A Performance-Related Specification for Hot-Mixed Asphalt (2011)

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TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2011 www.TRB.org 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 704 Subscriber Categories Highways • Materials • Construction A Performance-Related Specification for Hot-Mixed Asphalt FUGRO CONSULTANTS INC. Austin, TX ARIZONA STATE UNIVERSITY Tempe, AZ Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration

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CRP STAFF FOR NCHRP REPORT 704 Christopher W. Jenks, Director, Cooperative Research Programs Crawford F. Jencks, Deputy Director, Cooperative Research Programs Edward T. Harrigan, Senior Program Officer Melanie Adcock, Senior Program Assistant Eileen P. Delaney, Director of Publications Margaret B. Hagood, Editor NCHRP PROJECT 09-22 PANEL Field of Materials and Construction—Area of Bituminous Materials Larry L. Michael, Hagerstown, MD (Chair) Dale S. Decker, Dale S. Decker, LLC, Eagle, CO James P. Delton, Arizona DOT, Phoenix, AZ Stacey D. Diefenderfer, Virginia DOT, Charlottesville, VA W. M. “Mike” Lackey, Topeka, KS Rebecca S. McDaniel, Purdue University, West Lafayette, IN David E. Newcomb, National Asphalt Pavement Association, Lanham, MD Charles F. Potts, Heritage Group, Indianapolis, IN Ronald A. Sines, Oldcastle Materials, Leominster, MA James M. Warren, Asphalt Contractors Association of Florida, Inc., Tallahassee, FL Dean C. Weitzel, MACTEC Engineering & Consulting, Inc., Reno, NV John D’Angelo, D’Angelo Consulting, LLC, Annandale, VA Michael R. Smith, FHWA Liaison Frederick Hejl, TRB Liaison 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

This report provides a proposed performance-related specification (PRS) for hot-mix asphalt (HMA) in the form of the Microsoft Windows®-based Quality-Related Specification Software (QRSS). The report details the research performed and illustrates the development of the QRSS and its ability to carry out pay adjustment factor and payment computations by comparing the as-built pavement performance with that of the as-designed pavement. Thus, the report will be of immediate interest to staff of state highway agencies, materials suppliers, and paving contractors with responsibility for specification and construction of HMA pavements. NCHRP Project 9-22, “Beta Testing and Validation of HMA PRS,” was awarded to Fugro Consultants, Inc., Austin, Texas; major contributions to the research were made by subcontractor Arizona State University, Tempe, Arizona. The objective of this research was to develop a HMA PRS based on spreadsheet solutions of the Mechanistic-Empirical Pavement Design Guide (MEPDG) originally developed in NCHRP Project 9-19, “Superpave Support and Performance Models Management,” as specification criteria for HMA rutting and fatigue cracking performance tests. This HMA PRS is now available as the QRSS. The QRSS is a stand-alone program for Microsoft Windows (versions XP and 7) that employs a database of pre-solved solutions of the MEPDG. The program is capable of (1) calculating the predicted rutting, fatigue cracking, and low-temperature (thermal) cracking of an HMA pavement from the mix volumetric and binder and aggregate properties of the as-designed HMA (typically the job mix formula) and (2) comparing them with pre- dictions calculated from the contractor’s lot or sub-lot quality assurance data for the same properties. The volumetric and materials properties are entered in the Witczak Predictive Equation to estimate values of the dynamic modulus (E*) that, in turn, are used to predict the development of rutting and fatigue cracking and the pavement service life based on the development of these distresses over time. For prediction of low-temperature cracking, the same volumetric and materials properties are used to estimate HMA creep and strength behavior. Finally, pay factor adjustment factors and payments (penalty/bonus) are derived from the predicted service life differences for each as-built lot or sub-lot. The QRSS gives project-specific performance predictions; the program accounts for climate, traffic, pavement structure, and the desired or expected pavement life in terms of distress limits assigned by the owner agency. Further, the distress predictions are stochastic; they are calculated through a Monte Carlo procedure that uses standard deviations of the input properties to account for construction and testing variabilities when assigning risk between the owner agency and the contractor and computing pay adjustment factors and payments. F O R E W O R D By Edward Harrigan Staff Officer Transportation Research Board

The report fully documents the research leading to the development of the QRSS proposed for review and possible adoption by AASHTO. In addition, five appendixes and the QRSS program are available for download from the NCHRP Project 9-22 web page at http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=958: APPENDIX A: Raw Data for Permanent Deformation Model Analysis APPENDIX B: Raw Data for Fatigue Cracking Model Analysis APPENDIX C: Summary of Results for Level 3 Creep Compliance Predictive Equations APPENDIX D: Hardening Ratio Database APPENDIX E: QRSS User’s Manual

