Hydraulic conductivity of geosynthetic clay liners permeated at elevated temperatures

The environmental performance of landfill liners is primarily controlled by the fate and transport of leachate constituents from the landfill leachate. Hence, hydraulic conductivity of the liner is a key factor when selecting material for lining systems. Hydraulic conductivity is influenced not only by the properties of the porous media but also the permeant liquid. There are many studies where elevated temperatures of waste and leachate have been reported due to the aerobic decomposition of the organic fraction of waste. At elevated temperatures, soil structure and permeant viscosity change. However, there is very little experimental data on hydraulic conductivity of clays or geosynthetic clay liners (GCLs) permeated at elevated temperatures.; The primary objective of this study was to evaluate the effect of elevated permeant temperature on hydraulic conductivity of GCLs. An experimental setup was designed to meet the research objectives. The key conclusions are: (1) There is a 2 to 3 fold increase in the hydraulic conductivity of GCLs when permeated with DI water, tap water, or 0.1 M CaCl2 solutions at 80 °C when compared at 21 °C; and (2) this increase in hydraulic conductivity is primarily due to decrease in the viscosity of the permeant. Hence, hydraulic conductivity of GCLs at elevated permeant temperature can be estimated by applying the viscosity correction specified in ASTM D 5084 to the hydraulic conductivity measured at a room temperature.