5.1 As explained in Test Method D4595, narrow geotextile specimens demonstrate the tendency to contract (neck down) in the gage area when under stress. The wider width specimen will minimize this phenomenon in seams during strength testing. The results achieved in this test method can more accurately correlate to the seam strength values anticipated in the field.

5.2 This test method can be used to measure the seam strength of geotextiles, and may also be used for acceptance testing of commercial shipments of geotextiles. When strength is not necessarily a design consideration of seam interaction, an alternate method for determining the seam strength, such as Test Method D1683, may be used depending on the specification requirements. Because current information about laboratory precision is incomplete, comparative tests, as described in 5.2.1, may be advisable.

5.2.1 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 perform 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 from the same lot of geotextile, that utilize a like method of seam assembly to achieve seam interaction. The specimens should then be randomly assigned in equal number to each laboratory for testing. If a bias is found, either its cause must be determined and corrected, or the purchaser and the supplier must agree to interpret future test results in light of the known bias.

5.3 Although other methods of determining seam strength are available, this test method, that measures wide specimens, will more accurately correlate to the anticipated performance in the field.

5.4 This test method can be used to help determine seam design engineering for the geotextiles being evaluated.