Wetting Behavior and Failure Mechanism of Asphalt–Aggregate Interface Based on Molecular Dynamics Simulations

Environmental factors, such as aging and water, can lead to the failure and damage of the asphalt–aggregate interface, accelerating the occurrence of asphalt pavement diseases. This study investigates the wetting behavior and failure mechanism of asphalt–aggregate interface using molecular dynamics (MD) simulations. The diffusion behavior of nano-water droplets on different mineral surfaces (quartz, calcite, and albite) is simulated to characterize the wettability of aggregates. The adhesion work and ratio of adhesion energy loss are calculated to explore the failure mechanism of interfaces under aging-water coupling effects. The investigation finds that nano-water droplets quickly wet mineral surfaces, impacting the adhesion of asphalt-mineral interface and leading to deterioration or even failure of the interface system. Debonding damage to the interface under the influence of water occurs spontaneously. The debonding work indicates that the interface resistance to the stripping of the three minerals follows the order of albite, calcite, and quartz from high to low. Compared with virgin asphalt (VA), the ratio of adhesion energy loss manifests that lightly oxidized asphalt (LOA)-water coupling enhances the interface resistance to water damage, whereas heavily oxidized asphalt (HOA)-water coupling accelerates interface failure and damage.