Hydraulic capability of polymer-treated GCLs in saline solutions at elevated temperatures

Geosynthetic clay liners (GCLs) can be used effectively as barriers in waste containment facilities. However, interaction of the GCL with a saline solution might cause a decrease in the hydraulic performance of the GCL. In order to simulate the field conditions, triaxial permeability tests were performed on a GCL permeated with 0.5 M and 0.1 M MgCl2 solutions at 20 °C, 40 °C and 60 °C. The temperature increase resulted in an increase in the permeability of the GCL and this increase is attributed to a decrease in the viscosity of the permeant fluid. In order to improve the hydraulic capability of the GCL, an anionic and a cationic polymer with a polymer content of 1% and 2% by mass in the bentonite-polymer mixture was added to the GCL. According to the results, polymer treatment caused up to two orders of magnitude decrease in permeability and improved the hydraulic capability of the GCL. Generally, anionic polymer treatment resulted in slightly lower permeabilities than cationic polymer treatment. Furthermore, 2% anionic polymer treatment caused almost no decrease in permittivity when compared with 1% polymer treatment. However, the permeability of 1% cationic polymer-treated GCL was the lowest among all the other anionic and cationic polymer-treated GCLs that were permeated with 0.1 MgCl2 solution at 60 °C.