Comparison of natural, polymer treated, and sodium activated Ca-bentonites

The hydraulic conductivity of geosynthetic clay liners (GCLs) for the confinement of waste disposal facilities depends on the hydraulic conductivity of the bentonite clay encased between the two geotextiles. Sodium bentonites are widely used for GCLs due to their low hydraulic conductivity to water. Although, calcium bentonites (Ca-bentonites) are low cost and readily available, the hydraulic conductivity of calcium bentonites is higher compared to that of sodium bentonites (Na-bentonites). This study compares the impact of the treatment of Ca-bentonite with an anionic polymer, sodium carboxymethyl cellulose (Na-CMC) using HYPER clay technology, relative to standard sodium activation treatment. The swelling ability and hydraulic conductivity to CaCl2 solutions of a natural (untreated) Ca-bentonite was compared to those of sodium activated bentonite and to polymer treated bentonite. Test results showed the superior performance of the polymer treatment compared to sodium activation