ASTM D7748-12e1

This test method is considered satisfactory for manufacturing quality control testing of a specific geosynthetic; however, caution is advised since information about between-laboratory precision is incomplete. Comparative tests as directed in 5.1.1 may be advisable.

In case of a dispute arising from differences in reported test results when using this test method for acceptance testing of commercial shipments, the purchaser and the supplier should conduct comparative tests to determine if there is a statistical bias between their laboratories. Competent statistical assistance is recommended for the investigation of bias. As a minimum, the two parties should take a group of test specimens that are as homogeneous as possible and that are from a lot of material of the type in question. Test specimens should then be randomly assigned in equal numbers to each laboratory for testing. The average results from the two laboratories should be compared using the appropriate statistical analysis and an acceptable probability level chosen by the two parties before testing is begun. If a bias is found, either its cause must be found and corrected or the purchaser and the supplier must agree to interpret future test results with consideration to the known bias.

This test method is not suitable for very limp geosynthetics or those that show a marked tendency to curl or twist at a cut edge.

The stiffness of a geosynthetic may change with storage.

No evidence has been found showing that bending length is dependent on specimen width. The tendency for specimens to curl or twist will affect the result, because of the rigidity provided at the edge. Consequently, the edge effect is less of an issue for a wider strip.

1.1 This test method covers the measurement of stiffness properties of geogrids, geotextiles and geogrid-geotextile composites all of which are referred to as geosynthetics within this standard. Bending length is measured and flexural rigidity is calculated through use of the cantilever test procedure.

1.1.1 This test method employs the principle of cantilever bending of the geosynthetic under its own mass.

1.2 This test method applies to geogrids, geotextiles and geogrid-geotextile composites.

1.3 This test method is for manufacturing quality control purposes only, to ensure uniformity and consistency of flexural rigidity for a specific product from roll to roll and lot to lot.

1.4 The values stated in SI units are to be regarded as the standard. The U.S. customary units may be approximate.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.