As a new class of polymer-modified geosynthetic clay liners (GCL) that will be added to CETCO’s existing RESISTEX GCL family, the RESISTEX Universal GCL series performs well against calcium chloride (CaCl2). CETCO can now offer customers a comprehensive portfolio of solutions to address a wide spectrum of leachates.
Designed to withstand medium- to high-strength leachates, including coal ash, high-pH mining leachates and low-pH mining leachates, the series includes RESISTEX U40 GCL, RESISTEX U60 GCL and RESISTEX U80 GCL. Each product variation is distinguished by its polymer content.
By reducing the effects of ion exchange and offering lower hydraulic conductivity against aggressive groundwater chemistries, the RESISTEX Universal GCL series is an important addition to the existing product line with its proven performance against aggressive leachates. This includes increased swelling and sealing capabilities, and robust chemical resistance to aggressive leachates at higher effective stresses post-ion exchange.
To validate the performance power of the RESISTEX Universal GCL series against CaCl2, a team of CETCO researchers investigated the influence of polymer loading on hydraulic conductivity before and after ion exchange to determine the optimal polymer content. The study was intended to examine the performance limits of several new polymer-modified GCLs (PMGs). The results showed that the mass per unit area of the PMGs can be reduced by 50% while maintaining better hydraulic performance than traditional bentonite-based GCLs. For aggressive leachate chemistries, in applications such as evaporation ponds and pregnant heap leach solutions, the products can be tailored to deliver low hydraulic conductivity while still providing a cost-efficient alternative to compacted clay liners. In a separate experiment, the durability of the product against ion exchange in wet/dry cycling was also explored, as well as the impact of ion exchange on the swelling and sealing potential of the bentonite/polymer blends. Based on the identifying markers, a conclusive improvement in swelling and sealing was detected. The data demonstrates the RESISTEX Universal GCL series’ ability to provide low hydraulic conductivity against extreme leachates at higher effective stresses. These new materials provide design engineers with a cost-effective option to ensure low leakage to the environment.