Volume 30, Issue 5 (September 2002)
Effect of Anisotropy on Compressive and Tensile Properties of Asphalt Mixtures
The research effort in this paper was part of the Superpave Support and Performance Models Management Project (Advanced Material Characterization) and was funded by the National Cooperative Highway Research Program Project 9–19. Anisotropy of hot mix asphalt materials greatly depends on specimen preparation, testing conditions, and test parameters under consideration. The objective of this study was to evaluate the anisotropy of selected test properties for specimens specially prepared with the Superpave gyratory compactor and cored in the vertical, horizontal, and diagnonal directions. The number of gyrations during compaction was adjusted on a trial-and-error basis to produce cores having air void contents of 4.0 ± 0.5% regardless of the direction of coring. Confined compression and tension tests were performed on the cored test specimens. The analysis included parameters such as the compressive / tensile strength, modulus of elasticity, and strain at failure. All test results were analyzed statistically. The majority of the test results (compression and tension) showed no significant effect of test specimen orientation on the test parameters at the 5% level of significance and for the test conditions used in the study. These results indicated that anisotropic effects might be ignored for the asphalt mixture used in this study using the special preparation method in the Superpave gyratory compactor.