Effect of phenyl functional group on the demulsification process of dodecyl anion emulsified asphalt

Abstract

The demulsification of emulsified asphalt is required to form the adhesion of the asphalt. Using conductivity experiments and validated molecular dynamics simulations, this paper investigated the micro-mechanism of the demulsification process of emulsified asphalt. The results show that the phenyl functional group causes a decrease in the diffusion coefficient of the SiO2 aggregate system and an increase in its interfacial energy, whereas an inverse tendency occurs in the CaCO3 aggregate system, which significantly affects the demulsification rate and adhesion between the emulsified asphalt and aggregates. The electrostatic force between Na+ and CaCO3 allows the emulsifiers to adsorb well to the aggregates, and the demulsification time can be controlled by adjusting the relative content of phenyl functional groups and Na+. The adsorption rate and the adsorption amount of dodecyl anion emulsified asphalt on the aggregate surface grow with increasing phenyl functional group content, leading to a faster demulsification rate of the system and enabling the demulsification rate of the SiO2 emulsified asphalt system to be greater than that of the CaCO3 system. This research demonstrates that the demulsification process of emulsified asphalt can potentially be adjusted by managing the relative content of Na+ and phenyl functional groups in the emulsifier, which gives critical insight into improving the design and construction of asphalt pavements.