Geotextiles are the largest category of geosynthetics and are widely used in many applications of geotechnical engineering. They are divided into woven and non-woven, according to their manufacturing process. Woven geotextiles are mainly used for separation and reinforcement applications, whilst non-woven geotextiles functions are filtration, drainage and separation of different soil layers and geomembrane protection. The wide range of geotextiles which are commercially available is due to the differences between the raw materials used, types of yarns and manufacturing method of the final product.
In general, each manufacturer produces either a single type of geotextile (available in different thicknesses or mass per unit area) or a variety of types of geotextiles that each is intended for a specific application.
The raw materials (polymers) used for the manufacture of geotextiles are polypropylene (most common), polyester, polyamide (nylon) and polyethylene.
The Role of Non-Woven Geotextiles
The tensile resistance of geotextiles in combination with their impact and puncture resistances, contribute to the absorption of the various stresses that develop during constructions. Geotextiles protect sensitive materials from damages and deterioration and enhance the conservation of the rigity of the structure.
Although the geotextiles are permeable, the pore opening size is maintained sufficiently small, so as to create an effective barrier between the different soil layer types and to prevent their mixing.
The structure of geotextiles allows the unhindered passage of water through their mass, while retaining fine soil materials. The specific structure prevents contamination of granular filters.
The structure of needle punched non woven geotextiles ensures flow through the mass, both horizontally and transverse (transmissivity, permittivity), to effective drain constructions.