Standard Practice for Determination of the Radial Tensile Properties of Geogrids Under Low Radial Strain

Importancia y uso:

4.1 The determination of the tensile force-elongation values of geogrids provides index property values. This standard practice shall be used for the determination of radial properties, judgment of conformity of product manufactured, and acceptance of commercial shipments of geogrids.

4.2 The standard strain at which this practice is applied is 2 %, as this has been established and accepted over the years as the lowest strain at which consistent measurement of the properties of geogrids can be achieved. However, if a customer or specifier requires calculation at a lower strain, this can be done provided the higher standard deviation this can give is accepted.

4.3 In cases of dispute arising from differences in reported results when using this standard practice for acceptance testing of commercial shipments, the purchaser and supplier should conduct comparative tests and calculations 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 which are as homogeneous as possible and which are from a lot of material of the type in question. The 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 Student's t-test for unpaired data and an acceptable probability level chosen by the two parties before the testing began. If a bias is found, either its cause must be found and corrected or the purchaser and supplier must agree to interpret future results in light of the known bias.

4.4 This standard practice is applicable to all geogrids with two or three sets of ribs in which variation of tensile properties between different sets of parallel ribs is 20 % or less. For multiple-layered geogrids, it should be applied to each layer individually and the results for all layers summed in each radial direction.

Subcomité:

D35.01

Volúmen:

04.13

Número ICS:

59.080.70 (Geotextiles)

Palabras clave:

geogrid; geogrid rib; index test; radial load; radial stiffness; radial strain;