cathodicsite where they are consumed by oxidizingagents in the liquid. These processes induce acorrosion current between the anodic andcathodic sites. 76 76


q The corrosion current can be indirectlymeasured by galvanostatically (with constantcurrent) imposing a short-time anodic currentpulse between a counter electrode at theconcrete surface and the steel reinforcement.

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Galvanostatic Pulse Measurement (Application)

q The GPM is used primarily to identify thecorrosion rate of steel reinforcement inreinforced concrete structures.

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Electrical Resistivity (Description)

q The electrical resistivity (ER) method is oftenused for moisture detection, which can belinked to the presence of cracks.

q The presence and amount of water andchlorides in concrete are important parametersin assessing its corrosion state or describing itscorrosive environment.

q Damaged and cracked areas, resulting fromincreased porosity, are preferential paths forfluid and ion flow.

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Electrical Resistivity (Description)

q The higher the ER of the concrete is, the lowerthe current passing between anodic andcathodic areas of the reinforcement will be.

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Electrical Resistivity (Physical Principal)

q In practice, the voltage and current aremeasured at the surface of the object underinvestigation.

q The most common electrode layout in civilengineering applications is the Wenner setup.

q The Wenner setup uses four probes that areequally spaced.

q A current is applied between the outerelectrodes, and the potential of the generatedelectrical field is measured between the twoinner ones.

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Electrical Resistivity (Principal)

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Electrical Resistivity (Physical Principal)

q In practice, the voltage and current aremeasured at the surface of the object underinvestigation.

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Electrical Resistivity (Applications)

q Electrical resistivity is primarily used tocharacterize concrete’s susceptibility tocorrosion by characterizing its corrosiveenvironment.

q It can also help to identify regions of the deck orother structural elements susceptible to chloridepenetration.

q Electrical resistivity surveys can be used todetect corrosion cells in tandem with anothercorrosion technique, such as half-cell potential,to map corrosion activity.

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Infrared Thermography (Description)

q Infrared (IR) thermography has been used sincethe 1980s to detect concrete defects, such ascracks, delaminations, and concretedisintegration in roadways or bridge structures.

q To detect subsurface defects, IR thermographykeeps track of electromagnetic wave surfaceradiations related to temperature variations in theinfrared wavelength.

q Anomalies, such as voids and material changes,can be detected on the basis of variable materialproperties, such as density, thermal conductivity,and specific heat capacity.

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Infrared Thermography (Description)

q The resulting heating and cooling behavior iscompared with the surrounding material.

q Infrared cameras measure the infrared radiation(wavelength ranging from 0.7 to 14 μm) that isemitted by a body, and this radiation is thenconverted into an electrical signal.

q These signals are further processed to createmaps of surface temperature.

q A qualitative data analysis can be done from thethermograms (temperature coded images).

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Infrared Thermography (Physical Principal)

q Infrared radiation is part of the electromagneticspectrum, with the wavelength ranging from 0.7to 14 μm.

q Infrared cameras measure the thermal radiationemitted by a body, based on the thermalproperties of various materials, and capture theregions with temperature differences.

q The three main properties that influence theheat flow and distribution within a materialinclude the thermal conductivity (l), specific heatcapacity (Cp), and the density (r).

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Infrared Thermography (Applications)

q Infrared thermography is mostly used to detectvoids and delaminations in concrete.

q However, it is also used to detect delaminationsand debonding in pavements, voids in shallowtendon ducts (small concrete cover), cracks inconcrete, and asphalt concrete segregation forquality control.

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Infrared Thermography (Applications)

90 90

Chain Dragging and Hammer Sounding (Description)

q Chain dragging and hammer sounding are themost common inspection methods used bystate DOTs and other bridge owners for thedetection of delaminations in concrete bridgedecks.

q The objective of dragging a chain along thedeck or hitting it with a hammer is to detectregions where the sound changes from a clearringing sound (sound deck) to a somewhatmuted and hollow sound (delaminated deck).

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Chain Dragging and Hammer Sounding (Description)

q Chain dragging is a relatively fast method fordetermining the approximate location of adelamination.

q The speed of chain dragging varies with thelevel of deterioration in the deck.

q Hammer sounding is much slower and is usedto accurately define the boundaries of adelamination.

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Chain Dragging and Hammer Sounding (Physical Prin.)

q Chain dragging and hammer sounding arecategorized as an elastic wave test.

q The operator drags chains on the deck,listening to the sound the chains make.

q A clear ringing sound represents a sound deck,while a muted or hollow sound represents adelaminated deck.

q The hollow sound is a result of flexuraloscillations in the delaminated section of thedeck, creating a drumlike effect.

