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All about geotextiles

Products | March 17, 2022 | By:

Ocean NoOcean Non Wovens Pvt. Ltd. provides a detailed overview of geotextiles, which are useful for many infrastructure projects.

Close up photograph of geotextile roll from Ocean Non Wovens
Geotextile roll. Photograph courtesy of Ocean Non Wovens Pvt. Ltd.

A geotextile is a geosynthetic material used to improve soil characteristics. It can separate, filter, harden, protect and drain water when used in conjunction with soil. Geotextiles are suitable for many infrastructure projects, including roads, harbors, dumping sites, dumping structures and many other construction projects.

Geotextile types

Geotextiles are made of polymers such as polyester and polypropylene. They are divided into three categories according to how they are manufactured:

1. Woven geotextile

2. Nonwoven geotextile

3. Knitted geotextile

Woven geotextiles

The most common geotextile is woven and is produced by adoption techniques such as weaving standard textile fabrics. Woven geotextiles feature two sets of matching threads or strings. A long-running thread is called a warp and another perpendicular thread is called a weft.

Close up photograph of woven geotextile from Ocean Non Wovens
Woven geotextile. Photograph courtesy of Ocean Non Wovens Pvt. Ltd.

Nonwoven geotextiles

Manufacturers produce nonwoven geotextiles from continuous filament fiber or short-staple fiber. Threading is done using thermal, chemical or mechanical techniques, or a combination of techniques.

Geosynthetic fibers obtained from mechanical or chemical compounds or thermal composites have a thickness of 20–40 mil (0.5–1 mm) while nonchemical bonds, relatively thick in comparison, are typically 120 mil (3 mm) thick.

Close up photograph of nonwoven geotextile from Ocean Non Wovens
Nonwoven geotextile. Photograph courtesy of Ocean Non Wovens Pvt. Ltd.

Knitted geotextiles

Geotextile manufacturers produce knitted geotextiles by tying a series of threads together. All knitted geosynthetics are created using knitting techniques in line with other geosynthetic practices, such as weaving.

Diagram of geotextile yarns from Ocean Non Wovens
Diagram of yarns in a knitted geotextile. Illustration courtesy of Ocean Non Wovens Pvt. Ltd.

Puncture resistance

Geotextiles prevent objects or stones from exploding or pushing on other objects. Nonwoven geotextiles have high piercing resistance, which is necessary to prevent construction damage during the installation and placement of filling materials with sealing equipment. Woven geotextiles usually have very low puncture resistance and often (obscure) injuries occur during installation resulting in reduced performance or long-term failure. Strong puncture resistance involves pushing a 2 inch (50 mm) wide plunger into the geotextile and measuring in kilonewtons (higher is better). Strong puncture resistance involves dropping the cone into the geotextile and measuring the hole size in millimeters (lower is better).

Geotextiles from Malaysia are woven by crossing yarn, thus, creating a strong bond and making them stronger and more durable than nonwoven geotextiles. However, nonwoven geotextiles have a much greater elongation (more than 50%) than woven geotextile (between 5% and 25%).

Life expectancy

In experiments, the service life of fiber geotextiles is longer than that of polypropylene geotextiles; fiber geotextiles can last more than 50 years. However, the life of the geotextile fabric can be extended up to 20 years with various treatments and combinations.

Properties and test methods

Geotextile structures are divided into the following groups: physical, mechanical, hydraulic, tolerant and degradable. Tests for each group include experiments showing different aspects of geotextiles and their functions. In addition to these structural groups, geotextile testing may be considered an indication of performance. The index test is used for a general presentation of a geotextile product and does not provide values ​​that can be used directly for design purposes, while performance testing provides information about the expected behavior of engineered geotextiles.

Physical properties are used to express geotextiles in an accepted, structured and obtained state by reference index testing. Typical visual structures include specific gravity, unit size, thickness and durability.

The mechanical properties provide an understanding of geotextile strength and pressure under various loads. Typical mechanical properties include compression, tensile strength, tear strength, puncture strength and seam strength. A variety of tests are available to determine geotextile strength, usually designed to depict the conditions encountered in field installations.

One of the most essential strength properties of a geotextile is tensile strength. Geotextile tensile strength is measured by tying the opposite ends of a geotextile sample to a machine test and stretching the template until a failure occurs. In general, both the energy applied to the geotextile and the types of geotextiles are measured, allowing the observation of the stress-strain curve and the development of a compatible module. Several tests are available to measure the strength of geotextile tensile, with the main variations depending on the type of clamp used and the geotextile template size. The grab tensile test, ASTM D4632M, is a strong geotextile strength that is often specified and reported. It involves testing a diameter of 3.9 inches (100 mm) wide by 5.9 inches (150 mm) long geotextile specimen.

Other geotextile strength tests focus on making sure the geotextile is strong enough to withstand the pressures of installation, often the heaviest pressures placed on the geotextile during its lifetime. The tests that are usually specified are tears and piercing. The penetration strength of a geotextile is measured by making small cuts in the adjusted pattern and by using a solid test machine. The puncture strength is tested by measuring the force required to strike a probe through a geotextile specimen. ASTM D4833 is the standard specification for puncture strength.

This article first appeared on the Ocean Non Wovens Pvt. Ltd. website.

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