Evaluating the interfacial properties between crumb rubber modified asphalt and aggregates using molecular dynamics simulation methods

Abstract

In the present study, the molecular dynamics (MD) simulation methods were used to investigate the interfacial properties of crumb rubber modified asphalt (CRMA)-aggregates considering the effects of crumb rubber (CR) degradation behavior and moisture. The interface models with different CR degradation degrees were then constructed. The interfacial adhesion properties between CRMA and aggregates were discussed by the interaction energy and work of adhesion; the agglomeration characteristics of CRMA on aggregates surface were evaluated by the radial distribution function (RDF); the diffusion behaviors of CRMA on aggregates surfaces were investigated using the mean square displacements (MSD); the asphalt adhesion strength test was performed to further verify the reliability of the simulation results. The results showed that the incorporation of CR into asphalt could significantly improve the adhesion and moisture damage resistance of the asphalt mixtures, while the CR degradation would slightly decrease these properties. The results of asphalt adhesion strength test exhibited similar trends with those of the work of adhesion, indicating that the simulation possessed a certain rationality. The RDF curves showed that the intrusion of water enlarged the distance between the polar components and aggregates, whereas the CR molecules displayed satisfactory agglomeration properties. Furthermore, the addition of CR weakened the mobility of asphalt on aggregates surface. This was mainly attributed to the poor mobility of the CR and its limitation on the mobility of the constituent components of asphalt. However, these problems would be alleviated as the CR degradation.