Ageing HDPE geomembranes exposed to different climate conditions for 12 years

Abstract

High density polyethylene (HDPE) geomembranes are used in many geotechmical engineermg applications, remaining sometimes exposed to climatological conditions for a long time. They are expected to experience degradation due to that exposure, leading to a decrease in their engineering properties. To study the degradation m the properties of field exposed geomembranses, a research program has been in progress at Laboratório Nacional de Engenharia Civil, since 1999. This paper addresses the degradation in the properties of HDPE geomembranes, installed at eight different locations, alter 12 vears of exposure. Another goal of this work 15 to compare the properties of exposed geomembranes with the minimum requirements currently recommended by the Geosynthetic Research Institute (GRD, in order to verify that they still meet those requirements. Samples were exhumed from different sites located ali over Portugal and the properties of the geomembranes were tested m laboratory. The properties studied were: density, melt flow index, tensile properties, carbon black content, and oxidative induction time. The results have shown that the properties of the peomembranes exposed to climatic conditions presented some degradation, especially in the oxidative induction time and density. Also, they have indicated that the exposed geomembranes for 12 vears even met the minimum requirements established by GRI-GMI3, except for the oxidative induction time.