Investigating the deterioration mechanism of adhesion between asphalt and aggregate interface under acid rain erosion

Abstract

To further reveal the effect of acid rain on the interfacial adhesion of asphalt mixtures, molecular dynamics (MD) simulation was used to investigate the interfacial damage mechanism. A water layer containing hydrogen ions, sulfate ions, and nitrate ions was inserted between the asphalt and aggregate to simulate the effect of acid rain attack on the interface. The interfacial bonding strength under three conditions of dry, pure and acidic water was analyzed. The effect of acidic ions on the spatial arrangement and movement of asphalt molecules was discussed. The damage of the asphalt-aggregate interface under both pure water and acidic water attack was investigated. The results showed that the acidic ions promote the rearrangement distribution of asphalt molecules at the interface, reduce the concentration of asphalt molecules at the interface, and weaken the adhesion ability at the interface. The degree of aggregation of polar components increases, resulting in a reduction in the movement migration capacity of asphalt and poor mobility, increasing the possibility of asphalt stripping from the aggregate surface. Under the influence of acidic ions, less separation energy is required for interfacial adhesion damage to occur between asphalt and aggregate, and the amount of deformation at interfacial failure is smaller.