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 x 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.