Effect of Radial Inhomogeneity on Shear Properties of Asphalt Mixtures

Abstract

Radial inhomogeneity is often observed in superpave gyratory compacted specimens because of the rotational movement of the gyratory and the boundary condition imposed by the gyratory mold. The effect of the inhomogeneity on mechanical properties of asphalt mixtures is not known. To study this effect, laboratory specimens of asphalt mixtures with known levels of aggregate inhomogeneity were fabricated. Nondestructive X-ray computed tomography was used to scan cross-sectional images of the specimens. A statistical index was developed to evaluate the scanned images for radial inhomogeneity. The results clearly show that the index can distinguish between levels of inhomogeneity. By means of frequency sweep at constant height (FSCH) test, the shear stiffness and the fatigue susceptibility at test temperature of