Impact of inorganic components of leachate on mechanical properties of soil: experimental study and statistical analysis by response surface methodology (RSM)

Besides saltwater intrusion and other soil salinity sources, landfill leachate with high electric conductivity and salinity is one factor affecting the geotechnical properties of soil. This study intended to investigate the behavior of clayey sands in interaction with three common salts in landfill leachate (NaCl, CaCl 2 , AlCl 3 ). A classic test design plan for a single salt solution was done with salt content ranging from 0 to 2% by dry soil weight. Results showed that the salts increased shear strength and, especially, AlCl 3 that had the highest effect. In addition, response surface methodology (RSM) was used to model this phenomenon statistically. RSM results confirmed the outcomes of the classic design. Moreover, RSM showed that in multi-salt soil, AlCl 3 controlled the changes in the soil properties. The sample with salt contents of 1.875% (AlCl 3 ), 0.89% (CaCl 2 ), and 0.02% (NaCl) was selected as the optimum content based on the maximum soil strength. Moreover, salinity reduced the liquid limit and plastic limit by 47% and 57%, respectively. Also, the optimum moisture content and maximum dry density were decreased due to the salinity.