Geotextile standards: tensile strength, sampling and acceptance testing

A spec is only as good as its test methods

Numbers on a geotextile spec — tensile strength, elongation, CBR puncture, permittivity — only compare if everyone measures them the same way. Tie each to its ASTM test method and the supplier, contractor and inspector are finally talking about the same fabric. The governing geotextile ASTM test methods are ASTM D4595 (wide-width tensile), ASTM D4632 (grab tensile), ASTM D4833 (puncture), ASTM D6241 (CBR puncture), ASTM D4491 (permittivity) and ASTM D4751 (AOS); GRI test-method guidance and the relevant ISO/IS codes sit alongside them.

Tensile strength

Tensile strength — kN/m for woven fabric, a class plus a wide-width or grab value for non-woven — is the headline number for separation and reinforcement. The standard fixes the method (wide-width D4595 vs grab D4632) and the elongation reported with it. A bare kN/m value with no method behind it is not a specification, it's a marketing figure; D4595 and D4632 give materially different numbers on the same fabric.

Sampling

Sampling rules set how many rolls a lot represents and how specimens are cut, so the tested pieces fairly stand for the whole delivery. This is the step people skip and then wonder why a passing certificate doesn't match the rolls on site. Follow the sampling standard and an acceptance test on a handful of specimens legitimately speaks for the consignment; skip it and a pass or a fail proves nothing about the lot.

Acceptance testing

Acceptance pits lab results from the sampled specimens against the specified class. The delivered fabric has to meet or exceed the spec on every governing property — not the average, every one. Mill test certificates support the result; independent re-testing confirms it on jobs where a liner failure is expensive. Keep certificates and reports in the project file for final acceptance.

Get certified geotextile

We supply woven and non-woven geotextile with test reports to the ASTM/GRI/ISO methods your spec names. Send the required class and we will quote a compliant grade with the documentation.