sponsored by · [email protected] rodden, rob american concrete pavement assn usa...

Sponsored By: Federal Aviation Administration FAA Center for Excellence for Airport Technology at the University of Illinois Illinois Center for Transportation at the University of Illinois University of Illinois at Urbana‐Champaign International Society for Concrete Pavements Michigan Tech Transportation Institute at Michigan Technological University Pavement Research Institute at the University of Minnesota University of California Pavement Research Center

University of CaliforniaBerkeley

Richmond Field Station Richmond, CA, USA

August 13‐15, 2008

SECOND WORKSHOP ON ADVANCED CHARACTERIZATION, MODELING, AND DESIGN OF CONCRETE PAVEMENTS UNIVERSITY OF CALIFORNIA-BERKELEY RICHMOND FIELD STATION RICHMOND, CALIFORNIA, USA AUGUST 13-15, 2008

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Table of Contents: Objective .......................................................................................................................... 4 Workshop Background ..................................................................................................... 4 Workshop Format ............................................................................................................ 4 Workshop Benefits ........................................................................................................... 4 Workshop Personnel ........................................................................................................ 5 Acknowledgements .......................................................................................................... 5 List of Participants ............................................................................................................ 6 Planning Schedule ............................................................................................................ 7 Maps of the Richmond Field Station ................................................................................ 8 Technical Program ......................................................................................................... 10 Disclaimer ....................................................................................................................... 13 Application of Nanotechnology to Concrete Pavement ................................................. 14

Surendra Shah Northwestern University

Addressing Erosion‐Related Distresses in Concrete Pavement Design .......................... 16 Dan Zollinger Texas A&M University

Moving Beyond Empirical Models for Behavior of Early Age Concrete ......................... 17 David Lange University of Illinois

Experiences and Challenges for China’s Concrete Pavement Network .......................... 18 Bo Tian Research Institute of Highway

Moisture Warping in Concrete Pavements .................................................................... 19 Will Hansen University of Michigan

Potential Relative Humidity and Temperature Gradient Effects on Diamond‐Ground Concrete Pavements ...................................................................................................... 20 Rob Rodden American Concrete Pavement Assn.


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Influence of Concrete Mixture and Admixture on Shrinkage ......................................... 21 Ali Farhang Swedish Cement & Concrete Research Institute

Core‐Ring Model Analysis for Residual Stress in Concrete Beams ................................. 22

Xinkai Li Harbin Institute of Technology Xiangshen Hou Harbin Institute of Technology Songlin Ma Harbin Institute of Technology Characterizing the Fracture Behaviour of Ultra‐thin Continuously Reinforced Concrete Pavements (UTCRCP) ..................................................................................................... 23

Erik Denneman CSIR Built Environment Elsabe P. Kearsley University of Pretoria Alex T. Visser University of Pretoria

Experimental Validation of Computed Load‐Induced Deflections and Strains in Concrete Pavement Slabs .............................................................................................................. 24

Kitti Manokhoon University of Florida Mang Tia University of Florida Bouzid Choubane Florida Department of Transportation Michael Bergin Florida Department of Transportation

Selected Results in Mechanics of Concrete and Concrete Structures Obtained under Supervision of Prof. V.D. Kharlab ................................................................................... 25

Lev Kagan‐Rozentsveyg St. Petersburg State University of Architecture and Civil Engineering

Characterization and Impact of Built‐in Curling on Rigid Pavement Response ............. 26

Jake Hiller Michigan Technological University Indications of the Effect of Coefficient of Thermal Expansion on Cracking of Jointed Concrete Pavements ...................................................................................................... 27

Erwin Kohler Dynatest Consulting, Inc. FWD Consideration of Environmental Effects in the Backcalculation of Jointed Plain Concrete Pavement Layer Moduli and the Associated Challenges ................................ 28

Mustafa Birkan Bayrak Iowa State University Halil Ceylan Iowa State University

Failure Model Improvement for PCC Pavements ........................................................... 30 Edward Guo SRA International


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Durable Construction by Help of a Semi‐Probabilistic System and Differentiated Inputs into Thickness Design ............................................................................................................ 31

Stephan Villaret Villaret Ingenieurgesellschaft mbH A Framework using DAKOTA and MEPDG for the Probabilistic Analysis of Pavements 32

Steve Wojtkiewicz University of Minnesota Mechanistic Modeling of Pavement Performance for Pavement Design ..................... 33

Tom Yu U.S. Federal Highway Administration Calibration of MEPDG Cracking Models ........................................................................ 34

John Harvey University of California‐Davis Implementation of Fatigue Models for the Design of Concrete Pavements in Brazil .... 35

Jose Balbo University of Sao Paulo Flexural Capacity of Concrete Slabs ............................................................................... 36

Jeff Roesler University of Illinois Cristian Gaedicke University of Illinois

NAPTF Unbonded Concrete Overlay Testing: Challenges and Issues in Materials ........ 37

Shelley Stoeffels Pennsylvania State University Laboratory and Finite Element Modeling of Joint Lockup ............................................. 38

Lev Khazanovich University of Minnesota


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Objective:

This workshop aims to bring together experts in concrete materials characterization, mechanics, modeling, and design to critically discuss and develop concepts to address existing limitations, lack of knowledge, and future direction for improvement of concrete pavement analysis, design, and construction.

Workshop Background:

This workshop will be the second in a series of fundamental workshops sponsored in part by the International Society for Concrete Pavements (ISCP). The first in this series of workshops was held in Copper Mountain, Colorado, USA in August 2005. The theme of the 2008 workshop will be “Advanced Characterization, Modeling, and Design of Concrete Pavements”.

