Comparing Geotextiles

Comparing geotextiles, such as nonwoven polypropylene geotextiles, is one way to understand applications best suited for each type.

Geotextiles are synthetic textile materials made from polymers. They are porous fabrics that have been in use since the 1950s for erosion control. Today, geotextiles are used with soil and other materials to provide separation, filtration, reinforcement, protection, and drainage—and sometimes combined into composites for other geotechnical applications.

There are three categories of geotextiles: open-mesh or woven fabric, knitted, and closed fabric or nonwoven. Each type of geotextile carries unique benefits, making them better suited in different situations to provide filtration, drainage, separation, and stabilization.

This article focuses comparing geotextiles and highlights the benefits of each.

Open-mesh or woven fabric

The first type of geotextile is an open-mesh or woven fabric. Interlocking fabric strips make this geotextile into large, uniform sheets. Woven geotextiles typically offer a higher load capacity and are ideal for heavy applications such as roadway construction. Woven geotextiles are also associated with a concept known as Percent Open Area (POA). POA is the area of distinct openings of a geotextile not occupied by filaments. POA gives engineers a way to know the frequency of gaps in an area of the geotextile. While all geotextiles offer filtration and porousness, woven geotextiles emphasize clogging resistance through POA (1).

In exchange for their strength, woven geotextiles are not as porous and, therefore, not ideal for drainage projects. However, woven geotextiles perform well in separation and reinforcement applications due to their low permeability.

Knitted geotextiles

Knitted geotextiles are made by interlocking a series of loops of yarn together. They are available in two- and three-dimensional variations. The two-dimensional knitted geotextile uses warp-knitted fabrics looped into zigzag patterns and helps reinforce the soil for foundation improvement. The three-dimensional version utilizes in- and out-of-plane multiaxial reinforcement. Three-dimensional geotextiles, also called cellular geonets, are ideal for water drainage from the ground by providing a structure to hold aggregate such as asphalt (2, 3).

Knitted geotextiles make up a small percentage of the total geotextile market, though the demand for this geotextile has been growing. Finally, when comparing geotextiles, it is essential to mention nonwovens.

Closed fabric or nonwoven

Nonwoven geotextiles comprise polymers like polypropylene. Nonwoven polypropylene (PP) geotextiles benefit from resisting most chemical and biological media. This resistance makes nonwoven PP geotextiles ideal for separation, protection, and filtration purposes in roadways, railroads, landfills, and civil/environmental projects. Additionally, they can be UV-stabilized to provide longer service life under direct sunlight (4).

Engineers deploy nonwoven geotextiles in various environmental, civil, and mining applications for the filtration, separation, and protection of other geosynthetics. Nonwoven geotextiles carry the benefit of being easy to install and durable, thanks to their ability to retain dimensional stability throughout their service life. Engineers can also use nonwoven geotextiles to reduce soil requirements, which can be especially helpful in areas with poor soil or difficult-to-reach sites. The nonwoven geotextile also supports using aggregates for drainage in environmental, civil, and mining applications.

Sourcing your nonwoven geotextiles from AGRU

AGRUTEX is a nonwoven PP geotextile by AGRU that allows engineers to take care of filtration, drainage, separation, liner protection, and gas collection as part of an environmental liner system. The geotextile reinforces soil banks, promotes a firm base for roads and highways, lines ground drains, and prevents erosion along riverbanks and the coast. This geotextile contributes to applications that require high-quality products that exceed ASTM standards and government regulations for landfill and waste collection systems. AGRUTEX is also helpful in civil engineering applications such as roads, railways, river canals, coastal works, drainage, sports field construction, and agriculture.

A well-designed heap leach pad is essential to protect the environment and increase the ability to recover valuable ore from mining operations. A core component to most heap leach pads is a containment layer made with a geomembrane. AGRUTEX protects the low-permeability geomembrane liner from being punctured by the subgrade during the heap leach pad preparation. Additionally, engineers can incorporate AGRUTEX for filtration, drainage, and separation. AGRUTEX is available in a range of weight classes to meet most subgrade preparation requirements in this application.

Nonwoven polypropylene geotextiles like AGRUTEX are beneficial throughout a site’s service life. For example, after the heap leach pad is complete, AGRUTEX can provide filtering in solution trenching. AGRUTEX acts as a filter that finely sifts larger particulates from solutions collected as part of the operation in this application. When mining operations have finally ceased, and closure is necessary, engineers can utilize AGRUTEX with a geomembrane or a geocomposite product. AGRUTEX reduces the overall topsoil depth requirement by absorbing and redirecting moisture away from the existing soil by working with Drain Liner. AGRU Drain Liner is a drainage medium with built-in studs to help funnel water collected by the geotextile.