Geotextiles

What is geotextile?

A geotextile is a permeable synthetic or natural fabric placed in or against soil. It separates two layers, lets water through while holding soil back, carries water in its own plane, cushions geomembranes against puncture and adds tensile strength to weak ground.

Ocean Geosynthetics supplies needle-punched non-woven geotextiles in polypropylene (PP) and polyester (PET), woven geotextiles, and natural coir and jute geotextiles. They go into roads, railways, airports, landfills, ponds, canals and slopes. Non-woven grades run from 90 to 1000 GSM, are made in ISO-certified facilities for domestic and export supply, and are available in continuous filament and staple fibre constructions. Roll widths and lengths are cut to the project requirement.

Each roll ships in a UV-resistant outer wrap. If the wrap stays on, rolls can be stored outdoors on site until they are laid.

How geotextiles work: the five functions

Geotextiles have been used in civil, coastal and environmental works for decades because one layer of fabric can replace a graded aggregate filter or a thicker granular layer. Designed and installed properly, that cuts aggregate quantities and the labour to place them. Most specifications describe the job in terms of five functions:

• Separation: keeps aggregate from punching into a soft subgrade and stops fines pumping up into the base. Under a road, this preserves the design thickness of the granular layers.
• Filtration: water passes across the fabric while soil particles are retained. This is how a geotextile replaces a sand filter around a French drain or under riprap.
• Drainage: thick non-wovens carry water within their plane, for example behind a wall or under a landfill cover. For large flows a drainage geocomposite is used instead. More on geotextiles in pavement and drainage.
• Protection: a heavy non-woven (typically 250 GSM and up) cushions an HDPE or LLDPE geomembrane against angular stones in the subgrade or the cover layer.
• Reinforcement and stabilisation: high-strength wovens add tensile capacity to embankments on soft ground and to walls. See retaining walls with geotextile and geogrid reinforcement.

Ocean geotextiles are used across transportation, ports and marine works, power, mines, heavy industry, river and flood protection, and landscaping.

Woven vs non-woven geotextiles

The two families do different jobs. Pick by the function the design needs, not by GSM alone.

	Woven	Non-woven (needle punched)
How it is made	Slit-film tapes, monofilaments or multifilament yarns woven on a loom	PP or PET fibres or filaments entangled by barbed needles
Tensile strength / elongation	High strength, low elongation	Lower strength, high elongation (conforms to uneven ground)
Permeability	Low for slit-film; high for monofilament	High across the plane, plus in-plane flow
Puncture and installation damage	Good tensile resistance, less cushioning	Better cushioning and resistance to installation damage
Main functions	Separation, reinforcement, stabilisation, filtration (monofilament)	Filtration, drainage, separation, geomembrane protection
Typical uses	Embankments on soft ground, haul roads, riprap underlay	Drain wraps, road separation, pond and landfill liner protection

Woven geotextiles

Woven geotextiles are made by weaving individual threads (monofilaments, fibrillated yarns or slit-film tapes) into one homogeneous sheet on a loom. The result carries high load at low strain, which suits road building over soft subgrades, embankments on soft ground, railway formations and aggregate separation.

Permeability depends on the yarn. Slit-film wovens have small, uneven openings and low flow rates, so they are a poor choice where the fabric must drain or filter fine soil. Monofilament wovens have regular, open apertures and are specified as filters under riprap and in coastal and river bank protection, where the fabric must pass water without clogging.

Used in: transportation, water resources, irrigation and flood control, ports and marine works. Properties: high tensile strength with low elongation, rot and biological resistance, chemically inert, UV stabilised.

Non-woven geotextiles

Non-woven geotextiles are made by bonding fibres rather than weaving them. Ocean’s range is needle punched: barbed needles drive through a web of fibres thousands of times until they interlock into a thick, felt-like fabric. Other makers use thermal or chemical bonding.

The thickness and random fibre structure give a non-woven high permeability, in-plane flow and good cushioning. That makes it the default where soil must be held back while water moves: wrapping French drains and subsurface drains, under riprap revetments where separation and drainage are both needed, and as a protection layer above and below geomembranes in ponds and landfills. Non-wovens stretch more than wovens, so they are not usually the first choice where the design calls for reinforcement.

Durability depends on cover, not on the woven/non-woven choice: any polymer geotextile left in sunlight degrades, while a buried one lasts the life of the structure. See how long non-woven geotextile lasts.

