Analysis of foaming mechanism and adhesion of foam rubberised asphalt from the perspective of molecular scale

Abstract

ABSTRACT Rubberised asphalt faces challenges such as viscosity and construction energy consumption. These problems can be ameliorated by the use of foaming technology. However, existing studies lack a microscopic-level understanding of the foaming mechanism and interfacial properties of foam rubberised asphalt. Therefore, this study used molecular dynamics simulation methods to establish foam rubberised asphalt models and interface models. The models were analysed from the aspects of model density, energy change, molecular agglomeration behaviour and adhesion work. Results revealed that increased temperature and water consumption caused difficulties in the volumetric compression of the model. The diffusion and aggregation behaviour of water molecules altered the distribution of other molecules in the model, effectively reducing the viscosity of the rubberised asphalt without affecting the chemical structure. In the interfacial model, water molecules contribute to the migration of asphalt molecules to the mineral surface, which exists in two forms: aggregating within asphalt and diffusing to the interface. The interface water molecules enhance the electrostatic interaction between asphalt and minerals. However, due to the random nature of water molecule diffusion, it is difficult to form a regular layer of water molecules at the interface, which leads to failure of the adhesion work.