Swelling Pressure of Compacted Clay Liners Contaminated with Inorganic Salt Solutions

Processed and natural clays are widely used to create impermeable liners in solid waste disposal landfills. Swelling pressure and hydraulic conductivity of clay liners can be significantly affected by the leachate from the waste mass. In this study, the effect of five different inorganic salt solutions on the swelling pressure of compacted clay liners was experimentally investigated. As contamination liquids, sodium chloride (NaCl), ammonium chloride (NH(4)Cl), potassium chloride (KCl), calcium dichloride (CaCl(2)), and iron trichloride (FeCl(3)) inorganic salt solutions were used at concentrations of 0.01, 0.10, 0.25, 0.50, 0.75, and 1 M. The swelling pressure tests were conducted after permeation of salt solutions was completed on low-plasticity (CL class) and high-plasticity (CH class) compacted clays. The experimental test results indicated that the effect of inorganic salt solutions on CL (chlorite-smectite) clay samples was different from that on CH (smectite) clay samples. The swelling pressures were found to increase when the salt concentrations increased for contaminated CL clay samples. On the other hand, with increasing salt concentrations, the swelling pressures decreased for the contaminated CH clay samples.