Workshop Format:

Three invited keynote presentations summarizing the state‐of‐the art in concrete pavement and material modeling, testing, and relevant applications will be presented by Dr. David Lange (University of Illinois, USA) and Dr. Bo Tian (Research Institute of Highway, China) on Thursday morning and Dr. Lev Kagan‐Rozentsveyg (St. Petersburg State University of Architecture and Civil Engineering, Russia) on Friday morning.

In addition to the keynote addresses, 23 presentations are scheduled representing 8 countries around the globe. Each presenter will make a 10‐minute presentation and lead a subsequent 10‐minute group discussion on the topic.

Recommendations to the 9th International Conference on Concrete Pavements (August 17‐21 in nearby San Francisco) will be discussed and formalized at the end of the workshop.

Workshop Benefits:

USD$315 workshop fee includes: Breakfast (2), Lunch (2), and Dinner (2) on Thursday and Friday as well as the Wednesday night reception are also included in the workshop fees.

Each attendee will receive a program of the workshop abstracts that were submitted by participants.


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Workshop Personnel:

Workshop Chairmen: Lev Khazanovich University of Minnesota Jeff Roesler University of Illinois

Workshop Secretary: Jake Hiller Michigan Technological University

Workshop Steering Committee: José Balbo University of Sáo Paulo David Brill Federal Aviation Administration Ali Farhang Swedish Cement & Concrete Research Institute Carl Monismith University of California‐Berkeley Jim Signore University of California‐Berkeley Mark Snyder Consultant Tom Yu Federal Highway Administration

Acknowledgements:

The workshop chairmen, secretary, and steering committee would like to acknowledge the financial and human support given by many individuals and organizations to make this workshop a reality. A special thanks also goes out to the University of California Pavement Research Center (UCPRC) for hosting the workshop in their facilities at the Richmond Field Station.


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List of Participants:

Name Organization Country email

Balbo, Jose University of São Paulo Brazil [email protected]

Beyer, Matt University of Illinois USA [email protected]

Bordelon, Amanda University of Illinois USA [email protected]

Cervantes, Victor University of Illinois USA [email protected]

Ceylan, Halil Iowa State University USA [email protected]

Covarrubias, Juan Pablo TCPavements Ltda Chile [email protected]

Darter, Mike Applied Research Associates, Inc. USA [email protected]

Denneman, Erik CSIR Built Environment South Africa [email protected]

Evangelista, Junior University of Illinois USA [email protected]

Farhang, Ali Swedish Cement and Concrete Research Institute

Sweden [email protected]

Gaedicke, Cristian University of Illinois USA [email protected]

Gotlif, Alex Applied Research Associates, Inc. USA [email protected]

Guo, Ed SRA International, Inc. USA [email protected]

Hansen, Will University of Michigan USA [email protected]

Harvey, John University of California‐Davis USA [email protected]

Heogh, Kyle University of Minnesota USA [email protected]

Hiller, Jake Michigan Technological University USA [email protected]

Kagan‐Rozentsveyg, Lev St. Petersburg State University of Architecture and Civil Engineering

Russia [email protected]

Khazanovich, Lev University of Minnesota USA [email protected]

Kohler, Erwin Dynatest Consulting, Inc. USA [email protected]

Lange, David University of Illinois USA [email protected]

Li, Xinhai Harbin Institute of Technology P.R. China [email protected]

Liu, Yi Shi University of Illinois USA [email protected]

Monismith, Carl University of California‐Berkeley USA [email protected]

Nganjo, Peter BKS (Pty) Ltd South Africa [email protected]

Rodden, Rob American Concrete Pavement Assn USA [email protected]

Roesler, Jeff University of Illinois USA [email protected]

Saxena, Priyam University of Minnesota USA [email protected]

Shah, Surendra Northwestern University USA s‐[email protected]

Signore, Jim University of California‐Berkeley USA [email protected]

Snyder, Mark Consultant USA [email protected]

Stoffels, Shelley Pennsylvania State University USA [email protected]

Tia, Mang University of Florida USA [email protected]

Tian, Bo Research Institute of Highway P.R. China [email protected]

Tompkins, Derek University of Minnesota USA [email protected]

Vandenbossche, Julie University of Pittsburgh USA [email protected]

Villaret , Stephan Villaret Ingenieurgesellschaft mbH Germany [email protected]

Wojtkiewicz, Steve University of Minnesota USA [email protected]

Yu, Tom Federal Highway Administration USA [email protected]

Zollinger, Dan Texas A&M University USA d‐[email protected]

mailto:[email protected]







































Planning Schedule:

A short outline of the workshop events is provided below. A more detailed technical program can be found later in the program. Please note that California is on Pacific Daylight Time (GMT ‐8:00) during this workshop.

Wednesday, August 13 Thursday, August 14 Friday, August 15

7:30

8:00

8:30

9:00

9:30

10:00 Break Break

10:30

11:00

11:30

12:00

12:30

13:00

13:30

14:00

14:30

15:00 Break Break

15:30

16:00

16:30

17:00 Concluding Remarks

17:30

18:00

18:30

19:00

19:30

Arrival of participants and welcoming reception (Skate's Restaurant ‐

Berkeley)

Technical Session 2

Technical Session 4

Technical Session 5

Barbeque Dinner (Richmond Field Station)

Closing Banquet (Spinnaker Restaurant ‐ Sausalito)

Breakfast (provided at RFS)

Opening Session

1st and 2nd Keynote Addresses

Technical Session 1

Breakfast (provided at RFS)

Lunch (provided at RFS)

Technical Session 3

Lunch (provided at RFS)

3rd Keynote Address


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Maps of the Richmond Field Station:

