Permeability of Damaged Geosynthetic Clay Liners

The results of an experimental test program for the permeability of a damaged, adhesive-bonded, geosynthetic clay liner (GCL) are presented. GCL specimens were damaged to simulate damage occurring during handling or installation. Either a portion of the GCL was removed to simulate tearing with bentonite loss, or the GCL was punctured with a metal object to simulate damage without bentonite loss. In general, positive results were obtained for the case of damage with bentonite loss: holes up to 3 cm in diameter self-healed with only a slight increase in hydraulic conductivity compared to an intact GCL. However, the self-healing process can be compromised if torn GCLs with bentonite loss are placed on a coarse subgrade with large pore openings, which allows the bentonite to migrate from the puncture in the GCL. Damage without bentonite loss was simulated for both hydrated and unhydrated GCL specimens. Complete self-healing of punctures was generally obtained, but it was also shown that the conversion of sodium bentonite to calcium bentonite causes a drastic reduction of the self-healing capacity of the GCL, confirming that ion exchange is particularly harmful to the overall performance of GCLs.