Dilation Behavior of Hot Mix Asphalt Under Triaxial Loading

ABSTRACT Permanent deformation generation in asphalt pavements has been explained to occur as a result of the initial traffic densification with the subsequent plastic flow. Recent studies indicate that asphalt concrete exhibits dilation under traffic loading; the displaced volume of asphalt mixture, including the downward depression in the wheel paths and the upheaval beside the wheel paths, is strongly correlated to the magnitude of rutting. In this study, triaxial strength testing was performed for both dense-graded mixtures and stone mastics asphalt mixtures. The dilation phenomenon was characterized by using the Corelok apparatus to measure the volume changes of the tested specimens at selected axial strains. The test results were analyzed using Mohr-Coulomb failure theory and Critical State Soil Mechanics theory, which studies the coupling effects of the density, volume change, and shear strength of soils.