Effect of elevated temperatures on the degradation behaviour of elastomeric bituminous geomembranes

Abstract

The effect of elevated temperatures on the degradation of an elastomeric bituminous geomembrane (BGM) when exposed to air and deionized (DI) water at temperatures between 22 and 85 °C is investigated using immersion tests. The changes in the mechanical, chemical and rheological properties of the BGM are examined over approximately two years under different ageing conditions. It is shown that the BGM exhibited different degradation rates in its different components when exposed to elevated temperatures that are dependent on the incubation media. In air, the BGM exhibited thermo-oxidative degradation in the elastomeric bituminous coat that changed the bitumen glass transition temperature and increased its rigidity. Further degradation led to the brittleness of the bitumen coat before any degradation in the tensile and puncture strengths of the BGM. In contrast, exposure to DI water resulted in faster degradation of the mechanical properties of the BGM, while the bitumen coat exhibited substantially less degradation than in air. Arrhenius modelling is used to estimate the degradation times of the BGM at a range of field temperatures for both media.