Geosynthetic Clay Liners Subjected to Differential Settlement

Geosynthetic clay liners (GCLs), which consist of a thin layer of bentonite attached to one or more geosynthetic materials, are receiving increased use as low-permeability barrier layers in waste-containment systems. Tests were performed in tanks to measure the hydraulic conductivity of GCLs that were subjected to differential settlement. In most cases the GCLs maintained a hydraulic conductivity of 1 × 10−7 cm/s or less when subjected to tensile strains of 1–>10%, depending on the material and test conditions. Overlapped GCL panels maintained their hydraulic integrity despite in-plane slippage of up to 25–100 mm. In general, the ability of GCLs to withstand differential settlement appears to be greater than that of compacted clay liners, but less than that of geomembranes. GCLs are a promising barrier material for situations in which differential settlement is expected, for example, in landfill final covers.