Geotextiles physical properties

There are several different processes and polymers used ia the manufacture of geotextiles which affect their appearance and physical properties. Geotextiles are produced ia various weights and thicknesses, which also determine their physical properties and ultimately the performance of the material when iastaHed on a project (see also high performance fibers). 

Physical property tests on geotextiles and geonets must be designed to assess different uses, weights, and thicknesses of these materials, as well as construction methods used in the field. Some tests for geonets and geotextiles recommended by U.S. EPA are listed in Table 26.8. 

Even though separation may not be the primary function for which the geotextile is installed, in almost every case the geotextile does perform as a separator. For the separation function, the physical properties of concern are primarily strength-related, including wide width, puncture resistance, and tear resistance. 

Areas where geotextiles are used as reinforcement include embankment construction, reinforced soil wall construction, and slope improvement. In reinforcement, the physical properties of importance are primarily related to strength, that is, a combination of the stress—strain characteristics of the material. 

John, N. (1987), Paulson geosynthetic material and physical properties relevant to soil reinforcement applications. Geotextiles and Geomembranes, 6,211-212. 

Physical properties of geotextiles are basic properties related to the composition of the materials used to fabricate the geotextile and include the type of structure, specific gravity, mass per unit area, thickness, and stiffness. 

Geotextiles offer various properties that we can categorize into three main families the physical properties refer to the dimensional characteristics of the product. Mechanical properties refer to the behaviour of the geotextile when it is subjected to mechanical constraints. Hydraulic properties describe the behaviour of the geotextile in the presence of liquids or gases. The key properties of geotextiles are defined in Table 3.2. 

Table 4.4 Important physical properties of vegetable fibres used in geotextiles... 

Both woven and nonwoven geotextiles are made from four polymeric materials (polyamide, polyester, polyethylene, and polypropylene) and natural materials. Woven geotextiles may be fabricated with monofilament yams, muldfilament yams, or a combination of each. Nonwoven geotextiles are bonded by one of the several methods thermal, mechanical, or chemical. With the many combinations of materials and processes, it is not difficult to see that the physical properties of geotextiles will vary greatiy among products (Yeo, 2008). 

Another change could occur related to the use of thickness properties. Currentiy in Europe, the thickness of geotextiles is used in calculations for filtration potential. More widespread use of this practice could make thickness, not just a physical property measured for manufacturing quality control, but as a performance tool. 

Some good methods currently exist to measure the physical properties of geotextiles. Many of these were developed to satisfy the needs of the solid waste industry. However, because geotextiles have become more widely used in other applications and because they have evolved and developed to support those applications, it would be useful to know and understand some additional physical properties. Efforts should be expended to develop standardized tests for additional products and properties. 

It is well documented that polyolefins, which include polyethylene (PE) and polypropylene (PP), may degrade via reaction with oxygen. A geotextile s oxidation resistance depends strongly on the specific polymer, the stabilizer package, and the product s physical properties such as thickness and the surface area to mass ratio. 

Construction quality control and CQA consist of the physical properties of the geotextiles as they are manufactured but also the skill with which they are installed. In addition to the type of testing specified previously for MQA, this testing may include sewn seams, heat-tacked seams, and repairs of any defect that results from installation of the material. 

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