Investigation of the Surfactant’s Effect on the Physical and Mechanical Properties of Sandy and Clayey Sandy Soils

Due to the development of various industries, surfactants are used in detergents and disinfectants, oil industries, soil washing, petrochemicals, etc., and enter the ground in different ways. Surfactants, after entering the soil composition, change the physical and mechanical properties of soils due to physical and chemical processes. In this study, the pollutant effect of anionic, cationic, and non-ionic surfactants on some properties of sandy and sand with 20% clay soil is investigated. For this purpose, compaction, direct shear, consolidation, and capillary tests were performed on the soil exposed to water with 1% of various surfactants. The results showed that surfactants have a negligible effect on the maximum dry unit weight of the granular soil. Also, Triton and HEC surfactants do not have a significant effect on the optimum moisture content, but other surfactants reduced it compared to water. In general, soil shear resistance decreases in the presence of surfactant solutions compared to clean water. Also, according to the results of consolidation tests performed on the sandy soil with 20% clay, HEC, LABSA, and CTAC surfactants increased the compression coefficient and increased the swelling coefficient compared to clean water. HEC surfactants caused a decrease and CTAC and LABSA surfactants increase the consolidation coefficient (CV) compared to water. Also, all surfactants reduced differently the capillary ascend in the soil.