Overview
ISO 13431:1999 - "Geotextiles and geotextile-related products - Determination of tensile creep and creep rupture behaviour" defines a laboratory method to assess long‑term tensile creep and creep‑rupture performance of geotextiles and related products in an unconfined situation. Published in 1999 (first edition), the standard is intended for cases where long‑term strain/time behaviour or premature rupture of the reinforcement could cause structural collapse. Because tests run over long durations and are complex, ISO 13431 is not recommended as routine quality control.
Key topics and technical requirements
- Scope and purpose: measures time‑dependent tensile strain (creep) and time to tensile creep rupture under constant static loads.
- Specimen preparation and sampling: sampling and specimen cutting follow EN 963; specimen counts are specified (four specimens for creep behaviour, twelve for creep rupture).
- Specimen dimensions: minimum gauge length ≥ 200 mm (special provisions for geogrids and mesh/rib structures); widths depend on lateral contraction and product type; use of a technically representative width (TRW) is defined.
- Conditioning: specimens conditioned in a standard atmosphere per ISO 554 until mass stabilizes; testing under the same conditions is required.
- Loading and preload: a preload equals 1% of tensile strength (with limits); tensile creep loads are applied as percentages of measured tensile strength (examples in the standard include 5%–60%).
- Measurement and timing:
- Strain measured continuously or at prescribed intervals (detailed early‑time and long‑term intervals up to ~1 000 h; 42 days = 1 008 h).
- Time recording for creep rupture requires accuracy of ±1%.
- Apparatus requirements:
- Slip‑free grips, eccentricity prevention (universal joint/spherical seating).
- Stiff, vibration‑isolated loading frame.
- Loading system maintaining load within ±1% (dead weights, levers, hydraulic/pneumatic allowed if calibrated).
- Strain measuring system with ±0.1% gauge length accuracy.
- Reference tests: wide‑width tensile characteristics are determined by EN ISO 10319 prior to creep testing.
Practical applications
ISO 13431 is used to:
- Evaluate long‑term performance of geotextiles and geogrids for reinforced soil and retaining structures.
- Support design decisions where time‑dependent deformation or rupture risk is critical.
- Provide test data for product development, research, certification, and contract specifications.
- Compare materials for durability under sustained loads (creep resistance).
Who uses this standard
- Geotechnical and civil engineers specifying reinforcement materials.
- Geosynthetics manufacturers conducting product R&D and type testing.
- Independent testing laboratories performing long‑term performance tests.
- Standards committees and procurement/specification writers.
Related standards
- EN 963 - Sampling and preparation of test specimens (geotextiles)
- EN ISO 10319 - Wide‑width tensile test for geotextiles
- ISO 554 - Standard atmospheres for conditioning and/or testing
Keywords: ISO 13431, tensile creep, creep rupture, geotextiles, geogrids, long‑term testing, tensile strength, TRW, geosynthetics testing.
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