C O N T E N T S 1 Chapter 1 Research Overview 1 1.1 Introduction 1 1.1.1 Background 1 1.1.2 Performance-Related Specification 2 1.1.3 Project History and Objectives 3 1.1.4 Organization of this Report 4 1.2 Scope of Study 4 1.2.1 MEPDG Based HMA Distress Prediction 4 1.2.2 Volumetrics-Based Performance Prediction in the QRSS 5 1.3 QRSS Overview 5 1.3.1 Development of a Probabilistic Methodology for Performance Pay Factors 5 1.3.2 Dynamic Modulus 6 1.3.3 Effective Temperature 6 1.3.4 MEPDG Closed Form Solutions 7 1.3.5 Probabilistic Solution 9 1.3.6 Service Life Prediction 9 1.3.7 Comparison of Mix Design and As-Built Mix Predicted Life Difference (PLD) 10 1.3.8 Determination of Pay Adjustment Factors 10 1.3.9 IRI in Pay Adjustment 11 1.3.10 Final Cost 14 Chapter 2 Development of the QRSS Performance Models 14 2.1 Introduction 14 2.2 General Variables 14 2.2.1 Effective Temperature 21 2.2.2 Determination of Dynamic Modulus (E*) 25 2.2.3 Determination of Creep Compliance 26 2.2.4 Frequency-Depth Relationship 31 2.3 Performance Model Development for Permanent Deformation 31 2.3.1 Introduction 31 2.3.2 Selection of Variables Affecting Rutting 33 2.3.3 Sub-Layering Scheme 35 2.3.4 Development of MEPDG Database 42 2.4 Performance Model Development for Fatigue Cracking 42 2.4.1 Introduction 42 2.4.2 Fatigue Distress Variables 47 2.4.3 Database Analysis and Results

56 2.5 Performance Model Development for Thermal Cracking 56 2.5.1 Introduction 56 2.5.2 Sensitivity Study 57 2.5.3 Mechanistic-Based Fracture Model Process 58 2.5.4 Input 59 2.5.5 Analysis 60 2.5.6 Output 60 2.5.7 Results 63 Chapter 3 Development of the Quality Related Specification and Software 63 3.1 Introduction 63 3.2 Determination of Deterministic Solution 66 3.2.1 Mix Design 69 3.2.2 E* Testing Temperature and Frequency 69 3.2.3 Dynamic Modulus-Distress Relationship for Rutting 69 3.2.4 Dynamic Modulus-Distress Relationship for FC 71 3.3 Determination of a Probabilistic Solution 71 3.3.1 Analysis of Variance for Significance of Regression 73 3.3.2 Monte Carlo Simulation 73 3.3.3 Rosenblueth Method 77 3.3.4 Historical Variance of Variables 77 3.3.5 Use of Beta Distribution 80 3.4 Application of Stochastic Methods in Performance Prediction 80 3.4.1 Application of Stochastic Methods to Dynamic Modulus 84 3.4.2 E* Variability Calculation 85 3.4.3 Application of Stochastic Methods on Rutting and FC 85 3.4.4 Application of Stochastic Methods to Thermal Cracking 87 3.5 Determination of Service Life and the Predicted Life Difference (PLD) 87 3.5.1 Conversion of Distress to Service Life for Rutting Distress 89 3.5.2 Conversion of Distress to Service Life for FC Distress 91 3.5.3 Conversion of Distress to Service Life for Thermal Cracking Distress 91 3.5.4 Comparison Between the As-Designed (JMF) Mix and the As-Built Mix Data 93 3.6 Pay Adjustment Factor and Payment (Penalty/Bonus) Computation 93 3.6.1 Three Distresses 95 3.6.2 Inclusion of IRI 99 Chapter 4 QRSS General Procedure 99 4.1 Introduction 99 4.2 Detailed Procedure 99 4.2.1 Mode Selection and General Information 99 4.2.2 User Input 105 4.2.3 Mix Design 106 4.2.4 Pay Adjustment Analysis (Stochastic Analysis of the As-Designed Mix) 115 4.2.5 Pay Performance Analysis (Stochastic Analysis for As-Built Mix) 123 4.2.6 Run Solution

130 Chapter 5 Summary, Conclusions, and Future Research 130 5.1 Summary 130 5.2 Conclusions 131 5.3 Proposed Future Research 132 References 134 Appendices A, B, C, D 135 Appendix E Quality Related Specification Software (QRSS) User’s Manual 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.