Laboratory investigation of thermally induced desiccation of GCLs in double composite liner systems

The potential for desiccation of GCLs in double composite liner systems under thermal gradients is experimentally investigated. The effects of key initial and boundary conditions such as the GCL mass per unit area, initial GCL and subsoil water content, time lag between waste placement and temperature increase, the applied temperature gradient and the foundation layer thickness are investigated and discussed. The results suggest that surface temperatures of 39–45 °C, corresponding to thermal gradients of 59–67 °C/m, can induce sufficient thermally driven moisture redistribution to cause desiccation of GCLs. For surface temperatures of 29–37 °C and thermal gradients of 20–29 °C/m there was occasional slight cracking observed in about a quarter of the cases examined. Results of laboratory permeability tests on the virgin and exhumed samples are used to assess the self-healing capacity of GCLs.