The effect of sea salt solution erosion on cohesion, chemical and rheological properties of SBS modified asphalt

Abstract

This paper aims to explore the damage mechanism of asphalt under sea salt erosion environment from the aspects of surface physics, chemistry, and rheology. To simulate the sea salt erosion environment, styrene–butadiene–styrene (SBS) modified asphalt samples were soaked with mixed salt solutions containing sodium chloride (NaCl) and sodium sulphate (Na2SO4) at six different concentrations. The effect of sea salt solution erosion on cohesion, chemical and rheological properties of SBS modified asphalt was studied through surface free energy (SFE) test, Fourier transform infrared spectroscopy (FTIR) analysis and Dynamic Shear Rheometer (DSR) test, respectively. The results indicate that the salt in the mixed salt solution migrates into the asphalt samples, resulting in the decrease of the total SFE, cohesion work. While the appearance of the new absorption peaks and the changes of peak area ratio of characteristic peaks indicate that the salt migrates into the asphalt sample, reacts with the asphalt, and leads to the aging of asphalt simultaneously. Besides, the viscous component of asphalt decreases, while the elastic component and the Superpave rutting parameter increase, indicating that elastic recovery ability and rutting resistance of the SBS modified asphalt are enhanced. Moreover, the changes of phase angle and complex modulus of rheological master curves at low frequency domain, as well as the increase of failure temperature and the Glover-Rowe parameter, indicate that the high temperature properties of asphalt are improved, while the cracking resistance is damaged. Finally, all the above indexes have linear relationships with the concentration of mixed salt solution.