Geotextile Membranes Explained

Geotextile membranes are the name given to large sheets of fabric that are used in ground engineering and drainage applications, such as ground filtration, soil separation, ground reinforcement and soakaways and land drains. They are often referred to as Terram - which is actually a brand name - in much the same way the vacuum cleaners are often called Hoovers. There are two main types of geotextile, woven and non-woven, and they have different qualities and therefore different uses. At Drainage Sales we stock both types.

Woven Geotextiles

As the name suggests, woven geotextiles are made by weaving individual threads or tapes of material on a loom to create a large sheet. The advantages of woven over non-woven is that the membrane itself is stronger overall, slightly stiffer and a little cheaper.

Because of the additional strength, woven geotextiles have a higher load rating. As a result they are generally used in road, embankment and railway construction to reinforce and stabilise the structural layers, keeping each layer apart and maintaining the integrity of the structure. Without such a membrane, load stresses over time would force the granular stone layers into the softer soil, which would cause the road or other structure to rut and perhaps even drop in places.  Whilst all geotextiles are permeable (they allow water through), the woven type does not filter water as well as the non-woven version.

Non-Woven Geotextiles

This type of geotextile is made by needle-punching or heat-bonding synthetic fibres together to create a single sheet. They are not as stiff as their woven counterparts, so whilst the uses are similar they are generally used when a lesser load capacity is required. The main quality of non-woven geotextiles is their excellent filtration capability – because of this they are most often used in a drainage capacity. Non-woven geotextiles are excellent at allowing water to pass through whilst keeping fine particles of soil out, so the most common use is the wrapping and protection of soakaway crates and land drains. Non-wovens are also used beneath domestic patio and block paving bases, keeping the granular layer apart from the soil whilst still allowing the water to drain away freely.

Sizes

Both types of geotextile are generally supplied in rolls of 4.5m wide by 100m long. For those working on smaller projects both types are also available to buy by the metre from Drainage Sales.

Commercial Applications

For larger commercial applications where the strength of the membrane is key, different grades are available. Please contact us if you require details on a commercial grade geotextile membrane.