Rate-dependent interfacial adhesive strength and toughness between aggregates and modified asphalt binders in ambient conditions

• Verified the adhesion between aggregates and asphalt binders through combined simulation and experimental studies. • Elucidated effects of loading rates on the adhesive strength and toughness between aggregates and asphalt binders via molecular simulation . • Illustrated the microstructure and potential energy surface of aggregates and asphalt binders. Interfacial mechanical behavior was crucial for asphalt mixture performance. This study investigated the rate-dependent interfacial adhesive strength and toughness between aggregates and modified asphalt binders in ambient conditions via combined molecular simulation and experiments. Alumina, silica and calcium carbonate were selected to represent the primary mineral aggregates. Saturate, aromatic, resin and asphaltene were selected to represent the primary components in asphalt binders. Three modifiers, i.e. Styrene-Butadiene-Styrene, Styrene-Butadiene Rubber, and Polyphosphoric Acid, were added into two virgin binders, i.e. PG 64-22 and PG 58-22. Predictions from molecular models were validated by measurements obtained from particle probe scanning force microscopy. It was revealed that adhesion between alumina and binders exceeded the counterparts between silica or calcite and binders of which Van der Waals contributed primarily (>75 %) to aggregate-binder adhesion. Subsequently, aggregate-binder interfaces were probed by molecular electrostatic potentials, diffusion coefficients, radii of gyration, spatial distributions and interfacial morphologies. Furthermore, rate-dependent adhesive strength and toughness were investigated for various aggregate-binder interfaces. The low-speed (<100 m/s), transition (100–300 m/s), and high-speed (>300 m/s) regions were identified from the delamination between aggregates and binders, through which the correlation between interfacial adhesive strength and toughness were established.