The workshop will be held in Building #445 at the UC‐Berkeley Richmond Field Station near Egret Way and Wren Drive. A map of the Richmond Field Station can be found on the following page of your program. A map of the Richmond Area is also provided. Map and pictures courtesy of www.rfs.berkeley.edu


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http://www.rfs.berkeley.edu/


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Technical Program:

Wednesday, August 13, 2008 18:00 Welcoming reception (Skate’s on the Bay Restaurant, Berkeley) http://www.skatesonthebay.com/

Thursday, August 14, 2008: 7:45 Breakfast at Richmond Field Station

8:30 OPENING SESSION Opening Remarks

Dr. Jeff Roesler University of Illinois Dr. Lev Khazanovich University of Minnesota Prof. Carl Monismith University of California‐Berkeley Dr. Dan Zollinger Texas A&M University

Application of Nanotechnology to Concrete Pavement Dr. Surendra Shah Northwestern University

Addressing Erosion‐Related Distresses in Concrete Pavement Design Dr. Dan Zollinger Texas A&M University

10:00 Break

10:30 FIRST KEYNOTE ADDRESS Introduction: Dr. Jeff Roesler Moving Beyond Empirical Models for Behavior of Early Age Concrete

Dr. David Lange University of Illinois

11:15 SECOND KEYNOTE ADDRESS Introduction: Dr. Jeff Roesler Experiences and Challenges for China’s Concrete Pavement Network

Dr. Bo Tian Research Institute of Highway

12:00 Lunch at Richmond Field Station

13:30 TECHNICAL SESSION 1 Moderator: Dr. José Balbo Moisture Warping in Concrete Pavements

Dr. Will Hansen University of Michigan

Potential Relative Humidity and Temperature Gradient Effects on Diamond‐Ground Concrete Pavements

Rob Rodden American Concrete Pavement Assn.

Influence of Concrete Mixture and Admixture on Shrinkage Dr. Ali Farhang Swedish Cement & Conc. Research Institute

Core‐Ring Model Analysis for Residual Stress in Concrete Beams Xinkai Li Harbin Institute of Technology


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15:00 Break

15:30 TECHNICAL SESSION 2 Moderator: Dr. Jake Hiller Fiber‐Reinforced Concrete for Ultra‐Thin Whitetopping Applications

Dr. Julie Vandenbossche University of Pittsburgh

Thin Concrete Pavements Dr. Juan Pablo Covarrubias TCPavements Ltda

Characterizing the Fracture Behaviour of Ultra‐thin Continuously Reinforced Concrete Pavements (UTCRCP)

Erik Denneman CSIR Built Environment

Experimental Validation of Computed Load‐Induced Deflections and Strains in Concrete Pavement Slabs

Dr. Mang Tia University of Florida

18:00 Cookout dinner at Richmond Field Station

Friday, August 15, 2008: 7:45 Breakfast at Richmond Field Station

8:30 THIRD KEYNOTE ADDRESS Introduction: Dr. Lev Khazanovich Selected Results in Mechanics of Concrete and Concrete Structures Obtained under Supervision of Prof. V.D. Kharlab

Dr. Lev Kagan‐Rozentsveyg St. Petersburg State University of Architecture and Civil Engineering

Concrete Pavement Design and Construction at High Elevations Dr. Mike Darter ARA, Inc.

10:00 Break

10:30 TECHNICAL SESSION 3 Moderator: Dr. Will Hansen Characterization and Impact of Built‐in Curling on Rigid Pavement Response

Dr. Jake Hiller Michigan Technological University

Indications of the Effect of Coefficient of Thermal Expansion on Cracking of Jointed Concrete Pavements Dr. Erwin Kohler Dynatest Consulting, Inc.

Consideration of Environmental Effects in the Backcalculation of Jointed Plain Concrete Pavement Layer Moduli and the Associated Challenges

Dr. Halil Ceylan Iowa State University

Failure Model Improvement for PCC Pavements Dr. Edward Guo SRA International

12:00 Lunch at Richmond Field Station


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13:30 TECHNICAL SESSION 4 Moderator: Dr. Mark Snyder Durable Construction by Help of a Semi‐Probabilistic System and Differentiated Inputs into Thickness Design

Dipl.ing. Stephan Villaret Villaret Ingenieurgesellschaft mbH

A Framework using DAKOTA and MEPDG for the Probabilistic Analysis of Pavements Dr. Steve Wojtkiewicz University of Minnesota

Mechanistic Modeling of Pavement Performance for Pavement Design Tom Yu U.S. Federal Highway Administration

Calibration of MEPDG Cracking Models Dr. John Harvey University of California‐Davis

15:00 Break

15:30 TECHNICAL SESSION 5 Moderator: Dr. Dan Zollinger Implementation of Fatigue Models for the Design of Concrete Pavements in Brazil

Dr. Jose Balbo University of Sao Paulo

Flexural Capacity of Concrete Slabs Dr. Jeff Roesler University of Illinois

NAPTF Unbonded Concrete Overlay Testing: Challenges and Issues in Materials Characterization

Dr. Shelley Stoeffels Pennsylvania State University

Laboratory and Finite Element Modeling of Joint Lockup Dr. Lev Khazanovich University of Minnesota

17:00 WORKSHOP CONCLUDING REMARKS

18:00 Banquet dinner at the Spinnaker Restaurant in Sausalito http://www.thespinnaker.com/

Saturday, August 16, 2008: 9:30 Napa wine tour (vans leave from Doubletree Berkeley Marina hotel)


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Disclaimer:

This workshop program includes abstracts that have not been through a peer‐review process. Any material presented in these abstracts is the responsibility of the respective authors.


