Nonwoven geotextiles manufacturing processes

Nonwoven geotextiles. Nonwoven fabrics are defined as a sheet, web, or batt of directionally or randomly oriented fibres/filaments, bonded either by friction, and/or cohesion, and/or adhesion. In general, nonwoven fabric formation can be considered as a two-step process web formation (aligning the fibres with certain orientation characteristics) and bonding these fibres by mechanical, thermal, or chemical means. This two-step process has formed the classification of nonwoven structures, i.e. carded, airlaid, spunlaid, meltblown, needlepunched, hydroentangled, adhesive bonded, thermal bonded, stitch bonded, etc. Some of the important processes that are used for the manufacture of nonwoven geotextiles are discussed below. 

The specihc stmcture of each type of nonwoven geotextile, which is a result of the manufacturing process, has a direct impact on the capacity of the geotextile to perform its function in the soil. Table 3.5 shows in greater detail the main relationships of the manufacturing process, the structure of the geotextile and its performance in the functions for which it is adapted. 

Nonwoven geotextiles are formed by the bonding of random arrays of synthetic fibres (see chapter Geotextile manufacturing processes). Fig. 20.1(b) shows the typical random stmcture of nonwoven geotextiles which commonly are composed of polypropylene fibres but can also be composed of polyester fibres. 

Figure 3.2 Nonwoven geotextile manufacturing process flowchart.

Natural geotextiles are generally manufactured in the form of woven fabrics and nonwoven matting structures or as a combination of both woven and nonwoven structures. A general sequence of processes for producing natural geotextiles is shown... 

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