Geotextiles

Geotextiles are used with foundation, soil, earth, and rock material as an integral part of man-made project, structure, or system. Geotextiles are a permeable geosynthetic comprised solely of textiles. Geotextile materials prevent the erosion of earth and similar substances after the area has been altered due to construction usually pertaining to civil engineering applications such as roads, pavement, bridges, embankments and retaining walls. They allow the passage of water but not soil and other materials.

Geotextile Testing: In order to determine if a geotextile material is suitable for a particular application it must undergo appropriate mechanical testing procedures. The most common forces a geotextile experiences during its application are tensile and puncture. Each of these forces can cause the premature failure of a geotextile and lead to catastrophic events.

Common Test Methods: The most common geotextile testing methods are wide widthtensile testing, puncture and puncture resistance testing, and tensile grab testing. Each method requires a specific setup and is used to evaluate different characteristics of the material. A wide width tensile test is a common tensile test in which a rectangular test sample is placed into a tensile testing machine so that each end is held in a grip and then the grips are moved apart so that the sample is loaded in tension until rupture. However, for geotextiles the sample is generally designed to be wider than it is long, because during its application large sections of the material will be subjected to tensile forces.

Puncture and puncture resistance testing measures the geotextiles ability to withstand the penetration of sharp or point objects such as sticks, twigs, pipes or poles.A grab test is very similar to a tensile test in that it is designed to measure the reaction of the material as it is essentially stretched; however the key difference is that instead of loading the material vertically it is loaded horizontally.

Geotextile Testing Specimens: Geotextile test specimens are generally simple to make as they are usually just squares or rectangles cut straight from the material. Depending on the test that will be performed on it the sample will be somewhere between two to eight inches wide and four to eight inches long. Geotextiles come in three basic forms: woven (resembles fabric), punched(resembles felt), and heat bonded (resembles ironed felt). The most common materials to make geotextiles are polypropylene and polyester.