scope:

This document describes an index test method to determine the friction characteristics of geotextiles and geotextile-related products in contact with a standard sand, i.e. with a specified density and moisture content, under a normal stress and at a constant rate of displacement, using a direct shear apparatus The same testing procedure can be used with any type of soil with the density and moisture content that is required to evaluate the performance under specific conditions or with another geotextile and geotextile related product under a normal stress and at a constant rate of displacement, using a direct shear apparatus. The procedure can also be used for testing geosynthetic barriers. When geogrids are tested in contact with soil with a rigid support, the results are dependent on the friction with the support and the results are not necessarily realistic. The accuracy of the test should be verified by calibration tests.