Observations of the Dimensional Stability of Four GCL Products under Combined Thermal and Moisture Cycles

To investigate the possibility that combined thermal and moisture cycles can cause irrecoverable shrinkage of geosynthetic clay liner (GCL) panels when left exposed in the field, the dimensional stability of four different GCL products were investigated under idealised cycles in the laboratory. A number of variables, including type of GCL, initial moisture content and boundary conditions were examined to assess the effects of these variables on the potential incremental and total shrinkage. Nine samples, involving four different GCL products were tested to investigate whether the specific characteristics of each GCL had an effect on the observed GCL shrinkage. The resulting deformations of the panels were then measured using both hand measurements and digital image correlation techniques. These preliminary results indicate that cyclical shrinkage of GCLs is anisotropic, and that different products shrink at different rates and to different final magnitudes. 1