Comparison between the beneficial impact of polymer treatment and sodium-activation on calcium bentonites

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 though 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 CarboxyMethyl 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, 5 mM – 100 mM – 200 mM, 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.