Microscopic Analysis of Aging Effects on the Adhesion Properties between Asphalt and Mineral Aggregate

Abstract

This research investigated the effect of aging on the adhesion properties between asphalt and aggregate at the molecular level. Based on the molecular dynamics simulation method, the adhesion characteristics of asphalt component representative molecules and bulk asphalt with silica mineral aggregate before and after aging were evaluated in terms of adsorption energy and adhesion work, respectively. In addition, the simulation results were verified using a pull-off test. Results show that the adsorption energy increases after aging, and was most pronounced for the representative molecules of the asphaltene component. In bulk asphalt, the increase of large-mass molecules after aging led to an increase in its adhesion to mineral aggregate. The presence of water greatly weakened the adhesion strength between asphalt and mineral aggregate, and the negative effect of water on the adhesion strength between aged asphalt and mineral aggregate was severer. The pull-off test confirmed that aging enhanced the adhesion strength between asphalt and aggregate, but exacerbated the negative impact of water on the adhesion strength between asphalt and aggregate. The findings promote further understanding of the effect of aging on the adhesion properties of asphalt to mineral aggregate and the water damage mechanism of asphalt mixtures.