Simple Performance Tester for Superpave Mix Design: First-Article Development and Evaluation (2003)

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T R A N S P O R T A T I O N R E S E A R C H B O A R D WASHINGTON, D.C. 2003 www.TRB.org NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM NCHRP REPORT 513 Research Sponsored by the American Association of State Highway and Transportation Officials in Cooperation with the Federal Highway Administration SUBJECT AREAS Materials and Construction Simple Performance Tester for Superpave Mix Design: First-Article Development and Evaluation R.F. BONAQUIST D.W. CHRISTENSEN Advanced Asphalt Technologies, LLC Sterling, VA AND WILLIAM STUMP, III Calibration Services, Inc. Emlenton, PA

NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed research provides the most effective approach to the solution of many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation develops increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of cooperative research. In recognition of these needs, the highway administrators of the American Association of State Highway and Transportation Officials initiated in 1962 an objective national highway research program employing modern scientific techniques. 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The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished schol- ars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. On the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and techni- cal matters. Dr. Bruce M. Alberts is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Acad- emy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achieve- ments of engineers. Dr. William A. Wulf is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, on its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Acad- emy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both the Academies and the Institute of Medicine. Dr. Bruce M. Alberts and Dr. William A. Wulf are chair and vice chair, respectively, of the National Research Council. The Transportation Research Board is a division of the National Research Council, which serves the National Academy of Sciences and the National Academy of Engineering. The Board’s mission is to promote innovation and progress in transportation through research. In an objective and interdisciplinary setting, the Board facilitates the sharing of information on transportation practice and policy by researchers and practitioners; stimulates research and offers research management services that promote technical excellence; provides expert advice on transportation policy and programs; and disseminates research results broadly and encourages their implementation. The Board’s varied activities annually engage more than 4,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. www.TRB.org www.national-academies.org

COOPERATIVE RESEARCH PROGRAMS STAFF FOR NCHRP REPORT 513 ROBERT J. REILLY, Director, Cooperative Research Programs CRAWFORD F. JENCKS, NCHRP Manager EDWARD T. HARRIGAN, Senior Program Officer EILEEN P. DELANEY, Managing Editor HILARY M. FREER, Associate Editor II NCHRP PROJECT D09-29 PANEL Field of Materials and Construction—Area of Bituminous Materials LARRY L. MICHAEL, Maryland State Highway Administration (Chair) RONALD COMINSKY, Pennsylvania Asphalt Pavement Association, Harrisburg, PA GARY A. FREDERICK, New York State DOT CINDY LAFLEUR, Callanan Industries, Inc., Albany, NY DEAN A. MAURER, Pennsylvania DOT MURARI M. PRADHAN, Utah DOT JOHN “JACK” WEIGEL, JR., Payne & Dolan, Inc., Waukesha, WI THOMAS HARMAN, FHWA Liaison Representative JOHN D’ANGELO, Other Liaison Representative, FHWA LESLIE ANN MYERS, Other Liaison Representative, FHWA FREDERICK HEJL, TRB Liaison Representative AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Proj- ect 9-29 by Advanced Asphalt Technologies, LLC, and Calibration Services Incorporated. The work performed by Calibration Services Incorporated was under a subcontract to Advanced Asphalt Tech- nologies, LLC. The first-article simple performance test devices evaluated in this report were manufactured by Interlaken Technol- ogy Corporation and Shedworks Incorporated. The Federal High- way Administration assisted with the evaluation of the first-article devices. Ramon Bonaquist, Chief Operating Officer for Advanced Asphalt Technologies, LLC, served as Principal Investigator for the project. William Stump, III, President of Calibration Services Incor- porated was Co-Principal Investigator. Donald W. Christensen, Senior Engineer for Advanced Asphalt Technologies, LLC, and Dr. Charles Antle, consulting statistician, performed the statistical analyses that compose a significant portion of the evaluation included in this report. The report was written by Dr. Bonaquist, Mr. Stump, and Dr. Christensen. Work on this project was performed under the general supervi- sion of Ramon Bonaquist. Mr. Kevin Knechtel, Laboratory Man- ager for Advanced Asphalt Technologies, LLC, and Mr. Donald Jack, Chief Engineering Technician for Advanced Asphalt Tech- nologies, LLC, supervised the laboratory work performed during the project. Work in the Federal Highway Administration Mobile Asphalt Laboratory was performed by Dr. Leslie Myers, Mr. Charles Paugh, and Dr. Roustam Djoumanov.

