Surface and Interface of Fine Aggregate Mixture under the Condition of UV-Ageing and Moisture-Treatment

Abstract

Three-dimensional depth of field microscope (3-D FM), scanning electronic microscope (SEM) and molecular dynamic simulation (MD) were used to evaluate the surface morphology, behaviors and failure mechanisms of mortar and fine aggregate mixture (FAM). The effects of ultraviolet (UV) light and moisture for FAM, the interfacial behaviors of bitumen-aggregate were investigated. Results showed that in the pure mortar, the UV-ageing could increase the adhesion between the bitumen and fine aggregates, and the cohesion failure was dominant after UV-ageing. Due to the lower air voids in the pure mortar, the moisture did not cause the adhesion failure. The molecular dynamic simulation implied that UV ageing and moisture-treatment could reduce the interfacial energy, and the aromatic and asphaltene played a great role in the adhesion between bitumen and aggregate.