Overview
EN ISO 10773:2011 (ISO 10773:2011) defines a laboratory method to measure the permeability of clay geosynthetic barriers to gases. The standard focuses on steady-state gas flow through bentonite-containing geosynthetic liners used to contain gases in long‑term applications. Tests are normally performed with nitrogen and are designed to characterise gas transport behaviour as a function of bentonite moisture content.
Key topics and technical requirements
- Purpose: Determine steady-state gas flow through clay geosynthetic barriers and derive a gas flow index (GFI).
- Test conditions:
- Normal (confining) stress: 20 kPa (±5 %) applied to the specimen.
- Differential gas pressure across the specimen: 15 kPa.
- Specimen moisture range for testing: 90 % to 130 % (final bentonite water content).
- Typical specimen set: three samples with final water contents near 100 %, 110 % and 120 %. GFI is defined as the gas flow at 110 % moisture under the 15 kPa differential.
- Apparatus and specimen:
- Test cell with two chambers and support/containment material (glass beads 1–2 mm), lateral sealing with bentonite paste; specimen flow cross‑section diameter ≥ 150 mm to accommodate needle-punched and stitched products.
- Loading device, inlet pressure regulator, gas flow meter capable of measuring 0.1 ml/min to 5 l/min.
- Displacement gauge to monitor thickness change under load until stabilization.
- Procedure highlights: Controlled pre-hydration (immersion in deionized water), loading under 20 kPa (typically for one week), assembly with glass beads and sealing, application of 15 kPa differential pressure, monitor outlet volumetric flow until steady-state, then recover and dry specimen to determine final water content.
- Output: Plot of log(gas flux) versus bentonite water content; selection of best-fit curve yields the GFI.
Applications
EN ISO 10773:2011 is used wherever assessment of gas containment performance of bentonite geosynthetic liners is required. Typical practical uses include:
- Verifying product performance for long-term gas barriers (e.g., landfill and waste containment liners).
- Quality control and specification compliance for clay geosynthetic barrier manufacturers.
- Comparative laboratory testing by independent testing laboratories and research institutions.
Who uses this standard
- Geosynthetics manufacturers and product development teams
- Independent testing laboratories and accredited QC facilities
- Geotechnical and environmental engineers specifying containment systems
- Regulatory bodies and clients requiring validated gas containment performance data
Related standards
- ISO 554 - Standard atmospheres for conditioning/testing
- ISO 9863‑1 / ISO 9863‑2 - Determination of thickness at specified pressures
- ISO 11465 - Gravimetric water content determination
- EN 14196 - Test methods for mass per unit area of clay geosynthetic barriers
Keywords: EN ISO 10773:2011, ISO 10773, clay geosynthetic barriers, permeability to gases, gas flow index (GFI), bentonite geosynthetic barrier testing, geosynthetics testing.