Polyethylene geomembranes have historically been manufactured using carbon black in their formulation to improve their resistance to ageing due to UV radiation. The black color, on the other hand, absorbs most of the solar energy reaching the surface. The temperature rise induced in the geomembrane is the source of numerous problems in the field, including the formation of wrinkles, thermo-oxidative degradation of the polymer, and desiccation of the soil located underneath. In order to minimize this issue, a fine white layer can be added on the exposed surface of the geomembrane using titanium dioxide pigments for instance in the formulation. It is intended to reflect the solar radiation and therefore, reduce the geomembrane temperature. This paper presents the results of a study aimed at quantifying the difference in heat generation under solar irradiation associated with the presence of the white surface layer. The temperature of black only and white/black geomembrane specimens was measured while they wereexposed to various laboratorycontrolled solar irradiances using a Xenon-arc chamber modified for the purpose of this project.The coefficient of thermal expansion of these geomembranes was also determined by thermomechanical analysis. Temperature was found to be significantly lower in the white-surfaced geomembranes, compared to the black ones, with differences in the range of 25°C. The thermal expansion wasreduced by up to 55- 60%. Theseresultswere combined with climatic data for Toronto, Canada, to quantify the effect of the white layer on the geomembrane thermal expansion.The calculated thermal expansionisused to estimate the effect of the white layer on the generation of wrinkles caused by solar radiation, and conditions for installation and service operations of exposed geomembranes.
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