Aging of Geomembranes Used in Hydraulic Structures

The waterproofing of dams, canals, and tunnels often has the associated geomembrane submerged in water. When this is the case, air incubation in ovens, and/or under ultraviolet exposure may not adequately address the in-situ aging process. For example, with polyolefins (HDPE, LLDPE and fPP) the depletion of antioxidants proceeds faster in water than in air, yet the oxygen concentration is lower in water than in air. For PVC, the migration of the plasticizers is governed by diffusion and desorption from the surface. Thus, water immersion must be investigated and compared to the more usual ways of incubation of using forced air ovens, and ultraviolet weatherometers. This project addresses the various aging process and presents preliminary information in regard to water immersion.