Soil stabilization is the backbone of strong, long-lasting roads, foundations, and other infrastructure. It ensures that soil can support heavy loads and resist shifting and erosion over time. Without it, our world’s infrastructure would crumble—literally.
To keep our roads, bridges, and buildings standing strong, engineers and contractors rely on soil stabilization products, including geosynthetic materials. In this blog, we’ll explore the four most common types of geosynthetics—geotextiles, geogrids, geocells, and geomembranes—as well as their uses, pros, and cons.
Geotextiles are permeable fabrics that reinforce, separate, drain, and filter soil to prevent erosion. They can be made from natural or synthetic fibers called polymers.
Geotextile Fibers |
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Natural |
Synthetic |
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Coconut husks |
Polyamide |
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Jute plant fibers |
Polyester |
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Paper |
Polyethylene |
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Wood shavings |
Polypropylene |
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Wool |
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Choosing a fiber is all about sustainability, longevity, or both. Natural fibers come from renewable resources, so they’re more sustainable than synthetic (plastic) ones. They also biodegrade in a few years—which is good if you want them to do that. For long-term soil stabilization, synthetic geotextiles can last 100+ years without breaking a sweat. Or, you can meet in the middle: treated natural fibers or blended fabrics last around 20 to 50 years.
Just like clothing or linens, you can categorize geotextiles by how they’re made: woven, nonwoven, or knitted. The manufacturing method may not seem like a big deal, but it’s crucial because it determines the types of projects on which each geotextile performs best.
Woven geotextiles intertwine fiber strands. They’re strong and durable, with few pores, so they keep soil in or out. That’s why they work well for separating soil layers or controlling erosion. They can also resist certain chemicals due to their high density, keeping unwanted substances out of soil.
Manufacturers lay out fibers and bind them together to make nonwoven geotextiles. You may hear people classify these materials based on the layout or binding method:
Nonwoven geotextiles are usually cheaper, lighter, and more breathable than woven ones. They’re great for jobs that require good drainage and filtration, such as landscaping, rip rap underlay, or pipe wrapping.
While knitting sounds like weaving, it’s a different process. Knitting interloops fibers to create a softer, more flexible fabric than woven geotextiles. And with more space between fibers, knitted geotextiles drain and filter soil well. However, they’re weaker and less chemical resistant than woven geotextiles, so they're best suited to gentler applications.
Geotextiles’ tensile strength evenly distributes loads to stabilize structures. They control erosion and drainage and are often more affordable than other soil stabilizers.
However, geotextiles are likely to rip during installation. And they’re not a good match for expansive clays, which filter water slowly and clog the fabric.
Geogrids are a framework of intersecting fibers with uniform open spaces—called apertures—between them. These spaces can be circles, triangles, squares, trapezoids, hexagons, or any other shape. The final product is a flat material that comes in a roll, somewhat like a roll of chicken wire.
Geogrids are made for heavier-duty soil stabilization, which is our specialty here at Substrata. They stabilize granular fills, like aggregate, by capturing them in the apertures to reinforce soil and distribute loads evenly.
Geogrid Manufacturing |
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Method |
Description |
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Extrusion |
Stretches the plastic and/or forces it through a die to achieve shape and strength |
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Weaving |
Interlaces the fibers; applies nodes where they cross to strengthen them |
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Bonding |
Lays out the fibers and coats them with plastic so they stick together |
Geogrids get their names from the number of ways they provide strength to the soil. Most geogrids are uniaxial, biaxial, or triaxial. Uniaxial geogrids offer one-way strength for simple projects, while triaxial geogrids offer three-way strength for complex projects. Let’s dig deeper into the specific types of projects you can complete with each geogrid.
Uni means one, so uniaxial geogrids provide strength in one direction. They have good longitudinal (lengthwise) strength but are weaker transversely (side-to-side). That makes them best at handling pressure from a single direction. So, contractors often use them in retaining walls, embankments, and slope stabilization where earth pushes outward on the grid.
Biaxial geogrids are longitudinally and transversely strong, so they’re better for projects where pressure moves in two directions. For example, vehicles push down on and pull across roads, so builders place biaxial geogrids in road and railway bases to distribute the load and reinforce the subgrade so it won’t shift under traffic. This increased strength permits a thinner layer of aggregate, reducing material costs.
Complex loads need more stability, and that’s where triaxial geogrids come in. Their triangular apertures create uniform strength in all directions. They’re the most stable geogrids and work best on complicated roads, railways, and heavy industrial areas. However, they require more material and advanced design, so they may cost more.
Geogrids have a high load-bearing capacity, a long lifespan, and low chances of deterioration. They retain aggregate well and can reduce construction costs by decreasing material use.
That said, geogrids can be pricey. Your installer has to really know what they’re doing since improperly laid geogrids can fail, causing erosion, shifting soil, or structural collapse. Finally, since they’re synthetic, they’re less sustainable than natural geotextiles.
