Effects of Temperature Increase in 0.5 M MgCl2 Solution on Hydraulic Capability of Anionic Polymer-Treated Geosynthetic Clay Liners Used as Barriers

Geosynthetic clay liner (GCL) is a lining material that consists of a bentonite layer sandwiched between two geotextiles. To simulate the interaction between an aqueous solution and a barrier material, triaxial permeability and free swell tests are performed on a GCL that is permeated with 0.5 M MgCl2 solution. The temperature of the solution is 20, 40, and 60 degrees C, with 0.5, 1, and 2% anionic polymer by mass added to the GCL. Test results indicate that although temperature increase causes a slight increase in the swell index of the GCL, it results in a significant increase of up to 2 orders of magnitude in permittivity. The GCLs are also tested with deionized water. The increase in permittivity is attributed to a decrease in the viscosity of the permeation fluid. Adding 1% anionic polymer to the GCL results in almost 2 orders of magnitude decrease in permittivity. Anionic polymer-treated GCLs can be used effectively in aggressive MgCl2 solutions by both decreasing the permittivity and increasing the swell index of the GCLs.