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Application of Nanotechnology to Concrete Pavement

Surendra P. Shah Northwestern University, Evanston, Illinois, USA Using nanotechnology, researchers are exploring ways to enhance the strength of concrete

pavement while at the same time make the product and production more environmentally

friendly. Three potential applications of nanotechnology, characterization, processing, and

sensor development, are discussed. Concrete pavement is constructed utilizing a slip‐cast

process. A possible drawback to this method is the use of internal vibration. Elimination of

internal vibration can lead to better durability, less noise pollution, and less energy

consumption. Jointly, with Iowa State University, my research group is working to

manipulate the composition of concrete so that internal vibration is not required in the slip‐

cast process. It has been found that the addition of small amounts of nanoclay can impart

both sufficient flowability and high green strength (shape stability) after slip‐casting. How

cement particles flocculate to gain strength immediately after casting is being studied using

tools such as focused laser beam reflection measurements.

Currently, no satisfactory method is available to monitor the strength of concrete after it is

cast. Sensors based on nuclear magnetic resonance, measurements of dielectric properties

at gigahertz frequency, and ultrasonic shear wave reflection are currently being studied. We

are using very high frequency ultrasonic shear waves to monitor the dynamic shear modulus

of elasticity of concrete immediately after it is cast. When concrete is liquid, it does not

transmit shear waves. However, as it solidifies, more and more shear waves are transmitted.

This shear wave reflection coefficient corresponds well with the measurements of

compressive strength. It appears that the relation between the coefficient and compressive

strength is linear and independent of the temperature of curing.

Concrete is a quasi‐brittle material. Macroscopic fracture is preceded by microcracks.

Conventional reinforcement can constrain macrocracks but does not interact with

microcracks. It has been shown that concrete reinforced with microfibers can substantially

increase the tensile strength of concrete, unlike conventional reinforcing. The next step is to


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reinforce cement with nanofibers so that the cement itself can be made ductile. Research

being conducted with carbon nanotubes will be presented.


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Addressing Erosion‐Related Distresses in Concrete Pavement Design

Dan G. Zollinger Texas A&M University, College Station, Texas, USA The consideration of erosion in concrete pavement design is deficient and distress

mechanisms related to erosion are the most significant observed under field conditions.

However, these distress mechanisms are the least considered in the design process. This

presentation will briefly review past and current design procedures with respect to erosion‐

related distresses, while elaborating on the relevance of the distress modes that are

addressed in design. This presentation will also briefly review testing for erosion and

address some rational approaches to simulate erosion‐related distress.


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Moving Beyond Empirical Models for Behavior of Early Age Concrete

David A. Lange University of Illinois at Urbana‐Champaign, Urbana, Illinois, USA Typical textbooks illustrate strength gain, modulus gain, shrinkage and creep as simple

curves as a function of time. The shapes of the curves will vary depending on mix

proportions, sources of constituents, temperature, and many other issues. The problem, of

course, is that such curves are not general. There is little one can do to predict the behavior

of a new material without a testing program to define its unique qualities. Over the past 10

years or so, researchers at the University of Illinois and elsewhere have made significant

progress in linking early behavior to more fundamental physical models. For example, a new

model for drying shrinkage utilizes capillary stress as the basic driving force and accounts for

creep deformation that occurs when a solid microstructure is under sustained stress ... and it

works. These kinds of physical models promise more robust insight into material behavior,

allowing material researchers to rationally think about the many parameters that contribute

to early age behavior.


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Experiences and Challenges for China’s Concrete Pavement Network

Bo Tian Research Institute of Highway, Beijing, China The first part of this presentation will provide an overview of concrete pavement usage in

China. This overview will include statistics such as total mileage of concrete pavements built

based on roadway classification as well as a background on temperature and latitude‐related

challenges in China. Chinese specifications for concrete pavement design and construction

will also be discussed including bending strength, thickness, and geometric standards. The

predominant challenges to the concrete pavement network in China include pumping,

faulting, and premature failures. In addition, techniques that are being employed to

overcome these challenges will also be addressed.

This presentation will also focus on the mechanical theory of concrete pavements as utilized

in China. The use of a solid foundation in modeling support conditions is viewed as

standard. This difference in modeling concrete pavements can provide distinct divergence in

the calculation of stresses from external loading and temperature from the standard Winkler

foundation model utilized in many parts of the world.


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Moisture Warping of Slabs on Grade

Will Hansen University of Michigan, Ann Arbor, Michigan, USA Moisture warping is the deformation of the slab surface profile due to a non‐uniform

moisture gradient (i.e. pore‐humidity gradient) between the top and the bottom. Typically,

the top surface is exposed to drying and thus shrinks more than the bottom. Consequently,

edges will tend to warp upward. Slabs on grade therefore can be expected to be in a

permanent upward edge warping condition. Autogenous shrinkage is another form of

moisture shrinkage. It is caused by self‐desiccation from cement hydration. Autogenous

shrinkage occurs without moisture loss to the surroundings, as opposed to drying shrinkage.

The pore‐humidity decreases uniformly within a cross section with increasing cement

hydration. Thus, no moisture warping develops as a result of self‐desiccation. Concretes

with water‐cement ratios less than about 0.70 are in a state of reduced pore‐humidity

during sealed curing. If a concrete slab is resting on a wet foundation, moisture uptake

within the bottom portion of the slab will result in a steep moisture gradient limited to about

75‐100mm due to pore‐discontinuity. Moisture gradients from surface drying and bottom

wetting work together to increase moisture warping uplift of slabs on grade.


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Potential Relative Humidity and Temperature Gradient Effects on Diamond‐Ground Concrete Pavements

Robert Rodden American Concrete Pavement Association, Skokie, Illinois, USA According to the FHWA, one of the advantages of diamond grinding is that a "smooth ride is

achieved by ... removing construction curling and moisture‐gradient warping of the slabs."

