Durability of geosynthetics based on accelerated laboratory testing

The use of geosynthetic products has been steadily increasing in the construction of reinforced fills for retaining walls and as steepened slopes and for landfills in the containment of hazardous waste. An impediment to their full utilization has been a lack of methods to assess their durability in the environment that they may be placed. Therefore, to assess the durability of existing and improved geosynthetics, it becomes necessary to assess their durability within a very short time with respect to environment parameters to which they will likely be subjected. This requires the development of accelerated laboratory tests at high temperature, permitting prediction of the behaviour of the geosynthetics in actual use. A Basic Autoxidation Scheme (BAS) for polyolefins has been adapted to develop a kinetic model for evaluating the mechanical degradation of polyolefin geosynthetic products. The model provides a satisfactory method to analyze the experimental laboratory data and estimates of strength loss caused by thermooxidation as a function of time. For polyester based geosynthetics, which are subject to hydrolysis, analysis of experimental data indicates that molecular weight loss is a dominant mechanism leading to mechanical strength loss in acidic and neutral environments. Fiber surface erosion, as well as molecular weight degradation, are responsible for mechanical strength loss, when polyester based geosynthetics are immersed in alkaline media. An Arrhenius type kinetic model provides a satisfactory analysis model, and permits estimates of strength loss due to hydrolysis as a function of time.