Calibration of Rutting Models for Structural and Mix Design (2012)

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N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP REPORT 719 Calibration of Rutting Models for Structural and Mix Design Harold L. Von Quintus Applied ReseARch AssociAtes, inc. Round Rock, Texas Jagannath Mallela Applied ReseARch AssociAtes, inc. Round Rock, Texas Ramon Bonaquist AdvAnced AsphAlt technologies, llc Sterling, Virginia Charles W. Schwartz UniveRsity of MARylAnd College Park, Maryland Regis L. Carvalho dynAtest consUlting, inc. Upper Marlboro, Maryland Subscriber Categories Highways • Materials • Design TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2012 www.TRB.org  Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration

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C O O P E R A T I V E R E S E A R C H P R O G R A M S CRP STAFF FOR NCHRP REPORT 719 Christopher W. Jenks, Director, Cooperative Research Programs Crawford F. Jencks, Deputy Director, Cooperative Research Programs Edward T. Harrigan, Senior Program Officer Anthony Avery, Senior Program Assistant Eileen P. Delaney, Director of Publications Doug English, Editor NCHRP PROJECT 9-30A PANEL Field of Materials and Construction—Area of Bituminous Materials Carl L. Monismith, University of California – Berkeley, Berkeley, CA (Chair) Bouzid Choubane, Florida DOT, Gainesville, FL Shongtao Dai, Minnesota DOT, Maplewood, MN Danny A. Dawood, The Transtec Group, Mechanicsburg, PA Adam J. T. Hand, Granite Construction, Inc., Sparks, NV Julie E. Kliewer, Arizona DOT – Phoenix Construction Division, Phoenix, AZ Leslie Ann McCarthy, Villanova University, Villanova, PA David E. Newcomb, Texas Transportation Institute, College Station, TX Murari M. Pradhan, Arizona DOT, Phoenix, AZ John Bukowski, FHWA Liaison Katherine A. Petros, FHWA Liaison Nelson H. Gibson, FHWA Liaison Frederick Hejl, TRB Liaison

F O R E W O R D This report proposes revisions to the Mechanistic–Empirical Pavement Design Guide (MEPDG) and software to (1) incorporate three alternative rut-depth prediction models that rely on repeated load (triaxial) permanent deformation or constant height testing to provide the requisite input data, and (2) provide revised coefficients for the original and alternative rut-depth transfer functions or prediction models derived from material proper- ties measured in the laboratory and pavement performance data. Thus, the report will be of immediate interest to engineers in public- and private-sector organizations with responsi- bility for the structural design and analysis of asphalt concrete (AC) pavements. NCHRP Project 9-30A, “Calibration of Rutting Models for HMA Structural and Mix Design,” was conducted by Applied Research Associates, Inc. (ARA), Round Rock, Texas, with major participation by Advanced Asphalt Technologies, LLC, Sterling, Virginia, and the University of Maryland, College Park, Maryland. The objective of this research was to recalibrate the AC rutting prediction model in the MEPDG software developed in NCHRP Projects 1-37A and 1-40 with measured material properties and performance data from Long-Term Pavement Performance Program Special Pavement Studies (LTPP SPS) and other full-scale pavement sections, including sections built with modified asphalt binders. The measured material properties included volumet- ric properties, dynamic modulus, and repeated-load plastic deformation tests (triaxial and shear-based tests). In addition, the project team evaluated three alternative rut-depth trans- fer functions, programmed them into the MEPDG Version 1.0, and compared the accuracy and goodness of fit of their predicted rut depth results to those obtained with the original (Kaloush) transfer function developed in NCHRP Projects 1-37A and 1-40. Material properties needed for Input Level 1 were measured on original materials and pavement cores from 45 AC pavement sections from the LTPP SPS-5, SPS-6, and SPS-9, the WesTrack project, the NCAT test track, MnROAD, and I-710 in Long Beach, Califor- nia. Pavement rutting distress data in the LTPP and other databases were supplemented by forensic examination (including trenching) of pavement sections. The data from these pavement sections were used for recalibration and validation of the original and three alternative rut-depth transfer functions: 1. Asphalt Institute (modified Leahy) vertical strain and deviator stress transfer function. 2. Verstraeten deviator stress transfer function. 3. WesTrack shear strain and stress transfer function. By Edward T. Harrigan Staff Officer Transportation Research Board

