HYDRAULIC CONDUCTIVITY OF GEOSYNTHETIC CLAY LINERS AFTER FREEZE-THAW

Hydraulic conductivity tests were performed in large tanks on intact ( single panel) and overlapped samples of three geosynthetic clay liners (GCLs) that had been subjected to freeze-thaw cycles. The compressive stress applied to the GCLs (7.6-12.4 kPa) was selected to simulate fi nal cover systems for landfills. Laboratory flexible-wall permeameter tests were also performed. With the exception of one overlapped GCL, a ll three GCLs withstood three freeze-thaw cycles without a significant change in hydraulic conductivity. An overlapped, geotextile-encased, stitch-bonded GCL did undergo a 1,000-fold increase in hydraulic condu ctivity after one freeze-thaw cycle, but the overlapped area contained stitches, which are left off the edges of the full-sized material tha t is deployed in the field. In general, the tests showed that GCLs can withstand at least three freeze-thaw cycles without significant chang es in hydraulic conductivity.