Geotextiles needle-punched nonwovens

Principle appHcations of needle-punched nonwovens for the 1990s include automotive, apparel components, blankets, carpeting, carpet pa dding, coating substrates, filtration, furniture, geotextiles, insulation, roofing substrates, and wall coverings. In 1990, the production of needle-punched fabric was estimated to approach 91,000 t and 606 million square meters (15). 

In nonwoven geotextiles, the fibers are much thinner but far more numerous. The various types are needle-punched, resin-bond, and melt-bond. All contain a labyrinth of randomly oriented fibers that cross one another so that there is no direct line of flow. The fabric must have enough open space to allow liquid to pass through, while simultaneously retaining any upstream movement of particles. The needle-punched nonwoven type is very commonly used as a filter material. 

In gas-collector systems, either a granular soil layer or a needle-punched nonwoven geotextile is placed directly beneath the LML or clay of a composite cap system. Gas compatibility and air transmissivity are the design factors that must be considered. Methane, the most predominant gas, should be compatible with most types of geotextiles including PET, PP, and PE. 

With the needle-punched nonwoven geotextiles, the water can move in both the vertical and horizontal directions. The nonwoven geotextiles can provide a drainage function by transmitting liquid within the plane of their structure. This means the flow is predominant in the lateral direction, and this is important in assessing the in-plane hydraulic properties (Kopitar, Skenderi, Rukavina, 2014). 

Rawal, A., Anand, S., Shah, T. (2008). Optimization of parameters for the production of needle punched nonwoven geotextiles. Journal of Industrial Textiles, 37(4), 341—356. Rawal, A., Patel, A., Sharma, V. K., Saraswat, H., Sayeed, M. M. A. (2013). Damage analysis notch sensitivity of hybrid needle punched nonwoven materials. Textile Research Journal, 53(11), 1103-1112. 

In a totally different application, the US Forest Service began using needle-punched nonwoven geotextiles as wraparound walls in steep logging terrain in the Pacific Northwest in 1974. The fabric rolls were sometimes delivered by helicopters. Geotextile-reinforced embankments were constructed in Alaska beginning in 1975... 

GTX-Nl Polypropylene heat-bonded nonwoven geotextile, continuous filaments, 150 g/m. GTX-N2 Polypropylene needle-punched nonwoven geotextile, continuous filaments, 200 g/m. GTX-N3 Polypropylene needle-punched nonwoven geotextile, st 5>le fibers, 200 g/m. GTX-N4 Polypropylene needle-punched nonwoven geotextile, st 5>le fibers, 1200 g/m. ... 

RoUin, A.L., 1983. Characteristics of needle punched nonwovens and their influence on filtration behaviour in geotextiles. In Proceedings Conference on Nonwoven Fabrics, UMIST, Manchester, UK, 1983. 

Geotextiles. Nonwoven fabrics have played an important part in the development of geotextile appHcations. Both needle-punch fabrics... 

Drainage or fluid transmission Allowing water (or vapour) to be transmitted in the plane of a thick nonwoven needle-punched geotextile or a drainage geocomposite. 

Table 8.3. Permissible heights of fill (specific weight 11.8 kN/m ), when individual particles with a maximum particle size d ax he on or under a 1.5 mm thick HDPE geomembrane and this is protected by a protective nonwoven needle-punched geotextile of mass per unit areaM. If the mass per unit area is undershot or the surcharge is exceeded, pimcture of the geomembrane can be expected...

Nonwoven fabrics have played an important part in the development of geotextile applications. Needle-punch fabrics manufactured from either staple fibers or spunbonded continuous filaments have found worldwide acceptance on the basis of field performance. In 2000, it is estimated that North America consumed approximately 300 million m of geotextiles (62). 

Nonwoven geotextiles are composed of directionally or randomly oriented fibers which are mechanically (needle punching), chemically, or thermally bonded into a loose web. 

An impressive example of the performance of such a last defense line behind a beach nourishment is the wrapped sand containment needle-punched composite geotextile (woven PP slit film and nonwoven PET) to reinforce a dune on the island of Sylt (North Sea, Germany) is shown in Fig. 21.8. 

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