Using molecular dynamics simulation to study concentration distribution of asphalt binder on aggregate surface

The interfacial interaction between asphalt binder and mineral aggregate makes different components have different concentration distributions. It influences the performance of the interface and consequently that of the mix. An asphalt binder-mineral aggregate interface model was built by molecular dynamics (MD) simulation. Four asphalt components and five mineral components were selected to analyze the concentration distribution at the interface. Results show that the concentration peak distribution of asphalt components was dependent on directions. The concentration peak perpendicular to the surface of minerals was higher than that parallel to the surface of minerals. Increasing temperature accelerated the movement of four asphalt components, resulting in reduction and widening of concentration peaks. Increasing temperature made four asphalt components disperse more homogeneously. The resin and asphaltene had similar concentration distribution curve forms, but the peaks of resin lagged behind asphaltene. In contrast, the concentration distribution of aromatics and saturates was more random and homogeneous.