Molecular Dynamics Simulation and Experimental Validation of Diffusion Performance and Compatibility in Rock Asphalt/Styrene–Butadiene Rubber Composite–Modified Asphalt

In order to reveal the influence mechanism of rock asphalt (RA) and styrene–butadiene rubber (SBR) on the thermophysical properties of asphalt at the molecular scale, this study employed the molecular dynamics simulation method. Molecular models of base asphalt, RA‐modified asphalt (RAMA), SBR‐modified asphalt (SBRMA), and RA/SBR‐modified asphalt (RSMA) were constructed. The simulation results were verified through storage stability and rotational viscosity tests. The research shows that as the temperature increases, the diffusion ability of asphalt enhances, and the storage stability improves, but the intermolecular bonding strength shows a decreasing trend. Under isothermal conditions, the incorporation of both RA and SBR can effectively inhibit the migration of asphalt molecules, and the inhibitory effect of RA is more significant. Compared with SBR, RA exhibits better compatibility with base asphalt, and its presence can improve the compatibility between SBR and base asphalt. Based on the analysis of the differences in molecular polarity, the binding energy of RAMA is significantly higher than that of SBRMA, and RSMA can further enhance the bonding strength under the synergistic effect of the two modifiers. The experimental data indicate that the variation laws of storage stability and viscosity–temperature characteristics are highly consistent with the simulation results, confirming the reliability of the molecular simulation method.