Evaluation of the Hydration Method of Geosynthetic Clay Liners in View of Subsoil Conditions

Presented study compares two hydration methods for geosynthetic clay liners (GCL) which were conducted through flexible-wall permeameters. In this study, GCLs were hydrated over silty sand and zeolite subsoils. At the end of the hydration durations, bentonite water contents from the control sample method (CSM) that uses two permeameters and the single large sample method (SLSM) that uses one permeameter were compared. There are 8% and 20% differences between the final bentonite water contents obtained from two methods when silty sand and zeolite were used as subsoil, respectively. Regardless of the hydration method used, bentonite water content of GCL hydrated over zeolite was two times greater than that of GCL hydrated over silty sand (similar to 125% and 65%). In addition, subsoil water content profiles along silty sand and zeolite were quite similar. Although the final hydraulic conductivities of the GCLs hydrated with CSM and SLSM were almost the same, the hydraulic behaviors were different. This difference was caused by the water uptake of GCLs during the hydraulic conductivity tests. In contrast, although swelling of bentonite particles can be monitored more easily in CSM, this method is more expensive and troublesome than SLSM as it requires two parameameters and compacted specimens