This report presents the findings of a research project to develop a practical, eco- nomical simple performance tester for use in routine Superpave mix design and possi- bly in the characterization of hot mix asphalt (HMA) materials for pavement structural design. In the phase of the work reported here, first-article simple performance testers (SPTs) procured from two different manufacturers were evaluated, and both units were found to meet the requirements of the performance-based purchase specification. Based on these results, the Federal Highway Administration (FHWA) is coordinating a pooled-fund purchase of production units for evaluation by the state highway agencies. Four of these units will be immediately purchased in the next phase of this project for use by state highway agencies and FHWA to test the ruggedness of candidate simple performance tests. Thus, the report will be of particular interest to materials engineers in state highway agencies, as well as to materials suppliers and paving contractor per- sonnel responsible for design and production of hot mix asphalt and the specification and purchase of laboratory test equipment. The Superpave volumetric mix design procedure developed in the Asphalt Research Program (1987–1993) of the Strategic Highway Research Program (SHRP) does not include a simple, mechanical “proof” test analogous to the Marshall stability and flow tests or the Hveem stabilometer method. Instead, the original Superpave method relied on strict conformance to the material specifications and volumetric mix criteria to ensure satisfactory performance of mix designs intended for low-traffic-volume situations (defined as no more than 106 equivalent single axle loads [ESALs] applied over the ser- vice life of the pavement). For higher trafficked projects, the original SHRP Superpave procedures1 required a check for tertiary creep behavior with the repeated shear at con- stant stress ratio test (AASHTO TP7) and a rigorous evaluation of the mix design’s potential for permanent deformation, fatigue cracking, and low-temperature cracking using several other complex test methods in AASHTO TP7 and TP9. User experience with the Superpave mix design and analysis method, combined with the long-standing problems associated with the original SHRP Superpave perfor- mance models supporting what was then termed “level 2 and 3” analyses, demonstrated the need for simple performance tests (SPTs) to quickly and easily proof-test candidate mix designs. In 1996, work sponsored by FHWA (Contract DTFH61-95-C-00100) began at the University of Maryland at College Park (UMCP) to identify and validate SPTs for permanent deformation, fatigue cracking, and low-temperature cracking. In 1999, this effort was transferred to Task C of NCHRP Project 9-19, “Superpave Sup- port and Performance Models Management,” with the major portion of the task con- ducted by a research team headed by UMCP subcontractor Arizona State University (ASU). In NCHRP Report 465, the UMCP-ASU team recommended three candidate FOREWORD By Edward T. Harrigan Staff Officer Transportation Research Board 1 The Superpave Mix Design Manual for New Construction and Overlays, Report SHRP-A-407, Strategic Highway Research Program, National Research Council, Washington DC (1994).

test-parameter combinations as SPTs for permanent deformation: (1) the dynamic mod- ulus, E*, determined from the triaxial dynamic modulus test; (2) the flow time, FT, determined from the triaxial static creep test; and (3) the flow number, FN, determined from the triaxial repeated load test. Under NCHRP Project 9-29, “Simple Performance Tester for Superpave Mix Design,” Advanced Asphalt Technologies, LLC, was assigned the task of designing, procuring, and evaluating first-article SPTs for their potential use in Superpave mix design and in HMA materials characterization for pavement structural design. The first- article SPTs would be capable of conducting all three simple performance tests above; the units would further be evaluated for their capability to perform the dynamic mod- ulus master curve determination required for HMA materials characterization in the pavement design guide developed in NCHRP Project 1-37A, “Development of the 2002 Guide for the Design of New and Rehabilitated Pavement Structures: Phase II.” In the first stage of this work, the research team reviewed the draft test protocols prepared by the Project 9-19 research team. This review included a 1-day workshop attended by the project panel, key members of the research team, and invited materials testing experts to discuss the requirements for the simple performance test devices. The team then developed draft equipment specifications and cost estimates for each of the three candidate simple performance tests; these were then combined to specify a sin- gle device capable of performing all three tests. The team conducted a workshop with the project panel and potential manufactur- ers to review the draft specifications and cost estimates; comments from the workshop participants were incorporated into the first-article purchase specification. Finally, the team prepared a work plan for evaluation of the first-article equipment. In the second stage of the work, proposals for procurement of first-article SPTs were solicited from several equipment manufacturers. Four proposals were received; purchase orders for first-article SPTs were awarded to Interlaken Technology Corpo- ration and Shedworks, Inc. Upon delivery, these units were extensively evaluated through a joint effort of Advanced Asphalt Technologies, LLC, and the Federal High- way Administration to (1) ensure they were in compliance with the specifications and properly calibrated, (2) evaluate HMA mechanical properties measured with the two devices, and (3) assess their overall functionality. Both first-article SPTs were found to meet all requirements of the performance-based purchase specification and to be reasonably user-friendly. The overall variability of the simple performance test based on E* conducted with either first-article unit was found acceptable for purposes of HMA mix design or quality control testing; however, the vari- ability of the test based on the FN parameter was judged too high for either purpose. As presently configured, the SPT cannot reach the lowest test temperature speci- fied for determination of the dynamic modulus master curve according to the protocol developed in NCHRP Project 1-37A, “Development of the 2002 Guide for the Design of New and Rehabilitated Pavement Structures: Phase II.” In the next phase of the pro- ject, alternative methods for estimating limiting low temperature modulus will be eval- uated to determine the minimum required testing temperature range for equipment to measure the dynamic modulus master curves. Based on these results, a production SPT fully capable of accurately measuring the master curve will be procured. This report describes the development of the first-article purchase specification, procurement and evaluation of the two SPTs, and the ensuing revision of the purchase specification for future procurement of production SPT units. In addition, it contains four supporting appendixes: • Appendix A: First-Article Equipment Specifications; • Appendix B: Materials and Laboratory Methods; • Appendix C: Evaluation Test Data; and • Appendix D: Revised Equipment Specification.

CONTENTS 1 SUMMARY 3 CHAPTER 1 Introduction and Research Approach 1.1 Problem and Purpose, 3 1.2 Scope and Research Approach, 3 5 CHAPTER 2 Findings 2.1 Key Elements of the First-Article Specification, 5 2.2 First-Article Equipment, 14 2.3 First-Article Equipment Evaluation, 19 44 CHAPTER 3 Interpretation, Appraisal, and Applications 3.1 First-Article Specification Modifications, 44 3.2 Acceptability of First-Article Devices, 47 3.3 Draft Test Methods for the Simple Performance Test System, 48 52 CHAPTER 4 Conclusions and Recommendations 4.1 Conclusions, 52 4.2 Recommendations, 52 54 REFERENCES A-1 APPENDIX A First-Article Equipment Specifications B-1 APPENDIX B Materials and Laboratory Methods C-1 APPENDIX C Evaluation Test Data D-1 APPENDIX D Final Equipment Specification