What are Geosynthetics?

Geosynthetics are defined as polymers shaped into planar materials for the purposes of reinforcing and improving soil conditions. The planar definition refers to the fact that these materials are primarily available in large flat or curved sheets. Geopipes are a notable exception because they’re tubular, but almost all other geosynthetics are planar and designed to cover flat and curved surfaces. With such a broad definition, this category includes over a dozen different designs and materials. Each type of geosynthetic usually shares characteristics and functions with multiple other options, and some of them work best when used together in the same project. Explore the dozens of important uses for geosynthetics to identify if your project is a good candidate to take advantage of the benefits.

Common Types

There are dozens of distinct types of geosynthetics, but many of them overlap enough to fall into general categories. Some of the most common types of these materials include:

  • Geonets- sheets of flat polymer strands that cross over each other to create a repeating diamond or circular pattern. These nets are divided into biplanar and triplaner designs depending on how many angles make contact with the soil. The geonet category is highly related and overlaps often with geogrids and shares some similar features with geomembranes. This material is extruded rather than woven or matted together. Geocells and geocups are a similar type of geonets with much larger openings to capture units of soil between extruded loops.
  • Geogrids- finer mesh sheets with small gaps between flat or molded strands of a polymer. The net-like design is similar to window screen mesh or fish netting. Larger openings between the strands result in better connection to large soil particles, while fine mesh screens are ideal for allowing for drainage without allowing soil migration. These nets can be produced through weaving, knitting, and extrusion methods, depending on the raw material used.
  • Geomembranes- solid and impermeable sheets of flexible polymers design for keeping water contained. Pond liners and similar lining products all fall into this category. Other types of flat and solid geotextiles may look similar, but only geomembranes control both liquid and vapors for complete isolation of certain materials. Whether you need to encapsulate, cap, or seal something, a flexible membrane made from a material like reinforced polyethylene (RPE) is a good choice.
  • Geotextiles- may look similar to geomembranes but feature a more fibrous or yarn-like composition. Polymer-based materials are still used, ensuring longer service life than woven products made from natural sources. These textiles are highly porous, unlike geomembranes, and allow water to seep through layers of soil without destabilizing it. Non-woven geotextiles are also available, and these materials generally feature smaller openings than you would find in extruded grids. The fabric-like surface is rough enough to grip against the soil, creating friction to prevent sliding and collapse.
  • Geosynthetic clay sheets- a product combining the natural sealing power of bentonite clay with layers of geomembranes and/or geotextiles. The clay layer is glued or sewn to the other geosynthetics, creating an effective barrier for blocking water flow and preventing erosion. Since the bentonite clay expands rapidly upon exposure to moisture, it provides a long-lasting stabilization method that adheres well to natural soils. The clay material is often modified with particles of polymers or fibers to increase its soil strengthening abilities.
  • Geofoam- soil stabilizing blocks and sheets made from expanded polystyrene foams. The insulating power of these geosynthetics makes it easy to keep water or other fluids from freezing or to prevent the freeze cycle from damaging concrete slabs. Soft soils that tend to become saturated in the winter are often reinforced with sheets or blocks of geofoam before soil beds are installed over the surface.
  • Geopipes- an advanced form of the corrugated polymer pipes widely used in roadway and soil stabilization techniques for drainage. Since these plastic pipes are so widely used in soil stabilization and ditch drainage applications, it’s commonly referred to as geopipe. Drainage applications range from simple French drains to protect building foundations to mining systems that also function as filters to protect the ground water. These pipes are more corrosion and clog-resistant than their metal and concrete counterparts.
  • Geocomposites- a unique combination of geotextiles and reinforcing mesh or grids. These geosynthetics are primarily used as basket drains to trap contaminants and dissolved solids before they can travel through the underlying soil layers. Lining ditches and edge drains with a composite geosynthetic product is often the only option for controlling erosion on a steep slope where other materials don’t achieve proper adhesion.
  • Other products, including polymeric soil sprays, threaded systems, and various soil anchors.

Popular Uses

With over a dozen different categories of geosynthetics, there are hundreds of current uses for these materials in a variety of industries. The private and public roadway industry makes the most use of geosynthetics since they’re used in the roads, for stabilizing ditches and slopes, and for preventing erosion. Farms of all kinds also make good use of geomembranes and geotextiles to prevent runoff and soil seepage from creating contamination issues. Fertilizer and manure runoff are a hazard to natural waterways and drinking supplies, but impermeable liners and geomembranes prevent this from becoming a health hazard or causing environmental damage.

New construction services also make generous use of various geosynthetics, including geomembranes, geogrids, and geotextiles. Installing a layer of the right water-blocked geomembrane liner or soil stabilization grid can make a foundation much more stable by preventing soil shifting. Since new construction often generates plenty of runoff to create erosion or flooding risks, geopipes and drainage filters are commonly used as well to stabilize soft and sandy soils. Landfills require geosynthetics during both the initial installation, as a bottom liner, and during closing as a water-proof cap. This prevents dangerous runoff from soaking into the groundwater below. A geomembrane cap further reduces how much water mixes in with the trash to create more runoff. These geosynthetics must offer high levels of durability, tear resistance, and chemical resistance to qualify for landfill use. Finally, all industries that require reliable liquid containment now rely on geosynthetics like geomembrane liners. This includes mining, manufacturing, power generation, and even fish farming.

Benefits of Using Geosynthetics

Most geosynthetics are designed to interlock with the soil particles of raw ground in some way. This creates a tight bond that adds as much strength as possible to the soil. In road and construction projects where loose soil could move suddenly due to constant stresses, the bridging effect of a planar material prevents cracks and ruts from forming. The same is true for construction projects where foundations are at risk of shifting or settling. Geogrids and similar products are affordable options for erosion control and slope stabilization, costing far less per square foot than alternative methods. These materials work well in a wide variety of settings, from paved and unpaved roads to ponds and drainage areas. Easy installation speeds up the creation of new projects and aids in renovation processes when dealing with eroding slopes or leaking dams. With so many potential benefits for each project, it’s no wonder the majority of designs involving geosynthetics use more than one material.

Growing Support from Engineering Tests

During the first decade of of geosynthetics, these materials weren’t widely used due to a lack of research into their durability and best uses. Now that they’ve been used in real life roadway and construction applications for over 40 years, there’s plenty of engineering research to back up their uses. It’s no longer a guessing game to determine if a particular material or method will hold up for years or not. Simply look up the relevant data based on your project and see what science confirms as the best method for stabilizing soil. From delamination tests on geocomposites and clay sheets, to puncture tests for geomembranes, there’s hard data on anything you need to know about geosynthetics.

Geosynthetics allow you to make the most of any soil, even when it’s too soft or unstable in its natural state for your desired purpose. Laying down the right geomembrane or geotextile can stabilize the surface, prevent shifting, and control water movement through the ground. If you don’t see your desired use listed here, there’s still plenty of options for adapting these materials to brand new uses. Discuss your options for geomembranes with us here at BTL Liners.  Our expert team members are readily available to provide more information on putting our liners to good use.

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