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q Flexural oscillation of a deck resulting from animpact (the source of the impact can either befrom chain dragging or hammer sounding) istypically found to be in a 1- to 3-kHz range.

q This is within the audible range of a human ear.q The presence of any delamination changes the

frequency of oscillation and, therefore, theaudible response of the deck.

94 94


95 95

Chain Dragging and Hammer Sounding (Applications)

q Chain dragging and hammer sounding aremainly used to detect the late stages ofdelaminations in concrete structures.

q Although chain dragging is limited to horizontalsurfaces, hammer sounding can be used for awider range of structures.

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SHRP2 R06A Main Conclusions

q From a number of deterioration types, thefollowing four types were given the highestpriority for concrete bridge decks

q Delamination: impact echo, chain dragging andhammer sounding, ultrasonic pulse echo, infraredthermography, and ground-penetrating radar.

q Corrosion: half-cell potential, electrical resistivity,and galvanostatic pulse measurement.

q Vertical crack: visual inspection, ultrasonicsurface waves, ultrasonic pulse echo, andimpact echo.

97 97

SHRP2 R06A Main Conclusions

q From a number of deterioration types, thefollowing four types were given the highestpriority for concrete bridge decks

q Concrete degradation: ultrasonic surface wavesand pulse echo, impact echo, and ground-penetrating radar.

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Module SHRP2 R19

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R019 Service Life Design for bridgesq Problem:q Because of deterioration, individual bridge

components and systems such as bearings,decks, joints, columns, and girders requirefrequent and costly inspections, maintenance,and repairs that are often difficult to conduct.

q These activities cause lane closures thatcreate congestion and impact safety for roadworkers and motorists.

q Bridge engineers need improved designoptions so they can deliver bridges that areoperational for 100 years or more.

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R019 Service Life Design for bridgesq Solution:q SHRP2 R19 project was initiated with the

objective of:q “developing a Guide that will provide information

and guidance and define procedures tosystematically approach service life and durabilityfor both new and existing bridges..”

101 101

General Design for Service Life Framework

102 102

Basic Terminology

103 103

Service Life and Designq Service life: The time duration during

which the bridge element, component,subsystem, or system provides thedesired level of performance orfunctionality, with any required level ofrepair or maintenance.

104 104

Service Life and Designq Target design service life: The time

duration during which the bridge element,component, subsystem, and system isexpected to provide the desired functionwith a specified level of maintenanceestablished at the design or retrofit stage.

105 105

Service Life and Designq Design life: The period of time on which

the statistical derivation of transient loadsis based: 75 years for the current versionof AASHTO LRFD Bridge DesignSpecifications (2012), referred tothroughout the Guide as LRFDspecifications.

106 106

Bridge Element, Component, Subsystem, and System

q Bridge element: Individual bridgemembers such as a girder, floor beam,stringer, cap, bearing, expansion joint,railing, and so forth. Combined, theseelements form subsystems andcomponents, which then constitute abridge system.

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q Bridge component: A combination ofbridge elements forming one of the threemajor portions of a bridge that makes upthe entire structure. The three majorcomponents of a bridge system aresubstructure, superstructure, and deck.

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q Bridge subsystem: A combination of twoor more bridge elements acting togetherto serve a common structural purpose,such as a composite girder, which couldconsist of girder, reinforcement, andconcrete.

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q Bridge system: The three majorcomponents of the bridge (deck,substructure, and superstructure)combined to form a complete bridge.

110 110

Approach to Design for Service Life

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112 112

113 113

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Approach to Design for Service Lifeq Step 1. The design for service life starts

by considering all project demands set bythe owner, including the service liferequirements, as stated in Figure above.

115 115

Approach to Design for Service Lifeq Step 2. All feasible and preliminary bridge

alternatives that satisfy project demandsshould be developed. For example, onemight want to consider steel, concrete,and segmental bridge alternatives for aparticular bridge. The development of thepotential bridge system is carried out in aconventional manner, meeting all theprovisions of the LRFD specifications.

116 116

Approach to Design for Service Lifeq Steps 3 and 4. The next steps in the

process consist of evaluating each bridgesystem alternative one at a time andconsidering service life issues related toeach element, component, andsubsystem of that bridge system.

117 117

Approach to Design for Service Lifeq Steps 5 through 8. At the end of Step 4

and after going through appropriate faulttrees for various bridge elements,components, and subsystems, thedesigner will have developed a bridgesystem that meets both strength andservice life requirements. To some extent,changes to configurations of variousbridge elements, components, andsubsystems are carried out separately.

