ISO 25619-1:2021

Overview

ISO 25619-1:2021 - Geosynthetics - Determination of compression behaviour - Part 1: Compressive creep properties specifies index test methods for measuring time‑dependent compression (compressive creep) of geosynthetic products. It defines specimen preparation, conditioning, test apparatus and procedures for two loading modes: normal compressive loading (standard method) and combined normal and shear loading (for shear‑sensitive, columnar or cuspated structures). Tests may be performed on dry specimens or on specimens immersed in water (required when any component contains a hydrophilic polymer).

Key topics and technical requirements

• Scope & purpose: Index methods to quantify compressive creep strain, initial and compressed thickness, and detect compressive creep collapse.
• Specimen requirements:
  • Square specimens, minimum 100 mm × 100 mm; orientation in machine direction (MD) and cross‑machine direction (CMD) must be indicated.
  • For structured cores, plates must cover at least three contact points/lines as specified.
• Conditioning:
  • Standard atmosphere: (20 ± 2) °C and (65 ± 5) % RH (ISO 554).
  • If immersed testing is required, soak 24 h in deionized water (ISO 3696) at (20 ± 2) °C; water depth above specimen ≤ 25 mm.
• Loading methods:
  • Normal compressive load (standard): vertical load applied and thickness recorded over time - typical test duration 1 000 h (or agreed alternative).
  • Combined normal + shear: used for products sensitive to shear failure.
• Apparatus & measurements:
  • Compression rig with parallel metal plates and vertical travel exceeding specimen thickness; maintain applied stress within ±1 % accuracy.
  • Thickness measurement accuracy 0.02 mm, mean of at least three points unless central measurement is used.
  • Loading systems must apply the full stress without impact; dead‑weight setups require balanced support during assembly.
• Definitions: initial thickness (measured at 2 kPa), initial compressed thickness (measured 1 min after normal loading or 4 min after combined loading), compressive creep strain, and compressive creep collapse.

Applications and users

ISO 25619-1 is used to assess long‑term compressive performance of geosynthetics in applications such as:

• landfill liners and drainage cores
• geosynthetic cushions and protective layers
• geocellular cores and structured core products Primary users:
• Geotechnical and civil engineers specifying materials
• Geosynthetic manufacturers performing quality control and product characterization
• Test laboratories conducting standardized compressive creep testing
• Procurement/specification teams requiring validated performance data

Related standards

• ISO 9862 (sampling and specimen preparation)
• ISO 9863‑1 (thickness measurement at specified pressures)
• ISO 10318‑1 (geosynthetics terminology)
• ISO 3696 (water for laboratory use)
• ISO 554 (standard atmospheres for testing)

Keywords: ISO 25619-1, geosynthetics, compressive creep, compression behaviour, test method, compressive creep properties, compression testing, hydrophilic polymer, specimen conditioning.