Structure stability and shear failure behaviors of asphalt mixtures from the perspective of aggregate particle migration

Abstract

Shear deformation of asphalt mixtures is the macroscale accumulation of aggregate migration, addressing excessive aggregate slip and rotational migrations can reduce shear failure. In this research, the slip failure and torsional failure tests were introduced to achieve targeted investigations using developed instruments. Deformation resistance of the asphalt mixture was analyzed from the granular properties. The results indicate that shear energy is dissipated by structural self-organization induced by aggregate migration. Coarse gradation and complex aggregate morphology enhance the structure stability. The shear failure threshold resulting from aggregate slip exceeds that of rotation over fourfold. The packing coefficient (PC) and the critical moment of inertia (IC) were proposed to evaluate the slip and rotation resistances of asphalt mixtures, the indicators show good parabolic and linear relationships with the peak forces of slip and rotation as gradation changes, which can be illustrated by the interfacial friction and the spatial hindrance provided by the aggregate morphologies of texture and form. Finally, the findings were validated by the discrete element method.