ASTM D4595 -  Standard Test Method for Tensile Properties of Geotextiles by the Wide-Width Strip Method

Theory:

ASTM D4595 is a dependable method for specifying geotextiles in tension because it accurately replicates real world scenarios. The larger strip is much wider than the sample used in standard textile strip tests such as D5035. 

 

Geotextiles are typically used to reinforce embankments to prevent catastrophic occurances such as mudslides during rainstorms. During an event such as a storm, soils will expand once they absorb water. These soils will begin to break apart at only 1-2% strain, therefore most geotextiles are designed to expand slightly without compromising the integrity of the entire woven fabric. 

Geometry:

The specimen for this test is 8x8 and the procedure necessitates that the entire textile strip be secured within the grips. 

Solution:

Extra wide grip faces are required for this test. The standard specification requires the whole 8x8 strip to be fixtured within the workholding jig. A set of 8x3 grip faces are shown in the video which are used in conjunction with a hydraulic grip setup. 

Analysis:

Sample calculations for ASTM D4595 are typically specified by the percent strain and pulled at 25mm/min. Strain is another term for elongation and standard delineations occur at 1, 2, 5, and 10%. Most fabrics have a bit of slack within the weaving and therefore do not experience full tensile stress until about 5% total elongation.