Micromechanical Simulation of Hot Mix Asphalt

A model based on the discrete element method (DEM), ASBAL, was developed by modifying the TRUBAL program to simulate hot mix asphalt (HMA). To represent asphalt cement, several viscoelastic elements (i.e., Maxwell, Kelvin-Voigt, and Burger's elements) were considered. The research results from the Strategic Highway Research Program (SHRP) were used for the selection of proper element. From these viscoelastic elements the Burger linear viscoelastic element is shown to be the most promising element for modeling asphalt binder behavior, based on mechanical responses and comparisons with physical experimental results. Therefore, Burger's elements were added in normal and tangential directions to each aggregate-asphalt-aggregate contact to simulate the asphalt binder in HMA assemblies. This new model is called ASBAL (TRUBAL for Asphalt). Several monotonic and cyclic tests were simulated to observe and fine-tune the model ASBAL. A carefully conducted physical experiment with X-ray tomographs was simulated and compared. The simulation based on the ASBAL model compared well with experimental results.