Virtual-specimen modeling of aggregate contact effects on asphalt concrete

Abstract

Aggregate contacts significantly affect the mechanical behavior of asphalt concrete. However, there still lacks an effective way to account for them in numerical modeling. Therefore, to address this concern, a new virtual-specimen-based modeling approach was developed in this study by simplifying aggregate particles in asphalt concrete as spheres and incorporating aggregate contacts through Contact Region (CR) elements. The complex moduli of both gap-graded and dense-graded mixtures were predicted using this approach and compared with those predicted using the conventional image-based modeling approach and laboratory-measured values. The virtual-specimen modeling revealed that the CR in the gap-graded mixture with a higher proportion of large aggregates can better transmit load among aggregates than in the dense-graded mixture. Both modeling approaches were found to provide good prediction accuracy, but the stress distributions in the virtual-specimen models were more uniform and continuous, leading to better computational convergence and the possibility of nonlinear analysis of asphalt concrete.