Modifying ASTM E96 to assess water vapour transmission rates of geomembranes at high temperatures

This paper presents a novel methodology for assessing water vapour transmission rates (WVTRs) through geomembranes across a wide temperature range, from 20 °C to 90 °C. This expands upon the existing ASTM E96 standard, limited to temperatures up to 32 °C. The study focused on 1.5 mm thick high-density polyethylene (HDPE) and polyvinyl chloride-ethylene interpolymer alloy (PVC-EIA) geomembranes. The WVTR results—0.15 g/m²h at 25 °C for PVC-EIA and 0.02 g/m²h at 30 °C for HDPE—align closely with values reported in existing literature for similar geomembranes at lower temperatures, validating the methodology proposed in this study. Under elevated temperatures, the WVTR of PVC-EIA increased significantly to 4.7 g/m²h at 90 °C, while HDPE showed a slower increase, reaching only 0.4 g/m²h at the same temperature. This disparity is attributed to polymer composition and behaviour differences under high temperatures. This study's methodology provides a dependable approach for accurately measuring WVTR, including high temperatures relevant to various applications where such data is currently lacking.