Nonwoven Geotextile – Choosing the Right Geotextile for Your Construction Project
Often confused with wovens, non woven geotextiles provide excellent strength and durability. They also allow for great drainage in projects that have pools or standing water.
Rather than being woven together like a woven geotextile, non-woven fabrics are manufactured by needle punching or chemical bonding techniques. They are made of synthetics and are best used for filter or separation applications, as well as protecting a geomembrane from interior or exterior penetrations.
Filtration
When choosing a non-woven geotextile for your construction project, there are many factors to consider. Grab tensile strength, elongation, trapezoidal tear resistance, CBR puncture resistance, and permittivity are just a few of the important specifications to consider. These values indicate the fabric’s overall strength and performance, but the fabric’s permeability and filtering properties are particularly important.
Woven geotextile fabrics are made by traditional weaving of individual threads on a loom to create a large, uniform piece or sheet. Different materials can be used, including slit films, monofilaments, and fibrillated yarns. While woven geotextiles have high load capacities, they are not as permeable as non-woven fabric and are thus a poor choice for drainage projects.
The pore size distribution of the geotextile’s filtration channel is a key factor in determining its filtration ability. For the woven and spunlaid fabrics, pore size is determined by a process called sizing. This involves sizing the filaments or short fibers and then either drawing them into long strands, or bonding them together with thermal, chemical, or mechanical means.
The resulting strands can then be spun into a variety of shapes and sizes. These can be used to construct a geotextile, or they can be further processed to create specific performance characteristics. For instance, needle-punched nonwovens can be shaped into a geotextile that is ideal for soil stabilization and erosion control.
Separation
Woven geotextiles are often used for erosion control, soil stabilization and drainage. They can also be placed under hardscape projects like gravel driveways to prevent rutting and intermixing of aggregate with the soft soil underneath, and they reduce or eliminate the need for costly base rock. Wovens are highly tensile and resistant to UV degradation, so they’re well suited for long-term applications.
Wovens are commonly manufactured using a twisted yarn process called warp knitting or weaving, but some nonwoven producers use chemical methods to fuse fabrics together without weaving them. Needle punching and hydroentanglement are two common techniques for bonding nonwovens into self-locking and coherent fabric structures.
Nonwovens are often referred to by their weight, but their performance isn’t dependent on their size. They’re a great option for separation, drainage and filtration projects because of their high tensile strength, low Flood control sandbags permittivity and small openings. They can be made of a variety of materials, but are typically based on polypropylene for durability.
Generally, lighter weight nonwovens are used for separation and drainage. They’re popular under paver patios or walkways to prevent mud; outdoor areas where cows or horses are allowed to exercise to keep the area free of muddy conditions; stream crossings in light traffic areas; and as a layer under playground mulch. Heavyweight wovens are recommended by the AREMA standards for railroad ballast, and they can be used under asphalt overlay fabric to increase pavement life.
Reinforcement
Woven geotextile membranes can be used in stormwater attenuation tanks, protecting the liner from erosion while also allowing for separation and filtration. Unlike their woven counterparts, non-woven geotextile membranes are needle punched, making them a better choice for applications that require both separation and filtration.
While woven and non-woven geotextiles are both made from synthetic textiles, they differ in their structure. Woven fabrics are characterized by the interlocking of individual fibers, which gives them a distinct “fuzzy” appearance. Non-woven geotextiles are produced by bonding instead of weaving, through chemical, heat, needle punching or other methods. These geotextiles are often made from polypropylene and are best suited for filter or separation applications. They are also more effective than their woven counterparts at protecting geomembrane lining systems from interior and exterior penetrations.
Non-wovens are also less expensive than wovens. They are typically referred to by weight, with the industry standard being 8 ounces per square yard (33.9 g/m2).
Woven and nonwoven geotextiles both have exceptional tensile strength. However, woven fabric’s tensile strength is more accurately measured by grab tensile testing, which clamps the specimen across its entire width and pulls it at a faster rate than standard full-width tensile tests. In addition, woven geotextiles are more likely to resist rot and corrosion when exposed to harsh chemicals, such as those used in oil and gas exploration.
Drainage
Drainage is an important aspect of a geotextile. The drainage capabilities of a geotextile can have a huge impact on how well it can be used in different applications. For example, a nonwoven drainage fabric can be placed underneath gravel/rock footpaths to prevent erosion and promote proper water flow. Another application for a geotextile is retaining walls. Woven and nonwoven geotextiles are both excellent choices for a retaining wall because they can provide separation, reinforcement, and drainage.
Woven geotextiles are made by weaving together individual threads into a sheet or large area of fabric. They can be woven with many different materials, including fibrillated yarns, monofilaments, or slit films. The weaving process makes woven geotextiles super strong, making them an excellent choice for load bearing applications. However, it also makes them less permeable than nonwovens.
Nonwoven geotextiles are manufactured by either Road reinforcement geocell needle-punching or poly-spun processes. This creates a more felt-like product that has high filtration and permeability rates. Nonwovens are more porous and can handle higher load capacities than wovens.
Nonwoven geotextiles can be broken down into three different categories based on their performance and environmental conditions: lightweight, medium weight, or heavyweight. When choosing a nonwoven drainage fabric, it is best to look at the fabric specification sheets and read about its grab tensile strength, elongation, trapezoidal tear strength, CBR puncture resistance, permittivity, and permeability.