Shear strength of reinforced geosynthetic clay liner

Direct shear tests are conducted to evaluate the internal strength of a reinforced geosynthetic clay liner (GCL) at normal stresses between 3.45 and 69.0 kPa. The polypropylene reinforcement increases the peak internal strength compared to that reported in the literature for unreinforced GCLs; however, the reinforced GCL exhibits a postpeak reduction in strength with displacement due to failure of the reinforcement. Direct shear tests are also conducted to evaluate the interface strength between the reinforced GCL and other geosynthetic materials. Extrusion of-bentonite from the GCL into the interfaces is noticed and may reduce the interface strengths. Peak interface strengths between the;. GCL and a smooth geomembrane or a drainage geocomposite are less than the internal strength at all normal-stresses tested. However, the peak interface strength between the GCL and a textured geomembrane is limited by the peak internal strength for normal stresses exceeding 13.8 kPa. Postpeak reductions in strength with displacement occur for this interface at these higher normal stresses due to reinforcement failure.