IS 13325:2020 Part 4 is the Indian Standard (BIS) for geosynthetics - geotextiles - methods of test for mechanical properties. This standard (Part 4) specifies a method for determining the trapezoidal tear strength of geotextiles. It outlines the test principle, apparatus, specimen preparation, procedure, and calculation for measuring the force required to propagate a tear in the material.
Specifies methods for determining mechanical properties of geotextiles such as tensile strength, puncture resistance, and tear strength.
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
geotextilesgeosyntheticswoven geotextilesnon-woven geotextiles
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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