Simulating the Micromechanical Behavior of Porous Asphalt Mixture Using Discrete Element Method

Abstract

The motivation of this research is to simulate the micromechanical behavior of asphalt mixtures using the Discrete Element Method (DEM). A bonded-contact model, named as EVCM, was developed to describe the micromechanical behavior of asphalt mixture, based on linear elastic and Burger’s viscoelastic constitutive equations. The EVCM is a new user-defined model implemented in the EDEM software. The microscale parameters of asphalt mortar were characterized by fitting the Burger’s model to Dynamic Shear Rheometer (DSR) data. A simple model was developed to evaluate EVCM, and the produced analysis successfully indicated that the trends of computations fall within the range of values expected of typical asphalt mixture materials and the EVCM is sensitive to the loading rate. Further, a Superpave Gyratory Compaction (SGC) test was carried out to compact a porous asphalt mixture and the obtained specimen was scanned using X-ray Computed Tomography (X-ray CT) to capture the air void distributions. The DEM was utilized to simulate the overall process of the SGC laboratory test where a digital specimen was established. The simulation predictions have shown agreement with the lab results and proved the ability of the EVCM to simulate and predict the micromechanical behavior of a PA mixture across a range of temperatures. The model was employed to assess the air voids distribution showing a good agreement at the top, but an opposing trend at the bottom.