Discrete-Element Modeling of Mean Texture Depth and Wearing Behavior of Asphalt Mixture

The mean texture depth (MTD) of asphalt pavement surface is an important indicator of skid resistance of asphalt pavement. This paper aimed to analyze the wearing behavior of asphalt mixtures under repetitive tire loads using discrete element modeling (DEM). An algorithm was developed to generate the two-dimensional (2D) microstructure of an asphalt mixture model using DEM considering real shapes of aggregates. The evolution of the surface texture of asphalt mixtures under repeated tire loads was simulated due to aggregate wear and asphalt mortar deformation in DEM. The degradation curve of the MTD of an asphalt mixture with the number of loading cycles was obtained and verified using laboratory testing results. The degradation trend of the MTD was captured as a function of the loading cycle and three fitting parameters that can be obtained from simulation results. A decrease in the MTD of asphalt pavement was found to be significantly affected by the applied stress and tire rubber stiffness. A conversion method was further developed to predict the long-term value of the MTD after a large number of loading cycles. The study findings are useful for understanding the degradation of the surface texture of asphalt mixtures at the microscopic level.