New GSI method for strain hardening of HDPE geomembranes

April 1st, 2022

Traditionally, high-density polyethylene (HDPE) geomembranes are checked for stress crack resistance using the ASTM D5397 single point-notched constant tensile load (SP-NCTL) test (Hsuan, Lord and Koerner [1990]). This test uses notched specimens, surfactant, and elevated temperatures to accelerate the behavior and force a brittle failure in HDPE geomembranes. With today’s high stress crack resistant HDPE […]

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Measuring strain in geosynthetics

October 1st, 2021

Q: Currently, what is the best-known method to measure strains in geosynthetics? We are having arguments between results generated from crosshead movement and extensometers. A: This question arises often when comparing ISO 527/ASTM D638 and ASTM D6693 results. The former requires an extensometer, where the latter utilizes crosshead deflection and assumes gauge lengths. This discussion […]

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The GMA Techline

April 1st, 2019

Vegetation causing gases under geomembrane? Q: I have a site where we are installing a high-density polyethylene (HDPE) liner in an existing pond. Because of some residual heavy metals in the top layer of soil, I would like to strip off the top 3–6 inches (7.6–15.2 cm) of soil and vegetation. Alternatively, we could mow and […]

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