This advantage can be seen clearly in any diamond grinding project by comparing the pre‐

ground and immediately post‐ground profiles. There is, however, currently no consideration

for the relative humidity and temperature gradients in the slabs at the time of grinding and,

in some rare instances, unsatisfactory post‐ground behavior may be observed if the

pavement is diamond ground at a non‐optimal time. This presentation will discuss how a

"smoothening" of the surface to remove environmental gradients in one specific ambient

condition may result in a non‐smooth pavement once other ambient conditions are applied

to a diamond‐ground concrete pavement.


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Influence of Concrete Mixture and Admixture on Shrinkage

Ali Farhang Swedish Cement and Concrete Research Institute (CBI), SE‐ 100 44 Stockholm, Sweden

Limiting concrete drying shrinkage is an effective way of reducing the risk of shrinkage

cracking and therefore should be a number one priority when designing restrained concrete

structures such as industrial concrete floors and some types of concrete pavements.

Limitation of concrete drying shrinkage may be achieved by either reducing the external and

internal restraint and/or by lowering the amount of shrinkage. At the present time an on‐

going experimental research is under progress at Swedish Cement and Concrete Research

Institute (CBI) with focus on the influence of different mixtures and admixtures on concrete

shrinkage. The main aim of the research is to lower the amount of concrete shrinkage for a

typical concrete industrial floor with water‐cement‐ratio of 0.55 and a good workability.

In the first part of the laboratory tests, the influence of concrete mix design on shrinkage

was studied by testing different measures. One measure was to use different amount of

aggregate groups (0‐8 mm, 8‐16 mm and 16‐25 mm) with a total aggregate grading that

minimize the amount of paste in the mix. The other tested measures for minimizing

shrinkage were to use larger dmax, to reduce water demand, to reduce amount of fine

aggregates (particles under 0,63 mm), to wash the 0‐2 mm fractions, to replace 0‐2 mm

fractions with sand, and replacing some part of cement with fly ash. More than 20 different

concrete recipes were cast and the shrinkage developments were measured. Some of the

important findings will be presented during the Second Workshop on Advanced

Characterization, Modeling, and Design of Concrete Pavements.

In the next part of the laboratory tests, the some of concrete mix with lowest shrinkage will

be chosen and the additional effect of shrinkage reducing admixture (SRA) on shrinkage will

be studied. In addition to free shrinkage, restrained shrinkage, creep, elasticity modulus and

strength will be studied for chosen mixtures.


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Core‐Ring Model Analysis for Residual Stress in Concrete Beams

Xinkai Li Xiangshen Hou Songlin Ma Harbin Institute of Technology, Harbin, Nangang, P.R. of China It is impossible to know what the pavement strength is before knowing the residual stresses

in a concrete pavement. Core‐ring strain gage (CRSG) method was employed for measuring

residual stresses in concrete beams at Federal Aviation Administration’s (FAA’s) National

Airport Pavement Test Facility in 2007. CRSG method is similar to hole‐drilling strain‐gage

(HDSG) method popularly used for metal structures; however, it drills a “core‐ring” instead

of drilling a hole. Numerical analysis using ABAQUS with core‐ring and hole models are

conducted and comparisons of results are presented in this paper. And the results are also

compared with the results in FAA’s beam tests. It has been found that (1) the numerical

differences using the two models are insignificant and appear when the drilling depth is less

than 0.762cm (0.3 inch). When the drilling depth increases, the difference is negligible; (2)

the results calculated by both models are close to the measured ones by FAA. The results

indicate that 3D finite element procedure can well simulate the tests. Effects of three

parameters, core‐ring size, depth, and spacing to core‐ring edge on the released residual

stresses have been analyzed, and the numerical results provide significant information for

planning future tests.


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Characterizing the Fracture Behaviour of Ultra‐thin Continuously Reinforced Concrete Pavements (UTCRCP)

Erik Denneman CSIR Built Environment, Pretoria, South Africa Elsabe P. Kearsley Alex T. Visser University of Pretoria, South Africa Over the past years an innovative pavement system known as ultra‐thin continuously

reinforced concrete pavement (UTCRCP) has been developed and tested under the heavy

vehicle simulator (HVS) in South Africa. The test sections are around 50 mm in thickness and

contain significant amounts of steel fibres (80‐120 kg/m3). Plans to implement the system in

the rehabilitation of principal highways have reached a mature stage. Against this

background a need was identified to develop new fatigue damage models for this specific

type of material and application. Previous studies have shown the material to have a

significant ductile component in fracture as a result of the high quantities of steel fibres. The

ultimate goal is to develop a fracture mechanics based model for the prediction fatigue

failure of steel fibre reinforced concrete (SFRC) beams under dynamic loading. However, in

order to select a suitable fracture mechanics approach (i.e.: quasi‐brittle or plastic), the

behaviour of the beams under static loading had to be known. The test matrix included

Beams of various dimensions, as well as round panels tested in accordance with RILEM TC

50‐FMC and ASTM C 1550‐05 respectively. Two fibre contents were used and samples with

and without reinforcement bars were tested. The fracture behaviour of the tested material

is discussed in present paper.


