Down to earth solutions for geotex

Non-woven geotextiles is the general term employed to describe a wide range of synthetic materials used in geotechnical engineering. It is also synonymous for a range of specialist FEHRER technology.

Non-woven geotextiles can perform both hydraulic and mechanical functions, either simultaneously or separately. Their hydraulic functions include drainage with thick, very porous materials and filtration, using a geotextile with a high voids ratio in direct contact with the soil to prevent natural erosion and uplift.

The first mechanical function of a geotextile is separation, in which the mechanical characteristics and properties of two soils with differing particle size distribution and behaviour are preserved, preventing interpenetration under loads and subsequent deformation. Secondly, thick, fibrous geotextiles are utilised to absorb and evenly distribute stresses and thereby act as a shield against the perforation of impervious films, sheets, asphalt membranes and other materials. Finally, high-tenacity geotextiles placed in soil can take up some of the tensile stress and spread it more evenly.

Such geotextile webs can be produced from staple fibres or filaments. In general, polyester and polypropylene, both singly and in blends, within the 3.3 dtex/40 mm to 6.7 dtex/70 mm range are used. Then the webs are either thermally, chemically, or mechanically bonded. The latter is where FEHRER technology plays a crucial role.

Mechanical bonding involves the needling process, which offers a sizeable range of advantages. Above all, mechanical bonding does not alter the basic material and the bonding points constitute flexible connections. These create a very pliable product with a high deformation capability. Mechanical bonding can also be applied independently of the fibre employed.

FEHRER's geotex technology range is bound to impress

FEHRER machinery offers high, continuous production speeds with working widths of up to 8.0 m. The company's geotex lines are notable for their straightforward operation, low power consumption and floor space requirement. In addition, production is most environment-friendly due to the avoidance of harmful by-products and the possibilities for recycling waste and defect material.

FEHRER geotex lines come in a variety of configurations and technologies to match specific requirements. There are aerodynamic random web forming lines such as the
V 21/R -K 12"HIGH-LOFT" combination, which process the fibre from the preparation plant into highly uniform, totally randomised webs with a well-balanced MD:CD strength ratio and capacities of over 1,000 kg/h, depending on the working width.

In the needle punching sector, the NL 9/S - H1-V line is equipped with a special inlet system and advanced"H1" needling technology and can be integrated with the NL 21/R for upstroke finish needling to secure uniform fibre entanglement across the web, and the NL 21 for downstroke needling aimed at obtaining the highest punching densities. In addition, FEHRER also supplies cutting and winding machines according to the individual line layout. This system incorporates gentle handling of the pre-web, an isotropic strength ratio and optimum finish needling.

Lastly, FEHRER spunbond lines can incorporate NL 3000 and NL 3000/R machines, with continuous operating speeds of over 3,000 strokes/min, which are required due to ever-increasing performance of the filament spinning heads. Single-board NL 2000/S and NL 2000/RS machines, with continuous stroke frequencies of up to 2,200 rpm are also available for spunbond production. These are ideal for heavy duty production at high speeds, or using high-density needling.

Geotextiles are utilised in road construction, drainage systems, embankments, roofing, tunnels, coastal protection, landfills, construction, irrigation, sports fields and engineering biology. These, and other applications, as well as the increasing pressure for infrastructure development and ecological protection, have all resulted in a steady expansion in the demand for geotextiles. Growth echoed by sales of FEHRER lines to leading producers around the world.