GCL self-healing: fully penetrating hole/slit hydrated with RO water and 10 mM Ca solution

Abstract

The self-healing of fully penetrating artificial defects (circular holes and rectangular slits) in geosynthetic clay liners (GCLs) on full hydration in deionized water and 10 mM calcium chloride (CaCl2) solution under 2 kPa overburden stress are compared. Circular holes with diameters up to 41 mm self-healed in deionized water but with an indentation of about up to 2 mm deep remaining at the center of the larger self-healed zones for holes of 30 mm diameter and larger. Holes of up to 35 mm diameter completely closed-up in 10 mM CaCl2 solution, but with an indentation of about up to 6 mm deep remaining at the center of the larger self-healed zones for holes of 30 mm diameter and larger. A fully penetrating 15 mm wide × 120 mm long single slit in the center of a GCL specimen completely closed up in deionized water but not in 10 mM CaCl2 solution. Even in deionized water, the slit does not fully close when 25 mm (or more) wide. Double parallel silts 15 mm wide × 240 mm long closed up in deionized water, but not in 10 mM CaCl2 solution when there was a 20 mm-wide strip of undamaged GCL between the slits, but did not fully close up when the undamaged GCL strip between the slits was reduced to 10 mm or 5 mm. The difference in self-healing based on the hydrating fluid chemistry is discussed.