Physicochemical mechanisms of asphalt–aggregate interface adhesion: Effects of mineral composition and surface energy

The adhesion and debonding behavior at asphalt–mineral interfaces are controlled by interfacial physicochemical interactions that dictate wetting, adsorption, and moisture susceptibility of these organic–inorganic systems. Although the rheological and colloidal characteristics of asphalt have been widely studied, the influence of mineral surface chemistry and interfacial energetics on adhesion remains insufficiently understood. This study investigated the interfacial adhesion between asphalt and mineral aggregates through a combined experimental and theoretical approach integrating bitumen bond strength (BBS) testing, surface free energy analysis, and zeta potential characterization. Four representative minerals—calcite, dolomite, orthoclase, and quartz—were selected to elucidate the role of mineralogy in interfacial interaction mechanisms. Results show that carbonate minerals (calcite and dolomite) possess higher specific surface areas and more positive surface potentials, enhancing adsorption and electrostatic attraction with asphalt molecules, whereas silicate minerals (orthoclase and quartz) exhibit higher surface polarity and water affinity, leading to moisture-induced debonding. Surface energy calculations further indicate that lower polar and higher dispersive components promote thermodynamically stable adhesion, with calcite exhibiting the smallest adhesion work loss (57.4 %) upon water exposure. These findings advance the understanding of interfacial thermodynamics and charge-mediated adhesion in asphalt–mineral systems and provide fundamental insights for tailoring surface energy and wettability in organic–inorganic composites.