Geosynthetics

Geosynthetics are synthetic fabrics which are sufficiently durable to last a long time in any environment. Geotextiles and Geomembrane are the two major products of geosynthetics.

1. Geotextiles

Geotextiles are porous fabrics manufactured from synthetic materials that are primarily petroleum products and others such as polyester, polyethylene, polypropylene and polyvinyl chloride, nylon, fibre glass, and various mixtures of these. They are manufactured in thicknesses ranging from 10–300 mils (1 mil = 0.0254 mm), widths up to 10 m and roll lengths up to about 600 m. Geotextiles are termed filter fabrics and have permeabilities comparable in range from coarse gravel to fine sand.

Geotextiles have been used in a variety of civil engineering works. The four major functions for which geotextiles are used are soil separation, filtration, drainage and reinforcement.

2. Geomembranes

Geomembranes are thin materials with very low permeability. They are flexible and are manufactured from synthetic or bituminous products. They may be strengthened, if necessary, with a fabric or film. Geomembranes differ from geotextiles with reference to the rate of permeability. The permeability is high (as in sand) in geotextiles and very low in geomembranes (as in colloidal clay). For all practical purposes, geomembranes may be considered to be impermeable to both gases and fluids. This makes them ideal for constructing of water-proof or gas-proof barriers between adjacent bodies of soil or soil and fluid. Geomembranes are used for sealing against fluid percolation and buffers against pollutants.