Erosion mechanism of sea salt solution on the performance of SBS-modified asphalt mixtures

Investigation of the erosion mechanism of sea salt solution on properties of asphalt pavement has important implications for the perpetual asphalt pavement construction in the coastal region. This paper intends to explore the performance deterioration mechanism of styrene-butadiene-styrene (SBS)-modified asphalt and mixture eroded by sea salt. The mixed sea salt solutions were prepared, and salt erosion dry-wet and freeze-thaw cycle tests were conducted for the simulation of the sea salt erosion environment. Multiple stress creep recovery (MSCR) tests, force-ductility tests (FDT), splitting tests and mass accumulation analysis were executed to study the performance deterioration mechanism of asphalt binder and asphalt mixture. The results indicate that the elastic recovery, high-temperature permanent deformation, rutting resistance and stress sensitivity of asphalt were improved after sea salt erosion, which proved the improvement of high-temperature rheological properties, while the stability of asphalt binder was damaged. Moreover, the low-temperature crack resistance of asphalt binder was significantly damaged. Meanwhile, the mass accumulation rate of asphalt mixture eroded by sea salt increased, indicating that the salt migrated into asphalt mixture specimens in mixed salt solution after sea salt erosion, which was also confirmed by the appearance of salt crystallisation phenomenon and the observation results of frost. Therefore, the splitting tensile strength and splitting tensile strength ratio (TSR) of the asphalt mixture specimens were reduced, resulting in serious damage to moisture stability. Finally, it is confirmed that the concentration of the mixed salt solution and the number of cycles exerted a significant effect on the properties of the asphalt and asphalt mixture.