Addressing loess salinisation is a crucial element in preserving ecological stability and fostering sustainable development in the northwest Loess Plateau. To investigate the impacts of salt solution on the properties of loess, independently designed salt solution-loess dynamic cyclic erosion equipment was used to soak the loess. Then, numerous tests were performed to analyse the variability of the effects of salt solution concentrations (SSC) and type, as well as the duration of soaking time, on these physico-mechanical properties. The results demonstrated that after being soaked in two different types of salt solutions for 3 days, the shear strength index of loess preliminary decreased and then increased. The compressibility preliminary increased and then declined when the SSC increased. After a 7-day soaking period, the cohesion of the loess did not change considerably, whereas the internal friction angle increased in proportion to the SSC. The compression of loess tended to initially decrease, subsequently increase, and eventually decrease. Loess can be slowed down in its disintegration process by salt solution, and disintegration duration can be effectively shortened with a prolonged soaking time. Finally, it is examined the evolutionary process of the impact of salt solution on loess microstructure. Moreover, the exchange of clay minerals with iron and aluminium ions is proposed to be the key element determining the water-loess chemical interaction. This study may function as an insightful guide for preventing and treating salinised loess on the Loess Plateau of Northwest China, while also serving as a reference for similar areas worldwide.

The mechanical properties of loess are strongly dependent on the environment where it is deposited. To investigate the effects of acidic, alkaline, and saline environments on the strength and deformation properties of compacted loess, the consolidation test and direct shear test were carried out on loess samples contaminated with different concentrations of acetic acid, sodium hydroxide, and sodium sulfate. In addition, changes in zeta potential, mineralogy, chemical composition, and microstructure of the loess samples at different chemical environments were also measured. The results show that the reduction in the thickness of the diffuse double layer for the loess contaminated with acetic acid leads to the aggregation of clay particles, laying the foundation for the expansion of loess pores, while the dissolution of carbonate cement and chemical cement makes the soil structure looser. Hence, the compacted loess has significantly lower shear strength and higher compressibility in an acidic environment. The mechanical properties in the saline environment show similar variation characteristics to the acidic environment, but this is mainly due to carbonate solubilization. In the alkaline environment, the degree of interparticle cementation of the loess is enhanced by the generation of calcite due to dedolomitization and the generation of colloidal flocs of Al(OH)3, Fe(OH)3, and H2SiO3. In addition, the pore connectivity is greatly reduced by the extensive distribution of clay particles caused by the development of a diffuse double layer. As a result, its compressibility and shear strength are improved compared to uncontaminated loess. These findings can be used as a reference for geoengineering practice in loess areas.