Geogrids

What Are Geogrids Used For?

Our strong and durable geogrids can be used to reinforce retaining walls, paving overlays, and other structures. The geometry of geogrid and variety of strengths, aperture dimensions, and rigidity means geogrids are incredibly useful for improving the structural integrity of soil structures and structures built on top of poor soils.

A geogrid is flexible, convenient, and durable. It shifts and deforms easily without damage, making it able to withstand the damage caused by shifting soils and helping it withstand the effects of small earthquakes.

Ground Stabilization With Geogrid

Geogrids have been in use for several decades as a way of stabilizing roads or sidewalks built on poor soils. Soft, sub-grade soil is often inadequate at handling heavy loads. Laying a geogrid provides a solid working surface upon which to build by interlocking with the surrounding fill material. In most cases, using a geogrid is more reliable and cost-effective than pouring concrete and offers better water drainage, too. Biaxial or triaxial polypropylene geogrid is the most common choice for ground stabilization projects due to its rigidity and strength in multiple directions, making it ideal for supporting heavy loads on soft soils.

Geogrids can extend the expected service life of sidewalks and roads, and provide higher stability and stiffness, enabling roads to accept heavier loads without issues. They're a low-cost and durable way of improving the surface quality of a new road.

Slope Reinforcement With Geogrid

Another common use of geogrid is slope and wall reinforcement. In these projects, typically, uniaxial polyester geogrid is used to create a reinforced soil mass which replaces the need for heavy expensive gravity walls. This is incredibly useful, especially on steep embankments where near vertical construction is not warranted but also in retaining structures. Geogrid interlocks with the facing units and the fill material in the structural fill zone creating a giant mass of reinforced material creating long lasting structrually sound civil structures.

Using geogrids in this way is cost-effective, because it reduces the requirement to have very thick retaining walls. In addition, it's a more environmentally friendly option, as you can use local materials for backfill, depending on their quality. This enables slopes and embankments to regrow natural vegetation more quickly.

Geogrid is available in a range of sizes and types, and it's important to choose the style that's best suited to your intended purpose. Engineers are generally involved in specifying the geogrid type and strength. Some geogrid have a high tensile strength in just one direction, while others are designed to be strong in all directions but are relatively stiff. The end use, type of soil in the area you're working, and the size and angle of any structure or embankment, influences your choice of grid.

Types of Geogrids

There are three types of geogrids: uniaxial, biaxial, and triaxial.

Uniaxial Geogrids

The higher tensile strength of uniaxial geogrids is in the machine direction. Uniaxial geogrids are mainly used for soil reinforcement in a segmental retaining wall or steepened slope. Uniaxial geogrids are usually woven or knitted from polyester yarn into a strong structure with a polymeric or PVC coating, making them resistant to strain, creep, and natural chemicals. Extruded uniaxial geogrids are made from HDPE.

To install uniaxial geogrid in retaining walls, roll the material perpendicular to the wall. The embedment length will be determined by the wall’s height, the conditions of the subgrade and soil, and the supported load and will be specified by the designing engineer.. Always pay attention when rolling the geogrid out, as uniaxial geogrid’s strength is in the machine direction which means the strength is in the length and should be rolled back into the hillside from the wall. Also, make sure not to splice or join 2 pieces of geogrid together trying to reach a certain embedment depth as there should be a single continuous piece of geogrid from the face of the wall to the back of the reinforcement zone.

Biaxial Geogrids

For raised patios, walkways, highways, parking lots, and access roads, biaxial geogrids are the most common type. Using square holes and a more rigid structure, biaxial geogrid increases soil load capacity since they have similar tensile strength in the two directions and have limited creep. These geogrids are used for reinforcing the base and the subgrade. In unpaved or paved applications, they minimize rutting and maintain the cumulative depth.

Unlike uniaxial geogrid, biaxial geogrid carries similar strength in both directions. You’ll want to install biaxial geogrid as deep into the surface as you can with at least 6” overlap between the pieces. This lets the aggregate interlock, preventing the base materials and subgrade from moving under the pavement surface’s load.

Keep in mind, however, that there are diminishing returns after about 12”, wherein you’ll likely need to install an additional layer of geogrid. When using this type of geogrid as a separation layer between the subgrade and the base, non-woven geotextile is recommended to prevent silt from migrating into the base with heavy traffic.

Triaxial Geogrids

With triangular apertures and reinforced ribs, triaxial geogrids may appear differently than biaxial geogrids but generally perform and are installed in a similar way as biaxial geogrids and are used in the same applications as biaxial geogrids.