Mesoscopic creep mechanism of asphalt mixture based on discrete element method

Abstract

In order to investigate creep mechanism of asphalt mixtures from the mesoscopic level, a virtual dynamic creep test of asphalt mixture was conducted with two-dimensional discrete element method (DEM). Based on the probability theory and the Monte-Carlo method, a random generation algorithm was used to generate aggregate particles with irregular shapes. The virtual dynamic creep test, including the modeling of a virtual asphalt mixture specimen, the selection of contact models and mesoscopic parameters, and the realization of semi-sine wave intermittent dynamic loading, was simulated based on DEM. Then the simulation results were verified via the experimental dynamic creep test. It is demonstrated that the discrete element model effectively simulated the dynamic creep test, in which the relative error is less than 10% in general. During the simulation test, the contact force in the asphalt mixture was evenly distributed at the beginning of loading, but part of the contact bond was broken, and then redistributed and stress concentration appeared in the failure period. In addition, with the increase of temperature or contact pressure, the axial strain of asphalt mixture increased, and the resistance to permanent deformation decreased, which is consistent with law of the laboratory test. Moreover, the relation between the elastic modulus and axial strain in Burgers model indicates that the modulus of Burgers model is closely correlated with permanent deformation of asphalt mixture.