Comprehensive analysis on influences of aggregate, asphalt and moisture on interfacial adhesion of aggregate-asphalt system

This study aims to investigate the effects and contributions of different factors, including aggregate source and shape, asphalt type and aging, and moisture condition, on the interfacial adhesion of aggregate-asphalt system. Self-developed spherical aggregates were used to control the variable, and a quantifiable boiling test was proposed to conduct on various conditions. Properties and shape of mineral aggregates and surface free energies of asphalt binders were characterized and further correlated to the interfacial adhesion. In addition, the effect of moisture within aggregate on the adhesion was studied. By the multiple regression analysis, contributions of these factors to the adhesion were discussed. Results indicate that quantifiable boiling test was able to quantitatively evaluate the adhesion of aggregate-asphalt. Not only the aggregate source but also its shape had a significant influence on the interfacial adhesion. The more cubical the aggregate, the higher the value of the bonding ratio. Modified asphalt exhibited better adhesion with mineral aggregate owing to its high surface energy. Short-term aging was conducive to improving the adhesion of asphalt, whereas long-term aging had the opposite effect. Without regard to moisture condition, the aggregate source had a significant influence on the interfacial adhesion, followed by asphalt aging, aggregate shape and asphalt type.