Evaluation of aspects of E^* test by using hot-mix asphalt specimens with varying void contents

A dynamic modulus master curve for asphalt concrete is a critical input for flexible pavement design in the Mechanistic-Empirical Pavement Design Guide developed in NCHRP Project 1-37A, which has drawn much attention among asphalt technologists. The objectives in this study were (a) to consider and compare different analysis techniques for construction of the master curve and (b) to measure and analyze the effect of permanent strain on samples that have been evaluated with one of the simple performance tests, dynamic modulus. It was found that differences existed in the calculated asymptote values and the shape of the master curve, depending upon which method was adopted. Recommendations are made for modifications to the testing protocol and for further work to determine the effect of permanent strain at higher test temperatures.