A key characteristic of these alternative transfer functions is that they use repeated-load (triaxial) permanent deformation or constant height shear testing to develop the MEPDG input data, in contrast to the original MEPDG transfer function that only requires dynamic modulus (stiffness) mixture testing for Input Level 1. The research reached several key conclusions. With proper calibration, all four transfer functions accurately simulated the evolution of AC pavement rutting, and there were no statistically or practically significant differences among results obtained with the four func- tions. All of the transfer functions were calibrated to provide reasonable predictions of rut depth. Finally, for higher traffic conditions and larger rut-depth threshold values or design criteria, conducting repeated load tests to define the plastic deformation properties of AC mixtures is cost effective. The four transfer functions are implemented in the software program MEPDG Version NCHRP 9-30A produced as a project deliverable. MEPDG Version NCHRP 9-30A is based on MEPDG Version 1.0 produced in NCHRP Project 1-40 and allows the user to choose among the four transfer functions for predicting the rutting behavior of an AC pavement design. All transfer function calibration coefficients are derived from the calibration carried out in the project with measured material properties. Other enhancements or modifications made in MEPDG Version NCHRP 9-30A include (1) the capability to enter mixture- or layer-specific permanent deformation parameters, (2) a fix to the local calibration param- eter for unbound aggregate base layers, and (3) incorporation of a normal distribution of truck traffic rather than a uniform distribution between limits of truck wander. The report fully documents the research leading to MEPDG Version NCHRP 9-30A, and includes six appendixes: • Appendix A: Proposed Addendum to AASHTO Publication MEPDG-1: Mechanistic– Empirical Pavement Design Guide, Interim Edition: A Manual of Practice • Appendix B: Software Modifications or Alterations to the MEPDG for Predicting Rut Depths • Appendix C: Step-By-Step Procedure for Adjusting the Global Calibration Parameters of the MEPDG (Kaloush) Rut-Depth Transfer Function • Appendix D: Dynamic Modulus Test Results • Appendix E: Repeated-Load Test Results • Appendix F: Incremental Benefit–Cost Analysis: Comparison of Alternate Transfer Func- tions and Test Methods In addition, five appendixes are available for download from the NCHRP Project 9-30A web page at http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=965: • Appendix G: December 2005 Facilitated Workshop: Executive Summary and Minutes • Appendix H: User Manual for the M-E_DPM Database • Appendix I: Simple Performance Test System Instrumentation • Appendix J: Summary of Data from the Test Sections Used For the Calibration and Vali- dation of MEPDG Version NCHRP 9-30A • Appendix K: Advanced Materials Characterization and Modeling The software program MEPDG Version NCHRP 9-30A was provided to the AASHTO Joint Task Force on Pavements and the DARWin-ME Task Force for consideration for adop- tion in a future version of DARWin-ME.

C O N T E N T S 1 Chapter 1  Introduction  1 1.1 Background 2 1.2 Research Objective 2 1.3 Project Overview 2 1.4 Scope of Report and Project Documentation 3 1.5 Lessons Learned 6 Chapter 2  Summary of Findings 6 2.1 Mechanistic–Empirical Rut-Depth Transfer Functions 6 2.1.1 Facilitated Workshop on Rut-Depth Transfer Functions 7 2.1.2 Rut-Depth Transfer Functions 10 2.2 Improvements and Enhancements: MEPDG Software Version 9-30A 11 2.2.1 Additional Rut-Depth Transfer Functions 13 2.2.2 HMA Layer-Specific Plastic Deformation Coefficients 14 2.2.3 Depth Function Enhancement 17 2.2.4 Plastic Deformation Coefficients for Unbound Layers 17 2.2.5 Lateral Wander Effects 18 2.3 Data Storage 19 2.4 Experimental Plan for Calibration and Assessment of Rut-Depth Transfer Functions 19 2.4.1 Experimental Approach 20 2.4.2 Hypotheses and Assumptions 21 2.4.3 Experimental Design 23 2.4.4 Pavement Types and Rehabilitation Strategies 25 2.4.5 Types of Test Sections 27 2.4.6 Number of Test Sections for Calibrating Rut-Depth Transfer Functions 28 2.4.7 Criteria for Project Selection 28 2.4.8 Projects Included in Sampling Template 29 2.5 Preliminary Analysis of Test Sections and HMA Mixtures 29 2.5.1 Site Features and Layer Properties 34 2.5.2 Field-Derived Plastic Deformation Coefficients 36 2.5.3 Forensic Investigations 40 2.6 Exploratory Test Program 40 2.6.1 Instrumentation Study 42 2.6.2 Stress State for Plastic Deformation Testing 44 2.6.3 Temperature for Plastic Deformation Testing 45 2.6.4 Exploratory Test Program: Defining Test Conditions 54 2.6.5 Repeated-Load Constant-Height Shear Test Program 55 2.7 Analysis of Repeated-Load Plastic Deformation Test Data 55 2.7.1 Repeated-Load Triaxial/Flow Number Test 59 2.7.2 Repeated-Load Constant-Height Shear Tests 59 2.7.3 Summary

