Progress of Multi-scale Research on Chloride Salt Erosion Damage of Asphalt and Asphalt Mixture

In the actual service process of asphalt pavement, it is inevitable to be eroded by chloride salt and multi-factor coupling. The multiphase dispersion compositions of asphalt mixture lead to significant multi-scale characteristics of chloride salt erosion. To clarify the current status of research on the damage multiscale behavior of asphalt and asphalt mixture under chloride salt and multi-factor coupling, the laboratory simulation devices and test schemes of chlorine salt environment were summarized. The salt erosion damage of asphalt, asphalt-aggregate interface system and asphalt mixture at different scales were classified and summarized. The macro-performance, micro-mechanism and meso-behavior of material damage under chloride erosion environment were discussed. Finally, the development direction in multi-scale damage induced by chlorine salt of asphalt and mixture were prospected. It can be found that the chloride salt environment has physical erosion on asphalt, asphalt-aggregate interface and asphalt mixture, the type and concentration of chlorine salt, erosion time and asphalt type will affect it. The multi-factor coupling effect aggravates the salt corrosion process, especially in the salt freezing cycle. However, selecting modified asphalt and mixing with additives can improve its performance. The ion corrosion, the expansion stress of salt crystallization and icing results in the performance degradation of the asphalt mixture. Commonly used laboratory simulation methods of chloride salt environment only consider the single factor of salt or the double factor of salt-temperature, which is inconsistent with the actual working conditions of asphalt pavement subjected to multi-factor coupling. In addition, there is a lack of multi-scale methodology to investigate damage induced by chloride in asphalt mixture from a multi-scale level. It is recommended that further optimize of the laboratory simulation scheme for chloride salt erosion and develop more scientific and accurate test devices. The multi-scale characteristics of salt damage behavior and their relationships at different scales of asphalt and asphalt mixture should be studied, and thus, establish the multi-scale research system of chloride damage in asphalt and asphalt mixture. © 2023 Xi'an Highway University. All rights reserved.