118 118

Approach to Design for Service Lifeq Steps 9 through 12. The next step in the process

is to evaluate the service lives of the variousbridge elements, components, and subsystems ofthe bridge alternative under consideration andcompare its overall service life with the owner-specified target service design life of the bridgesystem.

q For example, the owner may require that thebridge provide 100 years of service life, but thelife of a particular bridge element, such as thesliding surface for a bearing, may be limited to 20years. This situation would require a plan fortimely replacement of the sliding surfaces.

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New Composite Pavement Systems

Module SHRP2 R21

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R21: New Composite Pavement Systemsq Problem:q Many agencies today are faced with the

challenge of being sustainable (that is, usingrecycled materials) and economical inrehabilitating pavements, while also providing fora long service life.

q A few agencies today also face the challenge ofhaving a limited source of quality aggregates,thus having the added cost of importing materials.

q Pavements that combine new asphalt overconcrete, and/or 2 lift concrete generally have along service life with excellent surfacecharacteristics, structural capacity, and the abilityto be rapidly renewed.

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R21: New Composite Pavement Systemsq Problem:q However, the majority of roads containing

these composite pavements resulted frommaintenance and rehabilitation activities.

q Therefore, U.S. Transportation agenciesrequire guidance, specifications, objectiveand reliable performance data, and life-cycle cost analyses to support use of thesepavement systems.

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R21: New Composite Pavement Systemsq Solution:q SHRP2 R21 project was initiated to provide

detailed performance data on existingcomposite pavement systems, and offersstep-by-step guidance on two types ofcomposite pavements (Hot-Mix Asphalt(HMA) over Portland Cement Concrete(PCC) and PCC over PCC usingprocedures consistent with theMechanistic-Empirical Pavement DesignGuide (MEPDG).

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HMA over PCC Design Guidelines and Examples

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Pavement ME Design Guidelinesq General Use of Pavement ME:q Design Type: Select “AC Overlay”. Although a

new composite pavement is being designedand not an overlay, this is the proper DesignType to select until a Design Type specificallyfor new composite pavement is added byAASHTO.

q Pavement Type:q Select “AC/JPCP” for AC/JPC and AC/RCC

composite pavements.q Select “AC/CRCP” for AC/CRC composite

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Pavement ME Design Guidelinesq General Use of Pavement ME:q Design Life: Select desired life of structural

design until major rehabilitation is needed.Composite pavements are very appropriate toa long structural life, exhibiting little structuraldeterioration over many years.

q DARWin-ME can design pavements for adesign life as long as 100 years.

q To design a “long-life” pavement, select alonger life of more than 40 years.

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Pavement ME Design Guidelinesq Trial Design (Design Reliability)q Design reliability and performance for

composite pavements.q Design reliability should be based on traffic level of

the highway. Higher traffic levels warrant higherreliability levels.

q Interstates, freeways, divided highways: 95% to 99%;q Other highways and urban collectors/arterials: 90% to

94%; andq Local residential and farm-to-market roads: 75% to

89%.

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Pavement ME Design Guidelinesq Trial Design (Design Reliability)q Structural fatigue cracking and punchouts:

q JPCP: 10% slabs (range, 5% to 15%) transverse fatiguecracking; and

q 2. CRCP: 10 punchouts per mile (range, 5% to 15%).q Smoothness, Terminal IRI should be based on traffic

level of the highway. Higher traffic levels warrantlower terminal smoothness levels.

q Interstates, freeways, divided highways: 150 in./mile;q Other highways and urban collectors/arterials: 160

in./mile; andq Local residential and farm-to-market roads: 175 in./mile.

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Pavement ME Design Guidelinesq Trial Design (Design Reliability)q Permanent deformation (rutting of HMA only,

which is total also): This should be 0.50-in.mean wheelpath.

q Joint faulting for bare JPCP comparisons:This should be 0.15 to 0.20 in.

q Initial IRI: The initial IRI for HMA/PCCcomposite pavements can be very lowbecause of the multiple layering of thepavement. Initial IRI values as low as 35in./mile have been achieved, with routinevalues from 40 to 50 in./mile.

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Pavement ME Design Guidelinesq Trial Design (Design Reliability)q Type and thickness of HMA surface layer:q The type depends on the design objectives.q If reducing noise levels to a minimum is

required, some type of porous asphalt surfacecan be used.

q Thickness should be the minimum possible toprovide durability and surface characteristicsdesired for a given truck traffic and climate.

q In warmer weather locations, a thinnersurfacing is feasible, such as 1 in., but forcolder weather and heavier traffic, as much as3 in. total may be required.