Used in: transportation, rail formation, ports and marine works, water resources and embankments, liner protection, residential plumbing and real estate, and waste management. Applications: asphalt overlays, erosion control, sediment dewatering bags, coastal protection, subsurface drainage, landscaping and landfills.

Geotextile types and trade names

Buyers and tenders use many names for the same few products. Here is what each one usually means.

PP geotextile

Polypropylene is light, resists acids and alkalis well and is the most common polymer for non-woven geotextiles. At the same GSM, Ocean’s PP non-wovens give higher tensile and puncture strength than its PET grades (see the specification tables). PP suits lime- or cement-treated soils and other high-pH conditions.

Polyester geotextile

Polyester (PET) melts at around 250 °C against about 165 °C for PP, so it is chosen where the fabric meets heat, for example under hot-laid asphalt. PET also has lower creep than PP, which matters for long-term reinforcement. It can lose strength by hydrolysis in strongly alkaline ground, so check soil pH and any lime or cement treatment before specifying it.

Needle punched geotextile

This is the manufacturing process behind Ocean’s non-woven range, in staple fibre or continuous filament. Needle-punched grades are used for slope works, filtration and geomembrane protection in landfills.

Monofilament geotextile

A woven geotextile made from single round filaments. The open, regular weave gives high water flow and resists clogging, so it is used as a filter in drainage systems, coastal protection and landfill works.

Drainage geotextile

Usually a non-woven chosen for permittivity and filtration: it wraps the aggregate or pipe in road edge drains, embankment drains and sports-field drainage so that soil does not migrate into the drain and clog it.

Paving fabric

A light non-woven laid on a bitumen tack coat between an old surface and a new asphalt overlay. Once saturated with bitumen it forms a moisture barrier and a stress-relieving interlayer that slows reflective cracking. It is used in road repair and new construction.

Silt fabric

Geotextile used in silt fences and sediment barriers on construction sites, agricultural land and shorelines. Water passes through while fine particles are trapped behind the fence.

Groundcover fabric

A light fabric for landscaping, nurseries, farms and horticulture. It suppresses weeds while air, water and nutrients still reach the soil.

Geosynthetic fabric

A general term for geotextiles. Geosynthetics is the wider family that also includes geomembranes, geogrids, geonets, geocells and geocomposites.

Key properties and test methods

Ocean’s data sheets report these properties to ASTM methods. Tender specifications (MoRTH Section 700, IRC:SP:59 and project-specific specs) set minimum values for the same properties, so compare like with like.

Property	Test method	What it tells you
Mass per unit area (GSM)	ASTM D5261	Weight of fabric per m². A grade label, not a performance value on its own.
Thickness at 2 kPa	ASTM D5199	Cushioning and in-plane flow capacity.
Wide-width tensile strength	ASTM D4595	Strength per metre width (kN/m), used for design.
Grab tensile strength	ASTM D4632	Index strength often quoted in survivability specs.
CBR puncture strength	ASTM D6241	Resistance to a 50 mm plunger; the main check for protection layers.
Apparent opening size (AOS)	ASTM D4751	Largest effective pore size; compared with the soil’s grain size for retention.
Permittivity and flow rate	ASTM D4491	Water flow across the fabric, so the filter does not hold back water.
UV resistance	ASTM D4355	Strength retained after exposure; Ocean non-wovens retain 70% after 500 hours.

Which geotextile GSM do you need?

The right grade depends on the job the geotextile has to do, the load on it and the material it sits against. The ranges below are typical starting points based on projects we have supplied. Final selection should follow the project design (subgrade strength, aggregate size, traffic and hydraulic requirements).

A few rules sit behind those ranges:

• Survivability first. The fabric must survive installation. Coarse, angular aggregate, heavy equipment and a soft subgrade all push the grade up, even for a simple separation job.
• Retention. The AOS must be small enough to hold back the soil it filters. Fine silts need a smaller AOS than sands.
• Flow. The fabric’s permittivity must exceed that of the soil by a design margin so water is never held back behind the filter.
• Protection under a geomembrane. Select on CBR puncture strength and thickness. A higher head of water and larger or sharper stones in the subgrade both call for a heavier grade.

Not sure which grade fits? Share your drawings or BOQ and our team will recommend a grade.

