5.1 This test method is an index test to estimate and compare the in-plane hydraulic transmissivity of one or several candidate geosynthetics under specific gradient and stress conditions.

5.2 This test method may be used for acceptance testing of commercial shipments of geosynthetics, but caution is advised since information about between-laboratory precision is incomplete. Comparative tests as directed in 5.2.1 are advisable.

5.2.1 In case of a dispute arising from differences in reported test results when using this procedure for acceptance of commercial shipments, the purchaser and the supplier should first confirm that the tests have been conducted using comparable test parameters including specimen conditioning, normal stress, hydraulic system gradient, etc. Comparative tests then should be conducted 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 formed from a lot of the material in question. The test specimens should be assigned randomly to each laboratory for testing. The average results from the two laboratories should be compared using the Student's t-test for unpaired data and an acceptable probability level chosen by the two parties before testing is begun. If bias is found, either its cause must be found and corrected or the purchaser and supplier must agree to interpret future test results in light of the known bias.

1.1 This test method covers the procedure for determining the in-plane transmissivity of geosynthetics under varying normal compressive stresses using a radial flow apparatus. The test is intended to be an index test used primarily for geotextiles, although other products composed of geotextiles and geotextile-type materials may be suitable for testing with this test method.

1.2 This test method is based on the assumption that the transmissivity of the geosynthetic is independent of orientation of the flow and is, therefore, limited to geosynthetics that have similar transmissivity in all directions and should not be used for materials with oriented flow behavior.

1.3 This test method has been developed specifically for geosynthetics that have transmissivity values on the order of or less than 2 × 10⁻⁴ m²/s. Consider using Test Method D4716/D4716M for geosynthetics with transmissivity values higher than 2 × 10⁻⁴ m²/s.

1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.

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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.