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Experimental Validation of Computed Load‐Induced Deflections and Strains in Concrete Pavement Slabs

Kitti Manokhoon Mang Tia University of Florida, Gainesville, Florida, USA Bouzid Choubane Michael Bergin Florida Department of Transportation, Gainesville, Florida, USA Full‐scale instrumented concrete slabs were constructed and tested by means of a Heavy

Vehicle Simulator (HVS) to study the behavior of concrete replacement slabs at early age and

the effects of concrete properties on the performance of the replacement slabs. The test

slabs were modeled by a finite element model, FEACONS, which considers the effects of the

temperature differential in the slabs as well as the effects of the applied load, elastic

modulus and coefficient of thermal expansion of concrete, slab thickness, joint

characteristics and effective subgrade stiffness. The model used was calibrated by back‐

calculations using Falling Weight Deflection (FWD) data, and also by comparing the

computed strains with the measured strains from embedded strain gages in the test slabs.

The results of the study show that the calibrated FEACONS model was able to predict the

load and temperature induced deflections and strains in the concrete slabs well, and can be

used to analyze the behavior of concrete replacement slabs.


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Selected Results in Mechanics of Concrete and Concrete Structures Obtained under Supervision of Prof. V.D. Kharlab

Lev Kagan‐Rozentsveyg St. Petersburg State University of Architecture and Civil Engineering, St. Petersburg, Russia The presentation will begin with a brief overview of 50 years of research activities in the

areas of concrete creep, shrinkage, and fracture performed under supervision of professor

Kharlab at the St.‐Petersburg University of Architecture and Civil Engineering. The following

three topics will be considered in more detail: creep analysis of aging growing structures;

modeling of concrete creep behavior at very early ages; and gradient strength analysis.

A general theory of viscoelastic behavior for homogeneous aging structures changing its

geometry under loading (growing structures) was developed by Prof. Kharlab in 1960s. An

elastic‐viscoelastic corresponding principle was derived for these types of structures.

One of the applications of the general theory of growing structures was the development of

a model describing concrete creep at early age. The model treats concrete as a porous

composite material with pores continuously filled up (internal growth). The inputs of the

model include the modulus of elasticity curve at early age and the creep compliance at a

sufficiently large age when extensive aging is completed (for example, 28‐day old concrete).

These inputs are relatively easy to measure in the lab. Using these inputs, the model can

predict the creep compliance and creep Poisson’s ratio at any age.

Finally, development of a singular failure criterion for quasi‐brittle materials is presented.

This criterion utilizes the stress state obtained from the linear elastic analysis and is able to

account for non‐uniformity of the stress state on strength and evaluate strength at points

with singular stress states. An application of this criterion for the stress states obtained for

classical boundary value problems is presented. It is shown that for the analysis of small

cracks in infinite bodies the proposed criterion offers an improvement compared to the

linear elastic fracture mechanics (LEFM) criterion.


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Characterization and Impact of Built‐in Curling on Rigid Pavement Response

Jacob E. Hiller Michigan Technological University, Houghton, Michigan, USA

For over half a century, researchers and practitioners have noted a permanent curl to

concrete in slabs‐on‐grade and jointed pavement applications. This “built‐in curling”

phenomenon can be affected by factors such as construction temperature conditions, curing

methods, concrete mix design, slab geometry, support conditions, and restraint of the slab,

among others. Built‐in curling can have a profound effect on both ride quality and stress

development that has gone unaccounted for until recent mechanistic‐empirical analysis

procedures such as the Mechanistic‐Empirical Pavement Design Guide and RadiCAL. While

built‐in curling mechanisms tend to be relatively permanent after early‐age creep effects

have dissipated in concrete, this level of curl works in conjunction with cyclical temperature

curling and moisture warping mechanisms to produce the total measureable level of curl in

concrete slabs. This total amount of curl can result in a loss of support in the corners of the

slabs even in the most extreme daytime temperature profile conditions, thereby increasing

stresses from external loading and introducing axle spacing as a critical factor in top‐down

fatigue crack development. This change in fundamental assumptions of stress development

in concrete pavements can affect both the timing and location of fatigue damage in concrete

pavements. This presentation aims to look at both fixed and controllable factors that affect

built‐in curling as well as what design parameters can be chosen to help influence both the

timing and the fatigue cracking mechanism when failure does occur in jointed concrete

pavements.


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Indications of the Effect of Coefficient of Thermal Expansion on Cracking of Jointed Concrete Pavements

Erwin R. Kohler Dynatest Consulting, Inc., Davis, California, USA The influence of the coefficient of thermal expansion (CTE) on cracking of jointed concrete

pavements is investigated in this study, based on crack survey data and laboratory

evaluation of samples from approximately one hundred sections of in‐service highway

pavements throughout the state of California. The CTE values found in the experiment

ranges from 4.8 to 6.7 microstrain/°F. The sections’ cracking data was obtained from the

Caltrans pavement management database, and consisted of first stage cracking, third stage

cracking, and corner cracking. Condition data for sections up to 46 years old was included.

Taking into account the slabs on all traffic lanes of all sections and the time histories of

cracking data, the number of cases investigated in the study exceeded 3,400. It was found

that CTE does affect crack development on jointed concrete pavements. Despite the

difficulties of subjective cracking data, the pavements with CTE higher than 5.7

microstrain/°F showed more cracking that those with CTE lower than this value


28

Consideration of Environmental Effects in the Backcalculation of Jointed Plain Concrete Pavement Layer Moduli and the Associated Challenges

Mustafa Birkan Bayrak Halil Ceylan Iowa State University, Ames, Iowa, USA Falling Weight Deflectometer (FWD) tests are conducted on concrete pavement systems to

assess the in‐situ structural capacity of pavement, evaluate joint load transfer efficiency, and

to identify voids under joints. In order to evaluate the structural condition of in‐service

concrete pavements and to characterize the layer properties as inputs into available

numerical or analytical programs, backcalculation of pavement properties from FWD test

data is a useful tool. The elastic modulus of the slab (EPCC) and the coefficient of subgrade

reaction (ks) are the backcalculated layer moduli parameters for Jointed Plain Concrete (JPC)

pavement systems.