Applications in Indian projects

• Roads and highways: separation layer between the granular sub-base or WMM and a weak subgrade, and filter wraps for subsurface drains. IRC:SP:59 (Guidelines for Use of Geosynthetics in Road Pavements and Associated Works) and MoRTH Section 700 cover design and material requirements.
• Railways: separation in the track formation to stop subgrade fines pumping into the blanket and ballast.
• Airports and hardstands: separation and stabilisation under runway, taxiway and apron pavements.
• Ponds, canals and reservoirs: cushion layer under HDPE pond liners and geomembranes.
• Landfills: protection above and below the geomembrane, filter over drainage layers, and separation in the cap.
• Coastal and river works: filter under riprap, revetments and geo bags.
• Slopes and embankments: erosion control, basal reinforcement on soft ground, and coir or jute for vegetated slopes.

Installation basics

• Check each roll label against the order (polymer, GSM, width, length) and keep rolls in their wrap, off the ground, until use.
• Clear the subgrade of stumps, sharp stones and debris. Unroll the fabric flat and loose, without wrinkles, in the direction of construction.
• Overlap adjacent rolls as the specification requires. Around 300–450 mm is common on firm subgrade; soft subgrades need wider overlaps or sewn seams.
• Pin or weight the edges against wind, and on slopes anchor the top in a trench.
• Do not drive tracked plant directly on the fabric. Tip aggregate onto already-covered fabric and push it forward.
• Cover promptly. Polymer geotextiles lose strength in sunlight, so limit exposure to what the specification allows.

Geotextile projects we have supplied

• Bangalore Airport runway upgrade: 63,602 sq m of 200 GSM non-woven geotextile
• Leh Airport: 200 GSM non-woven geotextile
• Powergrid substation, Koppal, Karnataka: 110,000 sq m of non-woven geotextile
• Road project, Reasi, Jammu & Kashmir: 6,000 sq m of 150 GSM geotextile
• Pond lining, Bhopal: 250 GSM geotextile
• Landfill, Srinagar: 1,800 sq m of 285 GSM for cushioning and filtration

Related products

• HDPE geomembranes: the impermeable liner a protection geotextile is laid with.
• Geogrids: for base reinforcement and reinforced soil walls.
• Geocomposites: geotextile bonded to a drainage core for high in-plane flow.
• Geosynthetic clay liners: bentonite between geotextiles, as a barrier layer.

Frequently asked questions

What is geotextile used for?

Geotextile is a permeable fabric placed in or on soil to separate layers, filter water while holding back soil particles, drain water within its plane, protect geomembranes from puncture and reinforce weak ground. Common uses are road and railway subgrades, drainage trenches, pond and landfill lining, retaining walls and erosion control. See uses of geotextile membrane.

What is the difference between woven and non-woven geotextile?

Woven geotextiles are made by weaving tapes or yarns. They have high tensile strength and low elongation, so they suit separation and reinforcement. Non-woven geotextiles are needle punched from fibres. They are thicker and more permeable, so they suit filtration, drainage and cushioning. See the comparison above.

Does water pass through geotextile fabric?

Yes. Non-woven geotextile lets water through while retaining soil. Our 200 GSM PP grade has a flow rate of 70 l/m²/s at 50 mm head (ASTM D-4491). Read more: does water go through geotextile fabric.

PP or PET geotextile: which should I choose?

At the same GSM, our PP non-woven grades give higher tensile and puncture strength (for example 12 kN/m and 2,100 N at 200 GSM, versus 6 kN/m and 1,100 N for PET). PP also handles alkaline ground better. PET is chosen where the fabric meets heat, such as asphalt overlays, or where the project specification calls for polyester. Compare both in the specification tables.

How long does geotextile last?

When covered by soil or aggregate soon after installation, synthetic geotextiles last for the design life of the structure. Exposed to sunlight they degrade, so they should be covered promptly. Natural coir and jute geotextiles are designed to biodegrade once vegetation has established. Read more: how long does non-woven geotextile last.

What is the difference between geotextile and geomembrane?

A geotextile is permeable and lets water through. A geomembrane is impermeable and stops water. They are often used together, with geotextile protecting the geomembrane from puncture in ponds and landfills.

How is geotextile priced?

Price depends on polymer (PP or PET), GSM, quantity, roll size and delivery location. Send us your requirement for a quote.