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Pavement ME Design Guidelinesq Trial Design (Type and Thickness of PCC)q This is the load carrying capacity layer for the

composite pavement.q The trial design should start with a typical

thickness used for bare pavement.q Depending on the thickness of the HMA

surface, the slab thickness may be reducedby 1 to 3 in. of concrete.

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Pavement ME Design Guidelinesq Trial Design (Joint Design for JPCP)q Joint spacing is considered directly in the

Pavement ME analysis and affects transversefatigue cracking as well as joint faulting. Ashorter slab has two distinct advantages:

q Thinner slab to control cracking; andq Less joint reflection cracking and deterioration

through the HMA surface. For nondoweled joints,the shorter the joint spacing, the higher the jointload transfer efficiency, reducing the deterioration ofthe reflection crack.

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Pavement ME Design Guidelinesq Trial Design (Joint Design for JPCP)q Joint spacing is considered directly in the

Pavement ME analysis and affects transversefatigue cracking as well as joint faulting. Ashorter slab has two distinct advantages:

q Thinner slab to control cracking; andq Less joint reflection cracking and deterioration

through the HMA surface. For nondoweled joints,the shorter the joint spacing, the higher the jointload transfer efficiency, reducing the deterioration ofthe reflection crack.

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Pavement ME Design Guidelinesq Trial Design (Joint Design for JPCP)q Joint load transfer requirement is similar to

bare JPCP design in that dowels of sufficientsize are required to prevent erosion andfaulting for any significant level of truck traffic.The greater the dowel diameter, the higherthe joint load transfer efficiency and the moretruck loadings the pavement can carry to theterminal level of faulting.

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Pavement ME Design Guidelinesq Trial Design (Joint Design for CRC)q Joints should always be provided for RCC at

spacing even shorter than for JPCP (e.g., 10ft. is recommended).

q These joints will not have dowels and can beformed in various ways other than sawing.Joints do not require sealing or filling.

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Pavement ME Design Guidelinesq Trial Design (Reinforcement Design for CRC)q The reinforcement content should be similar

to bare CRCP.q All of the same crack spacing, long-term

width, and long-term load transfer efficiencyare applicable.

q If these recommendations are followed,HMA/CRC composite pavements have shownno reflection cracking over many years andwith very heavy traffic.

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Pavement ME Design Guidelinesq Trial Design (Concrete Slab

Recommendation)q The formed concrete or roller compacted

concrete to be used for the lower layer of anAC/PCC composite pavement can varywidely.

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Pavement ME Design Guidelinesq Trial Design (Base Layer and Other layers)q Should be selected similar to bare JPCP or

CRCP designs based on minimizing erosion,construction ease, and cost effectiveness.

q No attempts should be made to reduce thefriction between the slab and the basebecause good friction is required to form jointsin JPC/RCC and cracks in CRCP.

q Good friction also helps control erosion andpumping and reduces stress in the slab.

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Pavement ME Design Guidelinesq Trial Design (Results Interpretation)q Results to consider:

q JPCP and Jointed RCC: Transverse fatigue cracking,IRI, and HMA rutting must all meet the design reliabilityrequirements for a trial design to be feasible.

q CRCP: Edge punchouts, transverse crack width,transverse crack load transfer efficiency, IRI, and ruttingmust all meet the design reliability requirements for atrial design to be feasible.

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Pavement ME Design Guidelinesq Trial Design (Results Interpretation)q If any of these do not “Pass” at the reliability

level, a modification in the design is required.q Excess transverse cracking of JPC or jointed RCC slab:

increase slab thickness, shorten joint spacing, add a tiedPCC shoulder or 1-ft widened slab, use a stabilized basecourse, increase PCC strength (with appropriate changein the modulus of elasticity), or use a different aggregatesource (one with lower CTE).

q Excess punchouts for CRC: increase slab thickness,increase reinforcement content, use a tied PCC shoulderor 1-ft widened slab, use a stabilized base course, oruse a different aggregate source (one with lower CTE).

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level, a modification in the design is required.q Excess rutting of HMA surface: modify binder grade;

modify mixture parameters, such as as-built air voidsand binder content; and reduce layer thickness. If thesechanges are not effective or acceptable, program asurface removal and replacement at the point ofpredicted rutting reaching the critical level.

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level, a modification in the design is required.q Excess IRI: reduce JPC or jointed RCC transverse

cracking and HMA rutting, or require a smoother initialpavement.

q Composite pavements can be constructed with anexceptionally low initial IRI (e.g., 40 to 50 in./mile).

q Include incentive smoothness specifications withsignificant incentives so that the initial IRI is reduced.

q Smoothness incentives have been used with greatsuccess over several decades to improve initial IRI.

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Illustrative Example Using Pavement ME

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Example Inputs

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Example Inputs

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Example Inputs

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