Standards for Polypropylene Multifilament Woven Geotextiles (Filter Fabric)
The geotextile filter layer is evaluated under key standards to ensure performance in filtration and separation, particularly in tidal conditions:
- IS:1969: Specifies testing methods for woven fabrics, including tensile strength and elongation, ensuring compliance for filtration applications.
- ASTM D4751: Determines apparent opening size (AOS, O95 ≤ 75 microns), ensuring soil retention in filtration applications.
- ASTM D4491: Measures water permeability (≥ 9.0 L/m²/s), ensuring adequate water flow through the geotextile.
- ASTM D4632: Assesses grab tensile strength (e.g., 315 lbs or ~1.4 kN) and elongation (typically < 50% for woven geotextiles), ensuring durability.
- ASTM D4355: Tests UV stability, requiring ≥ 75% tensile strength retention after 500 hours of Xenon exposure, critical for tidal installations.
- EN ISO 10319:2015: Measures tensile strength (e.g., 50 kN/m) and elongation, using a 200 mm wide strip at controlled conditions (20°C ± 2°C, 65% ± 5% humidity).
- IRC:SP:59-2002 & MORTH Section 700: Specifies geotextiles for road construction, including filtration and separation in coastal and tidal environments.
Manufactured from UV-stabilized polypropylene multifilament yarns, the geotextile is resistant to chemicals (pH 3–12), bacteria, and UV degradation, ensuring durability in tidal conditions. The woven structure provides high tensile strength and controlled pore sizes (O95 ≤ 75 microns), ideal for filtration in high-energy water environments like coastal zones. Installation involves careful placement on excavated surfaces, with overlaps of 300 mm above water and 900 mm below water, stitched or spot-welded as per Engineer-in-Charge directives to prevent soil migration.[](https://www.gabionbasket.org/gabions/gabion-works-reinforcing-materials/geotextile-fabric.html)
Detailed Specifications
| Pore Size (O95, mm) | Permeability (L/m²/s) | Tensile Strength (kN/m) | Mass per Unit Area (g/m²) | Elongation at Break (%) | UV Stability | Material | Applications | Installation Requirements | Test Standards |
|---|---|---|---|---|---|---|---|---|---|
| ≤ 0.075 | ≥ 9.0 | 50 | 200 | 15–25 | ≥ 75% after 500 hr | PP Multifilament Woven | Coastal protection, tidal filtration | 300 mm overlap (above water), 900 mm (below water), stitching | IS:1969, ASTM D4751, D4491, D4632, D4355 |
Polypropylene multifilament woven geotextiles provide a robust filtration layer for tidal and coastal applications, ensuring soil retention, high water flow, and long-term durability under challenging environmental conditions.
Standards and Compliance
The geotextile complies with the following standards, informed by search results and industry practices:
- IS:1969: Indian standard for testing woven fabrics, covering tensile strength and elongation, ensuring suitability for filtration.
- ASTM D4751: Measures apparent opening size (AOS, O95 ≤ 75 microns), ensuring soil retention in tidal conditions.
- ASTM D4491: Confirms permeability (≥ 9.0 L/m²/s), ensuring water flow through the geotextile exceeds soil permeability (e.g., 10⁻⁴ to 10⁻⁸ m/s for sands to clays).
- ASTM D4632: Assesses grab tensile strength (e.g., 315 lbs or ~1.4 kN) and elongation (< 50% for woven geotextiles), ensuring durability.
- ASTM D4355: Tests UV stability, requiring ≥ 75% tensile strength retention after 500 hours of Xenon exposure, critical for tidal zones.
- EN ISO 10319:2015: Measures tensile strength (e.g., 50 kN/m) and elongation (15–25%) using a 200 mm wide strip, ensuring load-bearing capacity.
- IRC:SP:59-2002 & MORTH Section 700: Specifies geotextiles for road and coastal applications, including filtration in tidal environments.
Table Notes
- Specifications:
- Pore Size (O95): ≤ 0.075 mm (75 microns), per ASTM D4751, to retain fine soil particles (e.g., silts) in tidal conditions.
- Permeability: ≥ 9.0 L/m²/s, per ASTM D4491, ensuring water flow exceeds soil permeability (e.g., 100 L/m²/s typical for nonwovens, adjusted for woven).
- Tensile Strength: 50 kN/m, within the range for multifilament woven geotextiles (15–125 kN/m,), suitable for filtration and separation.
- Mass per Unit Area: 200 g/m², within the typical range (135–1000 g/m²,), balancing strength and permeability.
- Elongation at Break: 15–25%, typical for woven geotextiles, per ASTM D4632.
- UV Stability: ≥ 75% strength retention after 500 hours, per ASTM D4355, critical for tidal exposure.
- Material: Polypropylene multifilament woven, UV-stabilized, resistant to pH 3–12 and biodegradation.
- Applications: Coastal protection, tidal filtration, riprap underlayment, ensuring soil retention and water flow.
- Installation Requirements: Minimum overlap of 300 mm above water and 900 mm below water, with stitching or spot-welding to prevent soil migration, as directed by the Engineer-in-Charge.
- Test Standards: IS:1969, ASTM D4751, D4491, D4632, D4355, and EN ISO 10319:2015 for compliance.
- Tidal Conditions: The geotextile is designed for high-energy water flows and reversible flows in tidal zones, with UV stabilization and chemical resistance to prevent degradation. Specialist advice may be needed for highly alkaline groundwater or high suspended solids.
Additional Notes
Clogging Resistance: The small pore size (≤ 75 microns) minimizes piping, but tidal conditions with high suspended solids (e.g., turbid water) require monitoring to prevent clogging.
Multifilament Woven Structure: Provides high tensile strength and controlled pore sizes (O95 ≤ 75 microns), ideal for filtration in tidal conditions where fine soil retention is critical.
Installation: The geotextile is placed on cleared, excavated surfaces to avoid tearing, with overlaps (300 mm above water, 900 mm below) stitched or spot-welded to ensure continuity and prevent soil migration.
Permeability: The specified 9.0 L/m²/s is lower than typical nonwoven geotextiles (e.g., 100 L/m²/s,) but suitable for woven geotextiles in filtration, exceeding soil permeability (10⁻⁴ to 10⁻⁸ m/s).