Geocells are like geogrids on steroids: they’re stiffer, have much deeper apertures, and contain more material. These 3D, honeycomb-like structures are also known as cellular confinement systems since each compartment holds soil and/or aggregate in place to stabilize it. They come in panels that crews lay out and fix in place with stakes.
Geocells are the bubble wrap of the civil engineering world. Together, the cells create a sort of “mattress” that absorbs impact, increases tensile strength, and reduces surface erosion. Many companies use them to line vulnerable channels or protect hydraulic equipment. And in the Icelandic town of Siglufjörður (pronounced sig-loof-yee-ord-thur), geocells protect the village from avalanches.
Most geocells are made in the same way, from the same material. Manufacturers typically make them from high-density polyethylene, heat them via ultrasonic welding, and attach them to each other while they’re still warm. So, we classify them based on design: perforated or unperforated. Let’s explore the uses of each type.
Perforated geocells have small, evenly spaced holes in their cell walls. These holes drain water and disperse loads more evenly across the system. The perforations also allow for airflow and plant root growth. In fact, you can even use perforated geocells to protect tree roots from traffic loads in nearby parking areas.
With their solid, smooth walls, non-perforated geocells keep water out of material, making them more common for applications like landfills that need to separate liquids and soil. They work well for containing materials like sand or gravel without material loss or clogging.
Geocells work deeper underground than geogrids. They remain stable in challenging terrain, so they’re good for slope stabilization, erosion control, and riverbank protection projects. They’re especially popular for unpaved roads and parking lots. On paved roads, they strengthen the subbase to allow for a thinner layer of asphalt.
Installing geocells is labor-intensive and time-consuming since they require precise anchoring and infill. They cost more than other geosynthetics. And like all synthetic materials, they last for years but come from nonrenewable resources.
Geomembranes aren’t soil stabilizers in the same sense as geotextiles, grids, or cells. But since they’re closely related, we invited them to the party!
These synthetic, impermeable barriers keep liquids in or out of soil, water, and containers. Geomembrane liners keep ponds from leaking or landfills from leaching toxic waste into nearby soil. They even take the show on the road: they can line truck beds to contain materials during transport. While not strictly soil stabilizers, geomembranes can (and do) help hold soil in place. By separating soil and liquids, they prevent erosion and environmental disasters.
Geomembranes come in thin, continuous sheets. Manufacturers can customize their size to fit everything from a small goldfish pond to a football field. And if that’s not big enough, they can weld more sheets together.
Manufacturers classify geomembranes by material. The five main types are: high-density polyethylene, low-density polyethylene, polyvinyl chloride, ethylene propylene diene monomer, and bituminous. Certain materials work best in certain applications, so it’s crucial to choose the right type of geomembrane for your project.
HDPE geomembranes are most common thanks to their durability and chemical resistance. They’re good liners for landfills, underground fuel storage sites, slurry ponds, and hazardous waste containment areas. They’re cost-effective for large-scale, long-term projects. But their high density limits their flexibility and makes them more difficult to use in complexly shaped areas.
LDPE geomembranes are more flexible than HDPE due to their lower density, but that also makes them slightly less durable. They work best for temporary installations, small-scale water containment (like ponds), or irregularly shaped areas.
PVC geomembranes are highly flexible and easy to install, so they work well for temporary projects that need quick setup without long-term durability. That makes them good for temporary containment, as well as some canals and agricultural water storage units.
Ponds and reservoirs can benefit from EPDM geomembranes. They’re flexible and weather-resistant, making them ideal for exposed outdoor areas and aquaculture such as fish hatcheries or oyster farms.
Extreme climates require extremely tough solutions, and that’s where bituminous geomembranes come in. They’re durable, weather-resistant, and UV-resistant—which helps with sun-exposed projects such as dams or canals.
Geomembranes are impermeable, chemical-resistant, and highly customizable. They last for decades. They’re less likely to fail than clay liners and are possible to repair if they tear.
However, if roots or sharp objects do tear them, they may be hard to access for repairs. (Some manufacturers treat the membrane’s surface to increase friction, so it hopefully won’t shift or rip.) While cheaper than concrete, geomembranes can be expensive upfront, and they may wear out faster if they undergo frequent temperature fluctuations like freeze-thaw cycles.
One way to optimize your geomembranes is to pair them with another soil stabilizer, such as Perma-Zyme. That way, if the membrane rips or tears, you have another containment system in place—crisis averted!
Geotextiles, geogrids, geocells, and geomembranes serve distinct roles in soil stabilization and construction. Let’s recap:
These four geosynthetic materials have different designs and applications based on a given project’s stabilization or containment needs. You may find that geosynthetics are the best fit for your project, you may combine them with other methods, or you may find a different soil stabilizer that better meets your needs. The key is to know your options and choose what’s best for your project.
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