Laboratory Characterization and Empirical Prediction of Dynamic Modulus of Superpave Mixtures (05-2714)**
Louay N. Mohammad, Louisiana State University
Zhong Wu, Louisiana Transportation Research Center
Leslie Myers McCarthy, Villanova University
Zhang Zhongie, Louisiana State University
Christopher David Abadie, Louisiana Department of Transportation and Development

ABSTRACT The Dynamic Modulus |E*| test has been recommended by the National Cooperative Highway Research Program (NCHRP) Project 9-19 to be one of the Simple Performance Tests (SPTs) for performance prediction of asphalt concrete mixtures. This paper presents the results of a comprehensive collaboration study of dynamic modulus testing between two laboratories using two 25-mm Superpave mixtures. Multiple temperature and frequency sweeps were used in the testing. The sensitivity and repeatability of dynamic modulus test results were evaluated based on the test results measured from two laboratories. In addition, two currently most popular dynamic modulus prediction models: Hirsch and Witczak’s models, were employed in this study to predict the dynamic modulus of the two Superpave mixtures considered. The results of this study indicated that the dynamic modulus test generally can have a test variability in terms of the percent coefficient of variation as high as 20 percent among duplicate samples of a mixture. The dynamic modulus values of an asphalt mixture seemed to be sensitive to binder contents in the mixture. At high rutting temperature, both the rutting parameter, |E*|/sinö, and laboratory Hamburg rut tests can predict the rutting potentials of the two mixtures considered in this study consistently. In addition, the variability of dynamic modulus results between two laboratories can be higher than 20 percent. Finally, it was found that both the Witczak’s and the Hirsch models can predict the dynamic modulus values from mixtures properties within a reasonable reliability