Evaluation of the Anisotropy of Asphalt Mixtures

Abstract

A proper understanding of the anisotropic behavior of asphalt mixtures is required for an accurate multiaxial characterization of asphalt mixtures under different loading conditions. Asphalt mixtures are subjected to various loading conditions while in service. This study evaluates the anisotropy of asphalt mixtures under application of hydrostatic pressure. The results demonstrated that the anisotropy is dependent on the mix design. Asphalt mixtures with coarse aggregate gradations were found to have a higher level of anisotropy compared with mixtures with finer aggregate gradations. In addition, the induced anisotropy increased with the increase of confining pressure and temperature. Finally, the porosity of the asphalt mixture had a relatively significant impact on both inherent and induced anisotropy. The induced anisotropy increased with the increase of porosity. Furthermore, the analysis of the inherent anisotropy using X-ray computed tomography and image analysis techniques confirmed that the degree of inherent anisotropy decreases with the increase of density.