COMPRESSION TESTING OF GEONETS AND DRAINAGE COMPOSITES

Currently, the American Society for Testing and Materials (ASTM) D 1621 is the most commonly used method to determine the compressive strength of geonets and geocomposites. Unfortunately, this loosely written standard is not a D 35 "geosynthetic" standard, but rather a D 20 "plastics" standard. As such, it is commonly modified to suit the needs of specifiers and those interested in conformance testing. Because of these inconsistencies, the ASTM D 35 committee has been in the process of casting a compressive strength standard of their own. Unfortunately, their attempts have been ongoing since the mid-1980s. This feature offers the following recommendations. The compression test for geonets and drainage geocomposites should be a quick index test. It is anticipated that the results of the test will be used to evaluate product uniformity. The loading platens used for the test should be rigid enough to resist bending, and they should be capable of applying a uniform stress. The upper loading platen should be attached to the normal stress assembly in such a manner that no stress is placed on the specimen until the commencement of the test. The size of the platens should be at least 56 sq mm (9 sq in).