Effect of ionic emulsifiers on the properties of emulsified asphalts: An experimental and simulation study

The incorporation of emulsifiers into asphalt binder has significant advantages on decreasing mixing temperature, improving construction environment and saving energy. In this study, the effects of ionic emulsifiers on the service performances of emulsified asphalts were investigated by laboratory experiments and molecular dynamic (MD) simulation. To this aim, cationic stearyl trimethyl ammoium chloride (STAC) and anionic sodium dodecylbenzene sulfonate (SDBS) were selected. The effects of these two ionic emulsifiers on the stability and rheological response of emulsified asphalts were investigated via the surface tension, storage stability and dynamic shear rheology tests. Furthermore, the binary model of emulsifier/asphalt and the ternary model of water/emulsifier/asphalt were constructed, and a series of indices such as interaction energy, roughness, relative concentration distribution, mean square displacement (MSD) were analyzed to explain the performance differences of various emulsified asphalt from molecular perspective. The experimental results showed that the influence of STAC on stability and rheological properties of emulsified asphalt was more considerable by comparison to that of SDBS. The smaller surface tension could be detected for STAC emulsified asphalt considering the stronger hydrophilicity of STAC. Moreover, compared to SDBS, STAC significantly improved the deformation resistance and elastic recovery of emulsified asphalt. It was concluded from MD simulation that the adsorption system formed by STAC was more stable. Both of experimental and simulation results provide insight into understand the contribution of ionic emulsifiers to the stability and rheological properties of emulsified asphalts.