It is known that the environmental conditions during the time of FWD testing have an

influence on the final backcalculation analysis results. Especially the Temperature Gradient

(TG) through concrete slab thickness results in slab deformation (typically referred to as slab

curling) which affects the deflection basin measured during the FWD tests. Therefore,

backcalculated moduli of pavement layers based on flat‐slab condition assumptions may be

unrealistic. The first step towards resolving this challenging problem is to predict the Total

Effective Linear Temperature Difference (TELTD).

The objective of this investigation is to develop a rapid methodology for backcalculating the

TELTD in JPC pavement systems from the FWD deflection basins and the thickness of the

concrete slab. With additional tests in the field, it may also be possible to estimate the

Effective Built‐In Temperature Difference (EBITD) which is an important component of any

mechanistic‐empirical design procedure for JPC pavements.


29

The results of this study demonstrated that trained Neural Networks (NN) based models

have the potential to successfully predict the TELTD of in‐service pavements in an efficient

and cost‐effective way without any need for embedded instrumentations in concrete

pavements. Therefore, such NN‐based backcalculation models can be used for large number

of concrete slabs in a relatively short period of time for estimating the TELTD that can be

used for adjustments for the in‐situ structural capacity of JPC pavement systems. There

needs to be a comprehensive FWD testing program and related field investigation to further

validate the findings of this study.


30

Failure Model Improvement for PCC Pavements

Edward Guo SRA International, Atlantic City, New Jersey, USA The definition of structural failure model is proposed for differentiating it from the

pavement design model. Three failure stages are clearly defined: initiation of the first crack,

crack development to full depth and length, and pavement failed to provide expected

service. The three failure stages have been observed at the FAA’s National Airport Pavement

Test Facility and are presented in this workshop. The key parameter, �/MR (Critical stress /

specimen strength), seems insufficient to describe and understand the failure mechanism of

a concrete pavement. How to improve the existing failure model? Pending questions are

provided for discussion in the workshop.


31

Durable Construction by Help of a Semi‐Probabilistic System and Differentiated Inputs into Thickness Design

Stephan Villaret Villaret Ingenieurgesellschaft mbH, Frankfurt, Germany This report doesn’t deal with all the influences on durability of concrete pavements, but only

with thickness design to avoid cracks and the most important inputs into it. It is shown that a

semi‐probabilistic method is the most complex one today. By help of this it is possible to

consider all deciding properties each for itself with a certain statistical safety – so that an

overall factor of safety must not be applied. Rather for roads certain (limited) failure rates

during lifetime may be allowed.

The author accentuates the need for input correctly investigated structural and material

properties into dimensioning. So he gives reasons for use of the tensile split strength –

determined by correctly defined guidelines ‐ as no concrete pavement fails at low

compressive strength, but of low tensile split strength. Thus cracks begin from upside or

underside of the concrete pavement.

Thickness results, designed by program AWDSTAKO in dependence of strength, slab length

and width as well as the number of equivalent loads are shown. Last but not least it is shown

that it isn’t possible to allow a failure rate of 100 or 40 % on lifetime end, in these cases after

the half time 70 to 80 % of the slabs would fail. This is why the run of the fatigue curves is

not linear. Therefore only failure rates of 5 to 10 % should be used at calculation.


32

A Framework using DAKOTA and MEPDG for the Probabilistic Analysis of Pavements

Steven F. Wojtkiewicz University of Minnesota, Minneapolis, Minnesota, USA This work describes the development of a software framework combining two pre‐existing

software packages, the Mechanistic‐Empirical Pavement Design Guide (ME‐PDG) and Design

Analysis Kit for Optimization and Terascale Applications (DAKOTA), to facilitate the

probabilistic analysis of pavements. The overarching goal of this study is to gain deeper

insight into the design of rigid and flexible pavements, thereby leading to better pavement

designs. ME‐PDG is a design tool which predicts the reliabilities and distresses in various

pavement characteristics such as cracking, rutting, joint faulting etc. over the design life of

the pavement, based upon a given set of design parameters (layer thicknesses, concrete

strength etc.). However, a large number of input sample sets must be considered to

determine what, if any, statistical relationships can be drawn between the input and the

output variability. DAKOTA is a toolkit developed to facilitate rapid, systematic probabilistic

studies using study‐specific simulator models (ME‐PDG in this study). DAKOTA allows

analysts to efficiently execute iterative analyses of the simulator model including parametric

studies, design of computer experiments, uncertainty quantification and optimization. This

presentation will provide an overview of the architecture of the developed software

framework and discuss the challenges encountered in its implementation. The framework

was utilized to perform a probabilistic, parametric study of a rigid pavement design. The

study consisted of 300 random sets of design input data (asphalt concrete thickness, 28‐day

PCC compressive strength, initial IRI, joint spacing, loss of full friction). Results from this

statistical analysis of the variations in the predictions of distress values for terminal IRI,

transverse cracking and mean joint faulting will be presented.


33

Calibration of MEPDG Cracking Models

John T. Harvey University of California‐Davis, Davis, California, USA The University of California Pavement Research Center (UCPRC) team (UC Davis, UC

Berkeley, Dynatest Consulting) has been working with the California Department of

Transportation to validate, calibrate and implement mechanistic‐empirical design

procedures and design tools based on ME design procedures for rigid pavements. The

discussion will briefly present the results of this work, the questions raised, and the

unresolved and partially resolved answers. Questions measurement, estimation and effects

of surface albedo, long‐term slab warping due to differential drying shrinkage, CTE and

flexural strength. The most important effect to be discussed, which dominated the

calibration process was friction between base and slab. This project has exclusively focused

on plain jointed concrete pavement, nearly all built without dowels.


