Failure mechanisms of bentonite-polymer geosynthetic clay liner and geomembrane composite systems

A linear system contains geosynthetic clay liners (GCLs), consisting of a layer of sodium bentonite (Na-B) sandwiched by two layers of geotextiles are used as a barrier system for a variety of environmental containment applications. Polymer blended with bentonite was introduced into GCL named bentonite-polymer GCL (BP-GCL) to improve the chemical compatibility of GCL. The GMB/GCL liner systems are exposed to normal stress because of upper-covered waste, and thus the stability of the linear system is a concert. Normal stress applied on the GMB leads to the GMB/GCL system shear resistance, and failure occurred at the lowest shear resistance interface (e.g., GMB/GCL interface, GCL internal)

Hydration solution, bentonite, and polymer hydrogel existed in the GMB/GCL interface resulting in a substantial decrease in the shear resistance. The polymer migrated into GMB/GCL interface decreases interlock and friction between GMB/GCL interface.

The large direct shear tests were performed to investigate BP-GCL/GMB shear behavior. the effect of polymer elution and bentonite extrusion on GMB/GCL interface shear behavior was also investigated in this research.