Geosynthetic materials include a broad range of polymer, and other materials which are increasingly used to provide economic solutions in a variety of civil engineering applications. The major groups of geosynthetic products are geomembranes, geotextiles and geosynthetic clay liners. Other geosynthetic products include geogrids, geonets and geocomposites. Jaylon has had considerable experience over more than 20 years in project applications involving each of these product types.

Geomembranes

Geomembranes represent the largest group of geosynthetic products. Geomembranes are impervious thin sheets of polymeric material used primarily for linings and covers of liquid storage facilities. The membrane’s containment function is to perform as a liquid or vapour barrier. Selection of the correct geomembrane material, or combination of materials, is of critical importance and includes consideration of climatic conditions, ultraviolet exposure, substrate stability, the substance being contained, and the service life required. Other considerations such as project location, site conditions, field installation circumstances and installation area also need to be taken into account. The following are the most common polymeric materials used for geomembrane linings and covers:

Polyvinylchloride (PVC)

PVC is the most workable of all geomembrane materials. Panels up to two thousand square metres in area can be prefabricated and transported to site for installation. PVC offers superior puncture resistance and withstands contact with strongly acidic or caustic substances. Applications include leach pads, dams, ponds, residue areas, tanks and ornamental landscape watercourses. PVC membranes are particularly suited in applications where off-site fabrication is possible, when surface preparations are less than ideal and the geomembrane material is not exposed to ultra violet radiation for a lengthy period. It is not recommended in organic or hydrocarbon applications, in ponds or tanks containing marine life, or where full exposure to sunlight over long periods is expected.

High Density Polyethylene (HDPE)

HDPE offers excellent ultraviolet resistance, wide-ranging chemical resistance and because of its sheet width can be cost effective over large areas. HDPE in commonly used thicknesses is a comparatively inflexible geomembrane material, and is almost always seam-welded on site utilising specialised welding equipment. It is therefore not recommended for small or intricately shaped installations. As HDPE is inflexible it is not suitable in applications where substrate stability is uncertain.

Polypropylene (PP)

Reinforced and unreinforced PP offer ultraviolet and chemical resistance properties approaching those of HDPE, yet its flexibility is similar to PVC, enabling prefabrication into panels up to two thousand square metres in area. PP is ideally suited for applications requiring long life in harsh conditions, particularly where substrate stability cannot be assured. PP’s puncture resistance features makes it suitable for applications where a smooth substrate surface cannot be prepared. Common PP applications include floating covers, landfill liners and caps, dam liners, tank liners and sewerage processing ponds.

Polyethylene (PE)

In thicknesses down to 200 microns, premium-grade PE is a flexible geomembrane material available in wide-widths. It is ultraviolet stabilised and can be expected to last up to twelve months in an exposed environment. This light-gauge geomembrane is generally suited to short-term applications.

Geotextiles

Geotextiles are woven, matted or knitted products constructed from synthetic fibres which are not susceptible to biodegradation. Geotextiles are porous and accordingly allow liquid flow across their manufactured planes and also within their thickness. There are a wide range of applications for geotextiles but the primary functions performed by this group of geosynthetic products are protection, separation, reinforcement, filtration, drainage and containment (when impregnated).

Geosynthetic Clay Liners

Geosynthetic clay liners are factory-fabricated thin layers of naturally occurring bentonite clay, generally sandwiched between two geotextiles, or alternatively bonded to a geomembrane. The product is often needle-punched, stitched, fibreglass reinforced or physically bonded to assist with structural integrity. GCL’s are often used as part of a composite liner system in conjunction with a geomembrane, as well as in isolation. GCL’s suit a range of environmental and containment applications, especially when absolute performance is critical and when unwanted penetration risks are present. GCL’s are often used in preference to compacted clay due to their superior performance and cost effectiveness.

Other Geosynthetic Products

Other commonly used Geosynthetics include Geogrids (used almost exclusively as reinforcement materials), Geonets (to convey liquids of all types within a drainage system) and Geocomposites (a combination of the Geosynthetic product types outlined above).