The short-term aging effect on the interface and surface wetting behavior of modified asphalt mixtures

Abstract

In this study, the interface models and nanodroplets wetting models of base asphalt (BA), polyurethane modified asphalt (PU-MA) and polyurethane/graphene oxide composite modified asphalt (PU/GO-MA) with acidic and alkaline aggregates were constructed. The adhesion and debonding effects of modifiers on short-term aged asphalt mixtures were analyzed by molecular dynamics (MD) simulation. The moisture damage resistance of the mixture was evaluated by simulating the wetting characteristics of asphalt and water nanodroplets on the aggregate surface. The contact angle, adhesion work, debonding work and relative concentration distribution can effectively analyse the interface interaction behavior between asphalt and aggregate. The results show that the adsorption effect between aged asphalt and CaCO _3 was stronger, and short-term aging enhanced the interfacial adhesion of asphalt mixtures. Calcite was more hydrophilic, and its resistance to moisture damage was far less than quartz. The difference between the contact angle of water-aggregate and that of asphalt-aggregate can effectively analyze the water sensitivity of asphalt mixture. In addition, different components played different roles in the adsorption of asphalt and different aggregate surfaces. The synergistic analysis of the asphalt-aggregate interface and the asphalt nanodroplet-wetting aggregate surface can more comprehensively reveal the variation principle of asphalt parameters and nanoscale properties of asphalt mixtures.

Keywords

• molecular dynamics
• asphalt-aggregate interface
• contact angle
• short-term aging
• modified asphalt