Monitoring of Pollutant Diffusion into Clay Liners by Electrical Methods

A non-destructive test was carried out on a liner material—sand bentonite mixture (SB) with a continuous concentration diffusion of NaCl electrolyte. The work reported studied the spacio-temporal variation of the electrical conductivity $\sigma ^{*}_{\mathrm{s}}$ (z, t) in a diffusion soil column with different heights. A relationship between the interstitial pore fluid concentration of SB and the electrical conductivity of the solution has been established by mixing and compacting samples of sand bentonite with NaCl electrolytes at different concentrations. Electrical conductivity of compacted specimens was measured with a two-electrode cell. The conductivity measurements were used to quantify the pore fluid concentration and effective diffusion coefficient of SB liners. It is concluded here that the electrical conductivity of compacted specimens depends mainly on the salt concentration in the pore fluid and it could be used to measure ionic movement through liners during diffusion. The experimental diffusion coefficient reached theoretical diffusion coefficient when sample height is equal to 40 cm.