What are the types of Geocomposites?

A geocomposite is a factory-made product that combines two or more geosynthetics: geotextiles, geogrids, geonets and/or geomembranes. Any of these four can also be combined with another material, such as a formed plastic sheet, steel cables or soil. The aim is one product that does a job better, or more cheaply, than its parts laid separately.

The most common kind is the drainage geocomposite, which replaces a layer of granular drainage fill. It usually has two components: a three-dimensional polymer core that carries the water, and a geotextile filter that lets water into the core while keeping the surrounding soil from washing in and clogging it. Across all types, geocomposites perform five functions: separation, reinforcement, filtration, drainage and containment.

Types of Geocomposites:

Fiber Glass Geo Composite

Fibreglass geogrid composites come in two forms: fibreglass yarn warp-knitted onto a non-woven geotextile, or a fibreglass geogrid bonded to a non-woven geotextile. The geotextile handles filtration and separation and the fibreglass adds stiffness and strength. Their main use is in asphalt overlays, where the composite is laid between the old and new layers to slow reflective cracking.

Geotextile – Geonets Composites

A geotextile on one or both sides of a geonet, or a geotextile-geonet-geotextile sandwich, still separates and filters, but it drains far more water in-plane than a geotextile alone. Laid horizontally, these composites intercept water rising through the capillary zone where frost heave or salt migration is a problem: the water enters the composite and flows sideways through the geonet, away from where it would cause damage.

They are also used to collect and carry leachate in landfills, and to vent gas or drain water from beneath pond liners. See how a geocomposite drainage layer works.

Geotextile – Geomembrane Composites

Geotextiles are laminated to one or both sides of a geomembrane for several reasons. The geotextile raises the geomembrane’s resistance to puncture and tear, increases friction against sliding on slopes, and adds tensile strength of its own. When the geotextile is a heavy needle-punched non-woven, its in-plane flow capacity (transmissivity) also lets it carry water or leachate along the face of the geomembrane.

Geomembrane – Geogrids Composites

Some geomembranes and geogrids are made from the same polymer, high-density polyethylene, so the two can be welded together into an impermeable barrier with extra strength and better friction.

Geotextile – Geogrid Composites

A geotextile with low modulus, low strength or high elongation at break can be improved a great deal by combining it with a geogrid or a woven scrim. The geogrid carries the load and the geotextile separates and filters.

Geotextile / Polymer – Core Composites

Here the core is a semi-rigid plastic sheet, extruded or formed into a shape with open channels so that large volumes of water can flow through it. A geotextile filter wraps one or both faces. Many such systems exist. Strip or wick drains (prefabricated vertical drains) belong to this group, and some writers have proposed the term “geospacer” for these cores.

A wick drain core is usually fluted and about 4 in. (100 mm) wide, with a geotextile filter around it. Installed in a grid, wick drains speed up consolidation of soft, saturated fine-grained soils, and they have largely replaced traditional sand drains for this job.

GEOSYNTHETIC – SOIL COMPOSITES

Geosynthetic clay liners are one example of a geosynthetic-soil composite, and there are others. Geocells are strips of polymer or geotextile joined into a honeycomb that is stretched open on site and filled with soil. The cells confine the fill, and together they form a stiff mattress. Large earth embankments have been built on geocell mattresses over weak soils, and the mattress can serve as a low-cost mat foundation.

Drainage Geocomposites

Prefabricated edge drains also fall under drainage geocomposites. These panels, usually about 18 in. (45 cm) high, are installed in a trench along the edge of a highway pavement or railway track to drain water sideways out of the pavement layers. They install quickly and cost less than a conventional granular trench drain.

Applications Of Geocomposites

In roads, geocomposites provide separation, drainage, filtration and reinforcement, and improve the strength and durability of the soil under the pavement.

Geonet geocomposites, a geonet with geotextile bonded to one or both sides, drain the base of embankments and the backfill behind retaining walls and bridge abutments. Their in-plane drainage capacity is much higher than their cross-plane capacity, which is what makes them good drainage elements.

As the Basal layer (Horizontal Direction)

On embankments over soft soil, or where the water table is high, good practice is to place a sand layer at the base of the embankment, between the subsoil and the fill. This layer separates the fill from the fine-grained subsoil so it is not fouled, drains off excess pore water pressure so the embankment is more stable, and spreads the load evenly over the subsoil. A drainage geocomposite can do the same job in place of the sand blanket.

As Vertical/Chimney Drain

Behind bridge abutments, retaining walls and reinforced earth walls, a vertical geocomposite drain replaces graded granular filter material and collects seepage before it can build up pressure on the wall. The water is led to an outlet pipe or weep holes at the base, so far fewer weep holes are needed than with a conventional filter.

Ocean Geocomposite has been supplied to GAIL (India) Ltd for gas pipeline works in Karnataka. Read about geocomposite for GAIL pipeline works at Bidadi.

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Ocean Non-Woven Pvt Ltd. manufactures geosynthetics including Ocean Geotextile, geomembrane products, geo bags, drain cells, geocomposites, geocells and geogrids, as well as solar panel pumps.