Interfacial interaction behavior of recycled asphalt pavement: Molecular dynamics simulation

Recycling waste asphalt mixture (WAM) to prepare recycled asphalt pavement (RAP) is an important measure to handle road construction waste. Asphalt-aggregate interface (AAI) and matrix-aged asphalt interface (MAI), as weak interfaces in RAP, interface interaction behavior directly affects the road performance of RAP. In this paper, molecular models of asphalt and aggregate were constructed. Molecular dynamics simulation was used to analyze and evaluate the interaction behavior of the AAI and the MAI in RAP. The mean square displacement (MSD), relative concentration function (RCP), and radial distribution function (RDF) were used to quantitatively analyse the interface interaction behavior. The research results are as follows: For the AAI, the temperature, the aging level of asphalt, and chemical composition of aggregates will affect the interaction behavior of the AAI. Increasing temperature accelerates the diffusion of asphalt on the surface of aggregate. However, the increase of the aging level of asphalt and the alkalinity of aggregate will decrease the interaction rate of asphalt on the surface of aggregate. For the MAI, the temperature and the ratio of filler-asphalt (RFA) significantly affect the interaction behavior of the MAI. The molecular diffusion rate of matrix asphalt and aged asphalt increases significantly with the increasing temperature. The addition of filler will decrease the diffusion rate of asphalt, and the diffusion rate decreases with the increase of RFA. This article comprehensively and systematically studies and evaluates the effect of various factors on the interface interaction behavior. The results provide guidance for improving the adhesion ability of AAI and enhancing the degree of incorporation of MAI.