IS 13325:2020 Part 3 is the Indian Standard (BIS) for geosynthetics - geotextiles - methods of test for hydraulic properties. This standard (Part 3) specifies laboratory methods for determining the water permeability of a single layer of geotextile normal to its plane, under no compressive load. It covers procedures for both the constant head method, suitable for materials with higher permeability, and the falling head method for materials with lower permeability.
Specifies methods for determining hydraulic properties of geotextiles such as permeability, permittivity and apparent opening size.
Overview
- Status
- Current
- Usage level
- Specialized
- Domain
- Geotechnical — Geosynthetics and Ground Improvement
- Type
- Testing Method
Also on InfraLens for IS 13325
Practical Notes
! Ensure the specimen is clamped perfectly along the non-parallel sides of the trapezoid to ensure force is applied correctly.
! The test result is an average of the five highest peaks from the force-elongation curve, not just the single maximum peak.
! This test is critical for applications where the geotextile might be subjected to puncture and subsequent tearing, such as under sharp aggregate.
Frequently referenced clauses
geosyntheticsgeotextilesnon-woven geotextilewoven geotextile
International Equivalents
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Key Values6
Quick Reference Values
Test specimen dimensions100 mm x 200 mm
Initial slit length15 mm
Rate of jaw separation (CRE)300 ± 10 mm/min
Pre-tension for specimens ≤ 200 g/m²1 N
Pre-tension for specimens > 200 g/m²2 N
Number of specimens per directionMinimum 5
Key Formulas
Tear Strength (N) = Average of the five highest peak forces recorded during the test for each specimen.
Tables & Referenced Sections
Key Clauses
Clause 3 - Principle
Clause 5 - Apparatus
Clause 6 - Preparation and Conditioning of Test Specimens
Clause 7 - Test Procedure
Clause 8 - Calculation and Expression of Results
Clause 9 - Test Report
Frequently Asked Questions4
What is the purpose of the trapezoidal tear test?+
To determine the force required to propagate a tear from a pre-cut slit in a geotextile specimen (Clause 3).
What is the specified speed for the tensile testing machine?+
The constant rate of extension (CRE) is 300 ± 10 mm/min (Clause 7.3).
How many specimens are tested?+
A minimum of five specimens in the machine direction and five in the cross-machine direction are required (Clause 6.1).
What are the dimensions of the test specimen?+
The specimen should be a rectangle of 100 mm width and 200 mm length (Clause 6.2).
QA/QC Inspection Templates
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