60 2.8 Laboratory Production Test Program 61 2.8.1 Types of Samples for Testing 62 2.8.2 Asphalt Physical Property Tests 62 2.8.3 HMA Mixture Design 62 2.8.4 Test Specimen Preparation 65 2.8.5 Testing of HMA Mixtures 69 2.9 Determination of Laboratory-Measured Plastic Strain Coefficients 69 2.9.1 Slope of Secondary Region: Exponent for Number of Load Cycles 75 2.9.2 Temperature Exponent: Effect on Intercept from Secondary Region 75 2.9.3 Intercept from Secondary Region: Equivalent Annual Temperature 76 2.9.4 Reconstituted Mixture Test Specimens 81 2.9.5 Field Cores 83 Chapter 3  Data Interpretation and Application 83 3.1 Verification of Transfer Functions with Global Calibration Coefficients 83 3.1.1 Global Default Values: Input Level 3 91 3.1.2 Dynamic Modulus 92 3.1.3 Summary: Redefining the Input Levels 93 3.2 Calibration and Validation of Laboratory-Derived Transfer Functions: Input Level 1 94 3.2.1 Rut-Depth Measurement Error 94 3.2.2 Unbound Layers 95 3.2.3 HMA Transfer Function Parameters 103 3.2.4 Adjustment of Laboratory-Derived Values 106 3.2.5 Precision and Accuracy of Transfer Functions 110 3.2.6 Validation of Field-Adjusted Laboratory-Derived Plastic Strain Values 111 3.3 Mixture Volumetric Adjustment Factors: Input Level 2 111 3.3.1 Intercept of Transfer Functions 112 3.3.2 Temperature Term Exponent of Kaloush Transfer Function 112 3.3.3 m-Value or N-Term Exponent of Transfer Functions 113 3.3.4 Comparison of Predicted (Input Level 2) and Measured Rut Depths 113 3.4 Assessment and Effectiveness of Rut-Depth Transfer Functions 113 3.4.1 Accuracy and Precision of Transfer Functions 114 3.4.2 Benefit–Cost Analysis 115 3.4.3 Hypothesis Evaluation 117 3.4.4 Other Factors or Observations 118 3.5 Application: Mixture Design and Acceptance 119 3.6 Advanced Mixture Characterization and Rut-Depth Simulation Models 121 3.6.1 Advanced Mixture Characterization Tests 121 3.6.2 Model Formulation 123 Chapter 4   Conclusions and Proposals for Implementation  and Future Research 123 4.1 Conclusions 124 4.2 Proposals for Implementation and Future Research 126 Appendix A   Proposed Addendum to AASHTO Publication  MEPDG-1: Mechanistic–Empirical Pavement Design Guide, Interim Edition: A Manual of Practice

142 Appendix B   Software Modifications or Alterations to  the MEPDG for Predicting Rut Depths 151 Appendix C   Step-by-Step Procedure for Adjusting  the Global Calibration Parameters of the MEPDG (Kaloush) Rut-Depth Transfer Function 154 Appendix D  Dynamic Modulus Test Results 163 Appendix E  Repeated-Load Test Results 186 Appendix F   Incremental Benefit–Cost Analysis:  Comparison of Alternate Transfer Functions and Test Methods Appendices G through K are available to download from the NCHRP Project 9-30A web page at http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=965. 204 Cited AASHTO Standard and Provisional Practices  and Methods of Test 205 References Note: Many of the photographs, figures, and tables in this report have been converted from color to grayscale for printing. The electronic version of the report (posted on the Web at www.trb.org) retains the color versions.

