Hydration of geosynthetic clay liners (GCLs) on compacted zeolite

Abstract

The hydration performance of two geosynthetic clay liners (GCLs) over compacted zeolite is investigated in this paper. Zeolite was chosen as the subsoil because of its greater optimum water content with respect to other natural soils (41%). The water content changes of GCL-1 and GCL-2, which each had distinct properties, were the same until 30 days of hydration. The water content of GCL-1 increased from 120% to 147% after 62 days of hydration and then decreased to 117% after 90 days of hydration. However, the water content of GCL-2 was greater than that of GCL-1 (149% vs. 117%) after 90 days of hydration. The reduction in the water content of GCL-1 after 90 days was due to cation replacement. The exchangeable mole fractions of sodium cations (XNa) decreased whereas exchangeable mole fractions of divalent cations (XCa and XMg) increased with the duration of hydration. Cation replacement was more pronounced for GCL-1 than for GCL-2. Although swell indices decreased markedly with the durations of hydration, the final hydraulic conductivities of GCL-1 and GCL-2 were almost the same, around 2.0 × 10−11 m/s. This means higher water content masked the negative influence of cation replacement, resulting in comparable and low hydraulic conductivities for both GCLs.