Assessment of the stress crack resistance of multilayered textured HDPE geomembranes

The stress crack resistance (SCR) of different multilayered textured geomembranes (GMBs) immersed in synthetic municipal solid waste leachate at 55°C and 85°C for 50 months was assessed using their smooth edge or smooth equivalent GMBs made from the same formulation as textured GMBs. The difference between the actual thickness of the smooth edge and the nominal thickness of the GMB was shown to result in SCR values that do not reflect the true SCR of the GMB resin when assessed based on the current ASTM standard test procedure. As such, adjustments to the current test method are presented to limit its effect on SCR, especially when comparing the performance of different GMBs based on SCR. Additionally, due to variations in formulation and thickness of the textured and smooth portions of GMB rolls, a new double-notching technique was examined to assess the SCR of the textured portion. Using this technique on samples from textured and smooth portions at different incubation times showed similar initial and stabilised SCR values but different SCR degradation rates for the two different parts of the same GMB roll. Relying solely on SCR values obtained from the smooth edge/smooth equivalent GMB may thus underestimate or overestimate the degradation of multilayered textured GMBs.