Direct shear testing on BENTOMAT has been performed by CETCO and other laboratories on a project-specific basis for the past several years. This data will give the designer some general information about the shear strength of commonly used GCL interfaces and should be the first step in evaluating a proposed liner system where slope stability is a concern.
The variables in any direct shear test are numerous, including specimen preparation, hydration pressures, liquids and sequencing, rate of shear, and others. Test results will vary accordingly, which is partially accountable for the wide range of data reported, even for similar interfaces.
Project-specific interface testing is emphatically recommended by CETCO. Individual test reports for most of the summarised data can be provided upon request.