Effect of salt concentrations on the permeability and compressibility of soil-bentonite mixtures

Abstract

The influence of NaCl and CaCl2 at various concentrations on permeability and compressibility of mixtures of basalt soil and bentonite has been investigated. Comparison of hydraulic conductivity (k) for different salt solutions shows that the divalent cation have more effect than monovalent cation. Comparison of different salt concentrations for a particular salt on a particular soil mixture shows that the k decreases with decreasing salt concentration. This decrease can be attributed to an increase in diffuse double layer thickness. A change in salt concentration from 0 (Deionized Water) to 0.01 molc/L did not produce any significant effect on the k for the basalt soil-bentonite mixture of proportion 100:20, but a further increase in salt concentration had a pronounced effect on k. The compressibility of the soil mixtures was reduced with increasing salt concentration of the pore fluid.