Geotextiles are permeable fabrics which, when used in association with soil, have the ability to separate, filter, reinforce, protect or drain. As the use of geotextile fabrics has expanded there has been the introduction of geotextile composites and the development of products such as geogrids and meshes. Overall these materials are referred to as geotextiles and related products. All have a wide range of applications and are currently used to advantage in many civil engineering applications including roads, airfields, railroads, embankments, retaining structures, reservoirs, canals, dams, bank protection and coastal engineering.

Geomembranes are impermeable membranes used widely as cut-offs and liners. Until recent years, geomembranes were used mostly as canal and pond liners; however, one of the largest current applications is to the containment of hazardous or municipal wastes and their leachates. In many of these applications geomembranes are employed with geotextile or mesh underliners which reinforce or protect the more flexible geomembrane whilst also acting as an escape route for gases and leachates generated in certain wastes.

The range of products and their applications has expanded rapidly over the last decade with geotextiles and geomembranes being specified world wide. This rapid growth is paralleled by a virtual explosion of technology. Current reference books and even manufacturers' sponsored publications tend to date very quickly and the need for a vehicle to bring together and discuss the growing body of technology now available has become evident.

Geotextiles and Geomembranes fills this need and provides a forum for the dissemination of information amongst research workers, designers, users and manufacturers. By providing a growing fund of information the journal increases general awareness, prompts further research and assists in the establishment of international codes and regulations.

THE TYPES OF GEOTEXTILE

In general, the vast majority of geotextiles are made from polypropylene or polyester formed into fabrics as follows:

• Woven monofilament
• Woven multifilament
• Woven slit-film monofilament
• Woven slit-film multifilament
• Nonwoven continuous filament heat bonded
• Nonwoven continuous filament needle-punched
• Nonwoven staple needle-punched
• Nonwoven resin bonded
• Other woven and nonwoven combinations
• Knitted

 RAW MATERIAL OF GEOTEXTILE

The four main polymer families most widely used as the raw material for geotextiles are:

1. Polyester
2. Polyamide
3. Polypropylene
4. Polyethylene