Influence of Paraffin on the Microproperties of Asphalt Binder Using MD Simulation

Previous research has proved that paraffin has a negative effect on the mechanical properties of asphalt binder; however, until now there are very few studies on the fundamental mechanisms on a microscale. To study the effect of paraffin on the microproperties of asphalt binder, three molecular asphalt binder models with different paraffin contents and two molecular models of SBS-modified asphalt binders are created in this paper. The glass transition temperature is then simulated by means of a molecular dynamics (MD) simulation, indicating a significant reduction of low-temperature stability due to paraffin. Simulations of density, Young's moduli, Poisson's ratio, bulk moduli, and shear moduli are also conducted. The results show that paraffin can influence the mechanical properties substantially, and reduces the high-temperature stability of asphalt binders. Simulation results on the self-healing behavior of asphalt binder with varying paraffin contents demonstrate that paraffin significantly slows the self-healing behavior rate. Based on the molecular simulation results, it is suggested that the paraffin content in asphalt binder should be maintained at a controlled minimum amount. (C) 2018 American Society of Civil Engineers.