Geosynthetic clay liners (GCL’s) are composite products consisting of a thin layer of high purity clay (powdered or granular) sandwiched between two layers of geotextile.  GCL’s are primarily used in composite liner systems in conjunction with Geomembranes to provide highly effective containment solutions. GCL’s have replaced compacted clay liners in most modern waste containment facilities the combination of synthetic and natural materials requires specialized test methods and apparatus.