Effect of dynamic water pressure on the adhesion behavior of recycled asphalt-aggregate interface by molecular dynamics method

Abstract

The integrity of the asphalt-aggregate interface is challenged by the dynamic water pressure under traffic loads, especially for recycled asphalt mixtures that represent lower moisture damage resistance by comparing with virgin asphalt mixtures. The effect of dynamic water pressure on the microscale interfacial adhesion properties between the waste-oil recycled asphalt and aggregate was comprehensively investigated based on the molecular dynamic simulation. The molecular models of recycled asphalt and aggregate were calibrated based on the chemical and physical analysis in experiments. The interfacial contact models between recycled asphalt with different regenerants (waste cooking oil-WCO, waste vegetable oil-WVO, and waste engine oil-WEO) and basalt aggregate were established, which also incorporated the thermodynamic process of water intrusion into the interface. The interface behaviors were studied by analyzing the cohesion energy of asphalt, the adhesion energy of interface, and the distribution of asphalt and water concentration on the aggregate surface. The results demonstrated that the dynamic water pressure can accelerate the water to penetrate the asphalt film. The recycled asphalt was pushed away from the basalt aggregate surface after the water film was formed at the interface, where the four components of asphalt leave the interface at different rates. Compared with the other two kinds of waste-oil recycled asphalt and conventional recycled asphalt, the WEO recycled asphalt-aggregate interface represented the optimum moisture damage resistance. The decrease of interface adhesion energy is about 55.7 % subjected to the coupling effects of the high-temperature and dynamic water pressure at 0.5 MPa.