Discrete element modeling for the superpave gyratory compactor test of asphalt mixture: Analysis of contact model parameters

This study established the ball-based and the clump-based Discrete Element Method (DEM) simulation of the Superpave Gyratory Compactor (SGC) tests. The Burger’s model and the contact bond model were employed to simulate the compaction behavior of asphalt mixture. The influence of the contact model parameters, such as the friction coefficient (f sub s) and viscosity parameters (E sub k, E sub m, η sub k, and η sub m) and bond strength (T sub s), upon the compatibility of asphalt mixture were simulated through the established ball-based SGC DEM models. Based on the sensitivity analysis of the contact parameters and the lab test results, a micro-parameters calibration method was proposed. This method produced a simulation that displayed good congruity. The influence of aggregates shapes was also investigated through lab tests and the clump-based DEM simulation of three groups of samples with rounded, fractured, and original coarse aggregates shapes. The friction coefficient was found to have significant influence on the initial and final void ratio; bond strength was critical to the changes in trend of void ratio. In contrast, viscosity parameters in the Burger’s model were found to have limited influence on the compatibility. With respect to aggregates shape, the clump-based SGC DEM models, except during the unstable early stage of compaction, were found to have good congruity with lab tests. Furthermore, fractured and rounded coarse aggregates produced a negative trend with respect to void ratio when compared with the original specimens in both lab tests and DEM simulation