Effect of Ionic Emulsifiers on the Stability of Emulsified Asphalt Based on Molecular Dynamics Simulation

Abstract

To investigate the effects of ionic emulsifiers on the stabilization of emulsified asphalt, this paper used the Materials Studio software package to model a two-layer structure consisting of asphalt-emulsifier-water-emulsifier-asphalt. The principles of molecular dynamics were used to simulate the emulsified asphalt solution with various types of ionic emulsifier molecules. The effects of the anionic (SDS)/cationic (CTAB) emulsifiers on the stability of the emulsified asphalt were studied and compared. The following performance metrics were investigated: the interfacial monolayer morphology of the emulsifier molecules; the interaction energy between the emulsifier molecules and the water molecules; and the interaction energy between the emulsifier molecules and the asphalt phase/water phase. The results showed that, compared with CTAB emulsifier molecules, SDS emulsifier molecules had a higher extent of aggregation in the emulsified asphalt model system. The binding ability between the SDS emulsifier and the water molecules was stronger than that of the CTAB emulsifier molecules and negatively affects the stability of emulsified asphalt. Compared with the CTAB emulsified asphalt system, the SDS emulsified asphalt system has higher binding energy. In general, the stability of the CTAB-emulsified asphalt system is better than that of the SDS-emulsified asphalt system.