Beneficial impact of polymer treatment of Ca-bentonites on long-term hydraulic conductivity

The hydraulic conductivity of geosynthetic clay liners for the confinement of waste disposal facilities mainly depends on the hydraulic conductivity of the core bentonite clay encased between the two geotextiles. Bentonite clay is the most common material for geosynthetic clay liners. Even thought, sodium bentonite has the lowest hydraulic conductivity to water, calcium bentonite is widely used because of low cost and availability. This research concerns the evaluation of the treatment of calcium bentonite with an anionic polymer, sodium carboxy methyl cellulose (Na-CMC) with hyper clay technology. Permeability tests were performed in order to compare hyper clay behaviour to the standard sodium activation treatment of calcium bentonite. Increasing concentrations of calcium dichloride, 5M- 100M - 200 M, were used as hydrating solutions. Test results showed the beneficial effect of the anionic polymer treatment on the hydraulic performance of the clay analysed in the long term