GeoTextile Grab Test
ASTM D4632 describes a test procedure for measuring the breaking load and elongation of geotextiles. The test is a "grab test" which means that the grip "grabs" the fabric in the middle of the specimen. This test is very similar to ASTM D5034 which is the grab test for normal textile samples. This test should only be used for woven fabrics and should not be used for knitted textile or non-woven materials.
The textile samples must be cut with precision and should measure 4x8". About 1% of all production material should be sampled and tested.
A benchtop tensile testing machine is used to pull the geotextile at a constant-rate-of-extension (CRE). The grips and grip jaw inserts are extremely important for conformity to this test method. The grip faces must measure 2 inches (50.4mm) in height and 1 inch (25.4mm) in width. A universal joint adapter can be used to align the axial tension, however this is not always necessary.
The ultimated tensile strength, also known as the breaking load is measured as the load peak seen during the test. The system can also measure elongation using either the crosshead position or the Galdabini MICRON balanced extensometer.