Interface interaction between high viscosity asphalt and aggregate: A multi-scale study based on experiments and molecular dynamics simulation

The pull-off strength, boiling peeling ratio, adhesion work, stripping work, interaction energy, nanoindentation resistance force, and hydrogen bond distribution were analyzed based on laboratory tests and molecular dynamics simulation. The interface interaction between the original, aged, or regenerated high-viscosity asphalt (HVA) and the acid or alkali aggregate component in the aqueous or anhydrous environment was clarified from multi-scales of macro, micro, and nano scales. The results show that the pulling strength has an obvious positive correlation with the interfacial adhesion work, which can evaluate the interfacial adhesion state with water. The boiling peeling ratio has an obvious positive correlation with the interface stripping work, which can evaluate the interfacial adhesion state without water. The ratio of adhesion work to stripping work can characterize the interface water-stripping resistance. In nanoindentation simulation, the vertical resistance force of the indenter characterizes the interaction between HVA and the aggregate indenter. The interfacial adhesion state deteriorates with the deepening of HVA aging. Further addition of a high viscosity modifier (HVM) in the regenerated HVA effectively restores the interfacial adhesion state. The higher temperature causes worse interfacial adhesion, and the hydrogen bond ratio, adhesion, and water-stripping resistance of the interface between the HVA and alkaline aggregate components are much better than those between the HVA and acid aggregate components. Van der Waals force plays a leading role in interfacial adhesion. With the deepening of aging, the oxygen-containing functional groups such as carbonyl and sulfoxide in HVA increase, in which it is easy for oxygen atoms to form hydrogen bonds with water, so the water-stripping resistance of the interface decreases.