34

Mechanistic Modeling of Pavement Performance for Pavement Design

H. Thomas Yu Federal Highway Administration, McLean, Virginia, USA In developing Mechanistic Empirical Pavement Design Guide (MEPDG), efforts were made to

refine the mechanistic modeling process to the extent possible using the available

technology. The state of the technology at the time was such that significant refinements

were possible, even compared to the time of NCHRP Project 1‐26, the previous attempt at

ME pavement design completed in 1990. For example, ESALS were replaced with the load

spectra data, environmental effects are modeled using hourly climatic data, and the effects

of material properties, as well as the effects of changes in material properties over time

were modeled. Pavement performance predicted using the MEPDG models can be very

sensitive to several of the input parameters, including climate (weather station), material

properties, and various traffic inputs. However, both the ability to predict some of the

design inputs (such as hourly weather condition and axle load distribution) to such detail and

the need for such detailed data are in question. Given the uncertainties involved, it is

possible that some average input (e.g., monthly‐average, hourly temperatures; and regional‐

average axle load distribution) may better characterize the local conditions and are more

appropriate for use in pavement design.


35

Implementation of Fatigue Models for the Design of Concrete Pavements in Brazil

José Balbo University of Sáo Paulo, Sáo Paulo, Brazil Portland cement concrete has been used for pavement construction in Brazil since the end

of the first quarter of last century for highways, harbor terminals, airport aprons and even

for buses corridors and industrial floors, and recently, the interests for such a paving

material increased. Results of a laboratorial investigation of fatigue resistance of high

strength concrete (HSC) for paving are presented herein, employing a mixture of raw

materials from São Paulo area. Simulation of the HSC fatigue model is done in order to

compare changes in slab thickness when using the PCA‐84 design criteria. Received data

suggests the need for searching specific models for local materials instead of using former

laboratorial derivate equations for design.


36

Flexural Capacity of Concrete Slabs

Jeffery R. Roesler Cristian Gaedicke

University of Illinois at Urbana‐Champaign, Urbana, Illinois, USA The fatigue life prediction of concrete slabs has traditionally been based calculation of the

ratio of the critical tensile stress to the beam flexural strength, which is then related to the

number of allowable load applications to failure. Fatigue curves have been developed over

the years to relate the stress ratio to the load cycles to failure from laboratory beam fatigue

testing, laboratory slab testing, accelerated pavement testing, and field performance

observations. It has been shown through laboratory and field tests that the flexural strength

of the concrete based on the simply supported beam test is not an accurate representation

of the strength of concrete slabs. A new approach to calculate the flexural load capacity of

concrete slabs is proposed to enable consideration of the geometry and concrete material

dependent load capacity of concrete pavements. This new approach uses a 3‐D finite

element simulation of a concrete slab with cohesive elements. The constitutive relationship

for the cohesive zone model is defined from experimental fracture parameters based on

single edge notched beam tests.


37

NAPTF Unbonded Concrete Overlay Testing: Challenges and Issues in Materials Characterization

Shelley M. Stoffels Pennsylvania State University, State College, Pennsylvania, USA Full scale testing of unbonded concrete overlays was conducted at the NAPTF in two

experimental stages. Construction of the first stage included the initial underlay pavement

in three thicknesses, an asphalt concrete interlayer, and the construction of the overlay in

three thicknesses. The thickest overlay was placed on the thinnest underlay, resulting in

three ratios of overlay to underlay thickness. Each of the three structural cross‐sections was

divided into two test items, one loaded with a dual tandem and one with a triple dual

tandem gear. All test items were loaded to failure, and the overlay and interlayer removed.

After inspection of the underlay and load‐inducement of further distress, the interlayer and

overlay were reconstructed. The loading was then repeated, but at a lower wheel load to

compensate for the deteriorated underlay.

During both stages of construction, conventional quality control volumetric and strength

testing of the materials was conducted. The concrete strengths achieved were substantially

less than expected, perhaps due to the cold weather construction. During the second stage

of overlay construction, the mix design was changed, reducing the percentage of flyash.

However, the flexural strength was not substantially increased. For the second overlay,

fracture characterization of the mix both before and after loading was also performed. The

results of the fracture characterization, in tandem with the conventional testing, will be

presented during this workshop. Discussion will be requested of possible implications and

uses of the data. In addition, interlayer material has been retained and is available for

testing. The planned testing program will also be discussed, in the context of desired

modeling inputs and relationships to instrumentation responses.


38

Laboratory and Finite Element Modeling of Joint Lockup

Lev Khazanovich University of Minnesota, Minneapolis, Minnesota, USA Transverse joints allow for the expansion and contraction of the concrete layer in portland

cement concrete (PCC) pavements due to temperature and moisture variations. Dowels are

used in these joints to improve load transfer capacity across the joint in order to reduce slab

deflections and stresses. However, the ability of the concrete to expand and contract at the

joint may be restrained, resulting in joint lockup. Joint lockup has been attributed to

rotational misalignments of the dowels in the past. The results of this study indicate that

other factors may have a greater effect on joint opening behavior. It was found from the

laboratory testing that lack of proper greasing significantly increased the dowel pullout

force. It was also observed from the laboratory testing that properly greased dowels with

rotational misalignment exhibited similar pullout forces when compared to aligned dowels.

Finite element modeling identified dowel‐concrete friction as a very important parameter

that controls the joint behavior. High friction may cause damage in concrete causing

distresses like joint spalling and cracking near joints, which has been traditionally attributed

to rotational misalignment of the dowel. This suggests the importance of ensuring proper

bond breaking between dowel and concrete.

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