Comparison of the Hydraulic Conductivity of GCLs with That of Bentonitic Mixtures

This study discusses and compares the hydraulic conductivities of GCLs to those of sand-bentonit mixtures (SBMs)/zeolite-bentonite mixtures (ZBMs). ZBMs had 20% and 30%, whereas SBM had 20% bentonite contents. The effective stress applied on GCLs was greater than bentonitic mixtures. Neither GCLs nor bentonitic mixtures were prehydrated with water. The results showed that hydraulic conductivities of non-prehydrated GCLs were significantly greater than those of ZBMs and SBMs. Applying greater effective stress did not reduce the hydraulic conductivities of GCLs. Although bentonitic mixtures were non-prehydrated during hydraulic conductivity tests, they had been hydrated with water before compaction. In order to figure out this condition and to make better comparison between the hydraulic conductivities of GCLs and bentonitic mixtures, two brand new GCLs were prehydrated with DI water (DIW). Then, permeation was begun with DIW until one pore volume of flow was passed through the samples. Finally, the permeant was switched to landfill leachate and hydraulic conductivities were determined. The results showed that initial permeation of GCLs with DIW decreased the hydraulic conductivity when GCLs were further permeated with landfill leachates. Also, the hydraulic conductivities of GCLs were less than those of bentonitic mixtures. This may be attributed to greater effective stress applied on GCLs.