Effects of composite geometric characteristics of coarse particles on interface interactions of aggregate-asphalt system

Abstract

The complex geometric morphologies and contact status of aggregate particles and the interface interactions between aggregate and asphalt significantly affect the compaction properties and mechanical response of asphalt mixtures. The spreading-combination method was proposed to build the calculation model of composite geometric indexes to quantitatively characterize the composite geometric characteristics of the particle system. The effects of composite geometric characteristics on the interface interactions of the aggregate-asphalt system were analyzed adopting the contact-slip tester. The results indicate that the measures of shape, texture, and angularity respectively denote perimeter, surface area, and volume. The composite shape index is primarily affected by the number of particles. Smaller-sized coarse aggregates and fine aggregates exercise a greater impact on the composite texture index, while the composite angularity index is more sensitive to large-sized coarse aggregates. The fine particles attach to the surface of coarse aggregates, diminishing the contributions of the composite texture characteristics of coarse aggregates to the particle contact strength of the particle system. The larger the composite angularity index, the more significant the lubricating effect of asphalt on particle contact. However, asphalt can transform a part of the interference effect of the fine aggregates into the bonding effect of the skeleton. The composite angularity index is positively correlated with the skeleton bonding index, which can be used to evaluate and predict the interface interactions of the aggregate-asphalt system.