Woven geotextiles

Wound dressings Woundhealing Woven fabrics Woven geotextile... 

Fig. 2. Photomicrographs of geotextiles made by various methods (a) woven geotextile, (b) needle-punched, (c) heat-bonded, and (d) resin-bonded.

FML placed on a bed of sand, geotextiles, or other highly permeable materials would allow liquid to move through the defect in the FML, spread over the whole area of the clay liner, and percolate down as if the FML was not there. With clay liner soils that contain some rock, it is sometimes proposed that a woven geotextile be placed on top of the soil liner under the FML to prevent the puncture of rocks through the FML. A woven geotextile between the FML and the clay, however, creates a highly transmissive zone between the FML and the clay. The surface of the soil liner instead should be compacted and the stones removed so that the FML can be placed directly on top of the clay. 

Woven geotextiles. A woven fabric consists of two sets of orthogonally interlaced filaments or staple-fibre yams. The weave design or pattern is determined by the manner in which yams or filaments are interlaced. Filaments or yams placed in the longitudinal and transverse directions are known as warp and weft, respectively. Monofilament and slit woven geotextiles are anticipated to be thinner in comparison to multifilament, spun, and fibrillated woven geotextiles. 

Kabeya H, Kannokor AK, Kamata Y. Influence of surface roughness of woven geotextiles on interfacial Motional behaviom-evaluation through model experiments. Textile Research J 1993 63 604-10. 

Ariadurai SA, Potluri P. Modeling the in-plane permeability of woven geotextiles. Textile Research J 1999 69 345-51. 

Figure 8.1 indicates that geotextile structures include continuous sheets of non-woven, woven, and warp knitted fabrics, and stitch-bonded fibres or yams. The woven and warp knitted materials can be made to have a similar structure to certain of the textile-related products (essentially geogrids) to be used as alternatives. The non-woven geotextiles can be combined with the textile-related structures to make geocomposite products that are multifunctional. 

Non-woven geotextiles are fibrous sheets in which the fibres can be almost randomly orientated. These materials may be manufactured from either staple fibres (synthetic or natural) or continuous filaments of PP or PET which are randomly distributed in layers onto a moving belt to form a web of assembled fibres blends of PP and PET staple fibres are also used. 

Table 8.2 Comparison of needle-punched and thermally bonded non-woven geotextile properties...

The characteristic opening size or pore size, O95, and the pore-size distribution of a non-woven geotextile are determined not only by the quantity of the fibres forming the web and the intensity of bonding used, but also by the fibre diameter, or diameters, and their orientation in the web. Various mathematical models for pore-size prediction have been derived based largely on the open spaces viewed normal to the plane of the deposited web layers. 

Research studies - have shown that the compressive characteristic of non-woven geotextiles typically follow a hysteresis curve as depicted in Rg. 8.19, which can be represented by the following equations respectively for compression and recovery. 

Instead of considering the largest particle diameter that can pass through a given void space, the hydrodynamic pore size may be used for predicting the hydromechanics of non-woven geotextiles. If the void is assumed to be equivalent to a circular flow channel, then the hydrodynamic pore size may be defined by its hydraulic radius, Rh, where ... 

Woven geotextiles are produced from synthetic-fibre yarns, mainly PET or PP, and natural fibre yams, largely jute or coir, such as the Sulzer projectile loom P7150, used to produce woven fabric in widths of 190-540 cm. ... 

Woven geotextiles have the appearance of two sets of parallel threads interlaced at right angles to each other in the plane of the fabric. Warp yarns lie along the length of the fabric and weft in the transverse direction, i.e. across the width of the fabric. The type of yarns used to produce a woven geotextile may be monofilament, multifilament, a combination of each type, or slit film yarns. Two kinds of slit film yarn can be used, either flat-tape yarns or flbrillated yarns. 

In weaving, the warp and weft yams are commonly referred to as picks and ends. The interlacing of the picks and ends gives a coherent structure, and the repeating pattern of the interlacing is referred to as the weave of the fabric. Woven geotextiles are commonly plain weave, but twill weave and leno weave are also used. ... 

Plain weave is the simplest interlacing pattern, as shown in Fig. 8.22 for jute and coir woven geotextiles in the length of the fabric a warp yam crosses over alternate wefts, and in the fabric width, a weft yarn crosses alternate warps. The frictional contact of the yarns at the interlacing points prevents each yarn slipping from its woven position, and it also increases the stiffness of the fabric. The interlacing causes the warp and weft yarns to have a... 

The areal weights of woven geotextiles can be from 70 g/m 2 (for lightweight synthetics) to 1400 g/m- (heavy weight natural geotextiles). 

Comparison of woven and non-woven geotextile tensile properties. 

Both woven and non-woven geotextiles can serve as moisture barriers when impregnated with bituminous, rubber-bitumen, or polymeric mixtures. Such impregnation reduces both the cross-plane and in-plane flow capacity of the geotextiles to a minimum. However, for liquid containment applications, what is referred to as a GCL will be more effective. 

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