Microwave-Assisted Magnesium Sulphate for Emulsified Asphalt Demulsification Accelerating and Hydrophobicity Improvement

Abstract

Due to the laying process of the asphalt mixture, the internal water of the asphalt mixture is difficult to evaporate, severely affecting the rapid opening of the road. Moreover, water damage is the most destructive disease of asphalt pavement. This work studies the mechanism of microwave-assisted demulsification of emulsified asphalt under the action of MgSO4 and the effect of adding MgSO4 on the hydrophobic properties of emulsified asphalt to solve the above problem. This work compared the demulsification effect of MgSO4 used, microwave, or the demulsification effect of microwave-assisted MgSO4 on emulsified asphalt. It found by ultraviolet–visible (UV–Vis) spectrophotometer test that compared with microwave 0s, the absorbency values of emulsified asphalt added to 0% and 1.83% MgSO4 solution after microwave 25s decreased from 0.58Abs to 0.53Abs and 0.60Abs to 0.43Abs, respectively. Suggesting microwaves significantly influenced the emulsified asphalt without MgSO4 through the Zeta potential. The Zeta potential value decreased from 10.32mV to -22.21mV when microwaved for 25s. Aggregating of asphalt particles was difficult, confirming that the synergistic effect of microwave and MgSO4 significantly improved the demulsification effect and prevented re-emulsification. The influence of hydrophobicity of asphalt binder was analyzed undergone the contact angle test and X-ray photoelectron spectroscopy (XPS), and the results showed that the contact angle of asphalt binder with water increased from 86.63° to 100.44°, and the chemical composition of the asphalt binder interface changed significantly after the addition of MgSO4.

Keywords: microwave-assisted, MgSO4, demulsification, hydrophobicity