Performance Testing for Superpave and Structural Validation PUBLICATION NO. FHWA-HRT-11-045 NOVEMBER 2012 Research, Development, and Technology Turner-Fairbank Highway Research Center 6300 Georgetown Pike McLean, VA 22101-2296 FOREWORD This final report provides the comprehensive findings from two Transportation Pooled Fund (TPF) research projects, TPF-5(019): Full-Scale Accelerated Performance Testing for Superpave and Structural Validation and SPR-2(174): Accelerated Pavement Testing of Crumb Rubber Modified Asphalt Pavements. The research identified candidate purchase specification tests for asphalt binder that better discriminate expected fatigue cracking and rutting performance than current SUperior PERforming Asphalt PAVEment (Superpave®) tests. Full-scale accelerated pavement testing and laboratory characterization tests on mixtures and binders provided the basis for the recommendations. This report documents a historical review of the development of asphalt binder performance specifications, experimental design, test pavement construction and performance, statistical methodology to rank and identify the strongest candidates, and all pertinent laboratory characterization of binders and mixtures that supplemented the recommendations. The research also provided a detailed case study of pavement evaluation using falling weight deflectometer and objective means to evaluate two emerging technologies; the asphalt mixture performance tester and the Mechanistic-Empirical Pavement Design Guide.(1) This document will be of interest to highway personnel involved with Superpave®, materials selection, performance specifications, and pavement design and evaluation. Jorge E. Pagán-Ortiz Director, Office of Infrastructure Research and Development Notice This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document. This report does not constitute a standard, specification, or regulation. The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers’ names appear in this report only because they are considered essential to the objective of the document. Quality Assurance Statement The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement. TECHNICAL REPORT DOCUMENTATION PAGE 1. Report No. 2. Government Accession No. 3 Recipient’s Catalog No. FHWA-HRT-11-045 4. Title 5. Report Date Performance Testing for Superpave and Structural Validation November 2012 6. Performing Organization 7. Author(s) 8. Performing Organization Report No. Nelson Gibson, Xicheng Qi, Aroon Shenoy, Ghazi Al-Khateeb, M. Emin Kutay, Adrian Andriescu, Kevin Stuart, Jack Youtcheff, and Thomas Harman 9. Performing Organization Name and Address: 10. Work Unit No. Office of Infrastructure Research and Development Federal Highway Administration 11. Contract or Grant No. 6300 Georgetown Pike McLean, VA 22101-2296 12. Sponsoring Agency Name and Address 13. Type of Report and Period TPF-5(019): Connecticut, Florida, Kansas, Maryland, Mississippi, Final Report Montana, New Jersey, New York, Nebraska, Nevada, Pennsylvania, Texas January 2002–January 2008 SPR-2(174): Florida, Illinois, Iowa, Kansas, Michigan, Minnesota, 14. Sponsoring Agency Code Montana, North Carolina, New York, Oregon, Texas 15. Supplementary Notes A project database is available upon request from FHWA Office of Infrastructure Research & Development. The Task Manager was Nelson Gibson, HRDI-10. 16. Abstract The primary objective of this full-scale accelerated pavement testing was to evaluate the performance of unmodified and polymer modified asphalt binders and to recommend improved specification tests over existing SUperior PERforming Asphalt PAVEment (Superpave®) binder performance grading methodologies. Candidate replacement tests were evaluated via their ability to discern fatigue cracking resistance and rutting. Two fatigue cracking specification tests were identified as more capable in capturing performance than others: binder yield energy and critical tip opening displacement. Two rutting specification tests that quantify irrecoverable deformations exhibited the best strength to capture rutting: multiple stress creep and recovery and oscillatory-based nonrecoverable stiffness. Based on the full-scale performance and laboratory tests, crumb rubber (recycled tires) modified asphalt (Arizona wet process) was shown to significantly slow or stop the growth of fatigue cracks in a composite asphalt pavement structure. A hybrid technique to modify asphalt with a