Molecular Dynamics Study of the Interface Behavior of Asphalt–Aggregate Systems Considering the Salt Solution Environment

To investigate the adhesion characteristics of different asphalt-aggregate (A-A) interfaces under salt solution erosion. Clean water and 8% saline solution were selected, and molecular dynamics (MD) simulation was performed to establish a model of rubber powder-modified asphalt (CR)/SBS modified asphalt (SBS)-water/salt solution-steel slag/basalt interface. Study on the mechanism of interaction between asphalt molecules and aggregate minerals through diffusion coefficient, RDF and interfacial adhesion energy density. Based on the surface energy theory, the adhesion work between different asphalt and aggregate was calculated to verify its rationality. The results show that the degradation effect of Cl− and Na+ in salt solution on the interfacial adhesion of A-A system is much stronger than that of water molecules. The denser molecular aggregation makes the A-A system have better adhesion characteristics. Regardless of water or salt solution, the adhesion of the A-A interface is CR-steel slag > SBS-steel slag > CR-basalt > SBS-basalt.