AUTHOR ACKNOWLEDGMENTS The research described herein was performed under NCHRP Project 9-30A by the transportation sector of Applied Research Associates (ARA), Inc. Mr. Harold L. Von Quintus served as the Principal Investigator on the project. Mr. Von Quintus was assisted by Mr. Jagannath Mallela as the project manager and engineer on the team. Other management team members and subcontractors included Dr. Charles W. Schwartz, P.E., of the University of Maryland, and Dr. Ramon Bonaquist of Advanced Asphalt Technologies, LCC. Both Dr. Schwartz and Dr. Bonaquist served as Co-Principal Investigators on the project. In addition, the project management team was supported by many individuals who assisted in the facilitated workshop, software modifications, computational analyses, laboratory testing, field forensic investigations, calibration, and other activities. These individuals are listed as follows: Applied Research Associates: Dr. Chetana Rao assisted with preparation of the workshop and analysis of the transfer functions. Dr. Alex Gotlif and Dr. Greg Larson were the individuals that made all revisions and upgrades to the software. Mr. Leslie Titus-Glover, Mr. Mark Stanley, and Dr. Suri Sadasivam partici- pated in the data analysis activities and exported data from the Long Term Pavement Performance (LTPP) database for use in the calibration effort. Dr. Chetana Rao, Mr. Ajay Singh, and Mr. Brandon Von Quintus assisted with the local calibration and analysis of the rut-depth transfer functions. Mr. Paul Littleton par- ticipated as a member of the forensic investigation team. Ms. Robin Jones provided editorial review and report formatting. University of Maryland: Dr. Laura Scott participated as the facilitator for the workshop. Dr. Regis L. Carvalho (now with ARA) assisted with conducting the facilitated workshop, developing and popu- lating the Mechanistic–Empirical Distress Prediction Model (M-E_DPM) database, and developing the advanced mixture characterization tools, procedures, and software. The advanced materials characteriza- tion and modeling effect were completed under the supervision of Dr. Charles W. Schwartz. The University of Maryland completed all of the advanced modeling activities. Advanced Asphalt Technologies (AAT): All of the laboratory testing was completed under the super- vision of Dr. Ramon Bonaquist. AAT’s laboratory technician provided all of the production testing con- ducted under this project. North Carolina State University: Dr. Richard Kim assisted in the advanced mixtures characterization studies for the project. Arizona State University: Dr. Mohamed El Basyouny participated as an independent reviewer of the software modifications made to the Mechanistic–Empirical Pavement Design Guide. Burns Cooley Dennis, Inc.: Mr. Robert Long participated as a member of the forensic investigation team. One of the major efforts of this study was the facilitated workshop in selecting the rut-depth transfer functions that were to be calibrated and evaluated under Phase III. The team greatly appreciates the time attendees of the workshop spent planning for and attending the workshop. Individuals that participated in this workshop, other than the team members, included Dr. Carl L. Monismith and Mrs. Lorina Popescu with the University of California at Berkeley (Ms. Popescu assisted the team with conducting the workshop and preparation of the meeting minutes); John Bukowski, Katherine A. Petros, and Cheryl Richter with the FHWA; Julie E. Kliewer and Murari M. Pradhan with the Arizona DOT; Dr. Steve Brown (consultant); Leslie Ann McCarthy (Villanova University); Bouzid Choubane (Florida DOT); Shongtao Dai (Minnesota DOT); Danny A. Dawood (the Transtec Group); Adam J. T. Hand (Granite Construction, Inc.); John Haddock (Purdue University); Shmuel Weissman (University of California at Berkeley); Tom Scarpas (Delft University); Per Ullitz (Dynatest); Rey Roque (University of Florida); Linbing Wang (Virginia Tech); and Mohamed El Basyouny (Arizona State University). The project team also appreciates and acknowledges the support and technical assistance of various agency and contractor personnel that provided field and laboratory data and support for the forensic investigations of multiple test sections included within this study. Those individuals involved in coordina- tion and data collection for specific test sections are listed in the following.

LTPP – MRL: Dr. Sirus Alavi with Transportation Engineers (contractor on the LTPP program) for coordinating, scheduling, and shipping component materials from the LTPP Materials Research Library in Reno, Nevada. These materials were used in the production test program for calibrating the different transfer functions considered and evaluated within the study. National Center for Asphalt Technology (NCAT): Drs. Nam Tran and Buzz Powell with NCAT for providing measured rut depths and samples of the hot-mix asphalt mixtures placed on specific test sec- tions at the NCAT test track. Arizona: Ms. Judie Kliewer with the Arizona Department and Mr. Kevin Senn with Nichols Consult- ing for providing access to and assistance with the forensic investigation of Arizona’s LTPP SPS-5 project. Mississippi: Mr. William Barstis with the Mississippi Department of Transportation and Mr. Gaylon Baumgardner with Paragon Technical Services, Inc., for providing information and additional materials used on Mississippi’s LTPP SPS-5 project. Missouri: Mr. John Donahue with the Missouri Department of Transportation for providing materials and mixture design information for Missouri’s LTPP SPS-5 project. Montana: Ms. Sue Sillick and Mr. Jon Watson with the Montana Department of Transportation for providing materials, mixture data, and access to Montana’s LTPP SPS-5, SPS-1, and SPS-9 projects. Texas: Dr. Fee Fong with the Texas Transportation Institute for assisting with the coordination of the forensic investigation of the Texas SPS-5 project. Wisconsin: Mr. Steve Krebs and Mrs. Laura Fenley with the Wisconsin Department of Transportation for providing mixture design information and assistance with trenching the Wisconsin SPS-1 and SPS-9 LTPP projects. Dr. Erv Dukatz with Mathy Construction provided additional samples of the fine and coarse aggregate that were used in production to complete the production test program for the Wisconsin projects.