combination of crumb rubber and conventional polymers (terminally blended) exhibited good fatigue cracking resistance relative to the control binder. Also, a simple addition of polyester fibers to asphalt mix was shown to have high resistance to fatigue cracking without the use of polymer modification. The research study also quantified the capabilities of the National Cooperative Highway Research Program’s mechanistic-empirical pavement design and analysis methodologies to predict rutting and fatigue cracking of modified asphalts that were not captured in the calibration data from the Long-Term Pavement Performance program. Falling weight deflectometer, multidepth deflectometer, and strain gauge instrumentation were used to measure pavement response. The results illustrated that the nationally calibrated mechanistic-empirical performance models could differentiate between structural asphalt thickness but had difficulty differentiating modified from unmodified asphalt binder performance. Nonetheless, the mechanistic-empirical performance ranking and predictions were enhanced and improved using mixture-specific performance tests currently being implemented using the asphalt mixture performance tester. 17. Key Words 18. Distribution Statement APT, ALF, Fatigue cracking, Rutting, Superpave, Asphalt No restrictions. This document is available to the public binder specification, FWD, Mechanistic-empirical through the National Technical Information Service, pavement design, Asphalt mixture performance tests Springfield, VA 22161 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 271 Form DOT F 1700.7 (8-72) Reproduction of completed page authorized SI* (MODERN METRIC) CONVERSION FACTORS APPROXIMATE CONVERSIONS TO SI UNITS Symbol When You Know Multiply By To Find Symbol LENGTH in inches 25.4 millimeters mm ft feet 0.305 meters m yd yards 0.914 meters m mi miles 1.61 kilometers km AREA in2 square inches 645.2 square millimeters mm2 ft2 square feet 0.093 square meters m2 yd2 square yard 0.836 square meters m2 ac acres 0.405 hectares ha mi2 square miles 2.59 square kilometers km2 VOLUME fl oz fluid ounces 29.57 milliliters mL gal gallons 3.785 liters L ft3 cubic feet 0.028 cubic meters m3 yd3 cubic yards 0.765 cubic meters m3 NOTE: volumes greater than 1000 L shall be shown in m3 MASS oz ounces 28.35 grams g lb pounds 0.454 kilograms kg T short tons (2000 lb) 0.907 megagrams (or "metric ton") Mg (or "t") TEMPERATURE (exact degrees) oF Fahrenheit 5 (F-32)/9 Celsius oC or (F-32)/1.8 ILLUMINATION fc foot-candles 10.76 lux lx fl foot-Lamberts 3.426 candela/m2 cd/m2 FORCE and PRESSURE or STRESS lbf poundforce 4.45 newtons N lbf/in2 poundforce per square inch 6.89 kilopascals kPa APPROXIMATE CONVERSIONS FROM SI UNITS Symbol When You Know Multiply By To Find Symbol LENGTH mm millimeters 0.039 inches in m meters 3.28 feet ft m meters 1.09 yards yd km kilometers 0.621 miles mi AREA mm2 square millimeters 0.0016 square inches in2 m2 square meters 10.764 square feet ft2 m2 square meters 1.195 square yards yd2 ha hectares 2.47 acres ac km2 square kilometers 0.386 square miles mi2 VOLUME mL milliliters 0.034 fluid ounces fl oz L liters 0.264 gallons gal m3 cubic meters 35.314 cubic feet ft3 m3 cubic meters 1.307 cubic yards yd3 MASS g grams 0.035 ounces oz kg kilograms 2.202 pounds lb Mg (or "t") megagrams (or "metric ton") 1.103 short tons (2000 lb) T TEMPERATURE (exact degrees) oC Celsius 1.8C+32 Fahrenheit oF ILLUMINATION lx lux 0.0929 foot-candles fc cd/m2 candela/m2 0.2919 foot-Lamberts fl FORCE and PRESSURE or STRESS N newtons 0.225 poundforce lbf kPa kilopascals 0.145 poundforce per square inch lbf/in2 *SI is the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380. (Revised March 2003) ii TABLE OF CONTENTS CHAPTER 1. INTRODUCTION .................................................................................................1 BACKGROUND ......................................................................................................................1 Current Asphalt Binder Specifications ................................................................................1 Post-SHRP Full-Scale Validation of Binder Specification ................................................12 Identified Shortcomings with Current Asphalt Binder Specifications ..............................16 PROBLEM STATEMENT ...................................................................................................18