Mesomechanics simulation of micro-crack extension process for asphalt mixture

Marshall numerical specimens of asphalt mixture were made by using discrete element method, indirect tensile test was conducted, the influences of parallel-bond strength ratios, particle friction coefficients and loading velocities on micro-crack extension processes were studied, and the mesomechanics responses of particles in the specimens were analyzed.Simulated result indicates that the bonding characteristics of asphalt are more obvious when the parallel-bond strength ratio is larger, which makes the types of micro-cracks change from normal micro-cracks to tangential micro-cracks.When the ratio changes from 0.500 to 4.000, the contact force reduces by 78.05%, and the displacement reduces by 78.57%.The roughness of aggregate increases with the increase of friction coefficient.When the coefficient changes from 0.3 to 0.7, the contact force increases by 31.21%, and the displacement reduces by 21.45%, but there is little effect on the distribution of micro-cracks that are mainly normal micro-cracks.When the loading velocity changes from 0.03 mm·s^-1 to 0.07 mm·s^-1, the contact force increases by 3.50%, and the types and numbers of micro-cracks and the amounts of displacements do not change basically.Loading conditions have less effect on micro-crack extension compared with asphalt and aggregate.