Molecular Simulation of Minerals-Asphalt Interfacial Interaction

The interfacial interaction between asphalt binder and mineral aggregate makes different components have different diffusion behavior. It influences the performance of interface and consequently that of the mix. In this research, the models of four asphalt components (asphaltene, resin, aromatics and saturate) and five minerals were constructed individually, and then the Al2O3-asphalt interface model was constructed by adding the asphalt layer and mineral layer together. The interfacial behavior at molecular scale was simulated by setting boundary conditions, optimizing the structure and canonical ensemble. The mean square displacement (MSD) and diffusion coefficient of particles were selected as indicators to study the diffusion of asphalt components on the surface of Al2O3. The results show that when the temperature was 65 °C, asphalt binder showed more viscosity, the diffusion speed of asphalt components ranked according to their molecular mass, which was saturate > aromatics > resin > asphaltene. At 25 °C and 165 °C, the resin had the fastest diffusion speed, which was nearly twice of asphaltene. The interaction between asphalt components and Al2O3 mineral surface can make the diffusion of asphalt components independent on temperature.