Aggregate Tests for Hot-Mix Asphalt Mixtures Used in Pavements (2006)

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TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2006 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 557 Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration Subject Areas Pavement Design, Management, and Performance • Materials and Construction Aggregate Tests for Hot-Mix Asphalt Mixtures Used in Pavements Thomas D. White MISSISSIPPI STATE UNIVERSITY Mississippi State, MS John E. Haddock PURDUE UNIVERSITY West Lafayette, IN Erza Rismantojo PT SOILENS Bandung, Indonesia

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CRP STAFF FOR NCHRP REPORT 557 Robert J. Reilly, Director, Cooperative Research Programs Crawford F. Jencks, NCHRP Manager Amir N. Hanna, Senior Program Officer Eileen P. Delaney, Director of Publications Hilary Freer, Senior Editor Natalie Barnes, Editor NCHRP PROJECT 4-19(2) PANEL Field of Materials and Construction—Area of General Materials Richard L. Stewart, South Carolina DOT (retired) (Chair) Paul T. Foxworthy, ERES Consultants, Inc., Overland Park, KS Vernon J. Marks, Iowa DOT (retired) Richard C. Meininger, Columbia, MD Larry A. Scofield, Arizona DOT (retired) William Sheftick, Illinois DOT (retired) William H. Skerritt, New York State DOT Stephen Forster, FHWA Liaison Thomas Harman, FHWA Liaison G.P. Jayaprakash, 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 presents recommendations for performance-based procedures to test aggregates for use in pavements utilizing hot-mix asphalt (HMA) mixtures and provides guidance on using these procedures for evaluating and selecting aggregates for use in specific mixture appli- cations. This information will guide materials engineers in selecting the aggregates that should contribute to well performing pavements; this information can also be used in conjunction with performance-related specifications. The content of this report will be of immediate interest to materials engineers, researchers, and others concerned with the construction and performance of HMA pavements. The properties of coarse and fine aggregates used in HMA mixtures significantly affect the performance of the highway pavements in which they are used. Despite their obvious importance, little consideration is usually given to the testing of aggregates. Many currently used aggregate tests are empirical—they were developed without establishing a direct rela- tion to pavement performance. Furthermore, some of the most commonly used test meth- ods are not easy to perform and do not yield reproducible results; compliance with these tests does not consistently result in acceptable performance. Thus research was needed to recommend precise tests that measure key aggregate properties related to pavement perfor- mance. The tests are for use in evaluating and selecting aggregates or in conjunction with performance-related specifications. Research performed under NCHRP Project 4-19, reported in NCHRP Report 405: Aggre- gate Tests Related to Asphalt Concrete Performance in Pavements, evaluated aggregate tests through a study of literature and laboratory tests. The research then identified a set of nine aggregate tests that relate to the performance of HMA mixtures used in pavement construc- tion and thus can be used as predictors of pavement performance. However, the project did not assess the validity of these tests by in-service performance tests or accelerated pavement tests. Under NCHRP Project 4-19(2), “Validation of Performance-Related Tests of Aggre- gates for Use in Hot-Mix Asphalt Pavements,” Purdue University of West Lafayette, Indiana, (with Mississippi State University serving as a subcontractor) was assigned the objective of evaluating, by accelerated load tests and/or in-service pavement studies, the validity of the aggregate tests identified in NCHRP Project 4-19 as predictors of field performance of HMA mixtures and then recommending performance-based test methods. The research concen- trated on dense-graded virgin HMA used in the top layers of high-load, high-volume pave- ments. To accomplish this objective, the researchers performed the following tasks: 1. Review and synthesis of information relevant to the testing and evaluation of aggregates used in HMA pavements; F O R E W O R D By Amir N. Hanna Staff Officer Transportation Research Board

2. Characterization of a wide variety of aggregate types and selection of five coarse and six fine aggregates representing a range of properties for use in the research; 3. Conduct of accelerated fatigue and rutting tests of full-scale pavement sections con- structed with HMA mixtures containing aggregates of different types and properties to correlate performance with the aggregate properties measured in the laboratory using the test methods identified in NCHRP Report 405; data from rutting tests were also used to assess moisture susceptibility; 4. Analysis of test results to (a) evaluate the effect of specific aggregate properties on per- formance, (b) determine the sensitivity of these aggregate properties to traffic level, and (c) evaluate the validity of the previously identified tests; and 5. Recommendation of a set of tests for evaluating aggregates used in HMA pavements and proposed acceptance criteria for different levels of traffic. The recommended set of eight aggregate tests deals with particle shape, angularity, sur- face texture, durability, and soundness of the aggregates and with the characteristics of the fines in aggregates. These tests and the proposed acceptance criteria can be used to select aggregates for use in HMA mixtures or in conjunction with performance-related specifica- tions. These test methods will be particularly useful to highway agencies and are recom- mended for consideration and adoption by AASHTO as standard test methods. Appendixes A through F contained in the research agency’s final report are not published herein. These appendixes are accessible on the web as NCHRP Web-Only Document 82 at http://www4.trb.org/trb/onlinepubs.nsf. These appendixes are titled as follows: Appendix A: Petrographic Analysis Results; Appendix B: Laboratory HMA Mixture Design Results; Appendix C: Aggregate Tests; Appendix D: Test Section Construction and Control; Appendix E: Moisture Susceptibility; and Appendix F: Bibliography.

C O N T E N T S 1 Summary 3 Chapter 1 Introduction and Research Approach 3 Problem Statement and Research Objectives 3 Scope of Study 3 Research Approach 8 Chapter 2 Findings 8 State-of-the-Art Summary 10 Aggregate Test Results 15 Mixture Designs 17 Accelerated Pavement Test Results 24 Chapter 3 Interpretation, Appraisal, and Application 24 Coarse-Graded Mixtures 26 Fine-Graded Mixtures 30 Moisture Susceptibility Mixtures 33 Fatigue Mixtures 34 Chapter 4 Conclusions and Suggested Research 34 Coarse Aggregate Uncompacted Voids Content 34 Flat or Elongated Particles 35 Fine Aggregate Uncompacted Void Content 36 Methylene Blue Test 36 Particle Size Analysis 36 Micro-Deval and Magnesium Sulfate Soundness 36 Summary 36 Recommended Research 38 References