Study on the structure and strength characteristics of loess under the action of sodium sulfate

In recent years, with the increasing frequency of human engineering activities, the phenomenon of sodium sulfate erosion has been widely observed in the Loess Plateau. This not only leads to difficulties in land reclamation but also affects human health, posing a significant risk to the investment environment in the Northwest region of China. In this study, three types of loess were treated with sodium sulfate to prepare remolded soil samples with salt content levels of 0%, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5%. Observations and tests were conducted at multiple scales. The results indicate significant differences in the structural characteristics of the three types of loess under the influence of sodium sulfate. The higher the salt content in the loess, the greater the degree of structural damage. Subsequently, macroscopic mechanical properties were determined through direct shear tests, and it was found that as the salt content in the loess increased, the strength decreased. The resulting macroscopic mechanical properties showed a strong correlation with the microstructural characteristics. This study provides valuable insights for soil and water conservation and geological disaster prevention in the Loess Plateau region.