Interface Shear‐Strength Properties of Roughened HDPE

It is generally perceived that roughened high‐density polyethylene (HDPE) has superior interface frictional properties, when in contact with any type of granular material, compared to smooth HDPE. Large‐scale direct shear interface test results are presented that indicate that this is not always the case and that the shear strength of finer‐grained materials may be better mobilized by the currently available roughened HDPE than by coarser‐grained materials. Based upon a limited number of tests, there appears to be a direct relation between soil composition, depth of texturing, and the amount of shear strength mobilized during shearing. This study indicates that the ratio of D80 of the granular material to the height of texturing (h_text) of the roughened HDPE may be used to determine how much of a materials shear strength may be mobilized at the interface. The results of this testing suggest the importance of testing all interfaces when performing analysis and design for geosynthetic liners and covers.