Investigation on the micromechanical response of asphalt mixture during permanent deformation based on 3D virtual wheel tracking test

Abstract

Based on the discrete element method (DEM), this paper conducted 3D virtual wheel tracking tests to predict the rutting of two types of asphalt mixture, and analyzed the micromechanical responses within asphalt mixtures during the process of rutting development. For achieving both accuracy and efficiency of the simulation, a newly-developed approach was proposed to build asphalt mixture model by using a MATLAB-based polyhedron generation algorithm and PFC5.0 codes. Linear contact model and Burger’s contact model were used to characterize the mechanical properties of coarse aggregates and asphalt mastic respectively. Virtual wheel tracking tests were built by a simplified equivalent loading assumption and scaled specimen, and then verified by laboratory tests. During the virtual test, the micromechanical response characteristics including the translation and rotation movement of aggregates, and three types of micro contacts within asphalt mixtures were statistically analyzed. Results showed virtual test can effectively predict the rutting of asphalt mixture. Moreover, the micromechanical response analysis revealed the load transmission path within asphalt mixture, and well explained the mechanism of rutting deformation from the perspective of micro discrete mechanics.