Self-healing capacity of GCLs under simulated field conditions

Abstract

The self-healing capacities of a GCL with natural bentonite (NB) as core (NB-GCL) and a GCL with a polymerized bentonite (PB) as core (PB-GCL) were investigated under simulated field conditions, i.e. geomembrane-GCL-a clayey subsoil layer composite liner system with a damage hole on the geomembrane and the GCL. The clayey subsoils tested had initial water contents of 22.2% and 26.8%. The liquids used were deionized (DI) water and 0.3 M NaCl solution. The test results indicate that for both the PB-GCL and NB-GCL only hydrated on the subsoils for 1–3 months, a damage hole of 15 mm in diameter was almost not self-healed. For cases of applying a constant liquid head on the top of the geomembrane of 100 mm, the sizes of damage holes were self-healed in term of diameter is about half of the values reported in the literature for tests with plenty liquid supply to the damaged GCLs. Further, for the conditions tested and for the cases self-healed, DI water leaked into the subsoil was less than about 60 g, and 0.3 M NaCl solution leaked was less than 150 g.