What is a geogrid, its definition, application, uses and examples of materials
A geogrid is a two-dimensional mesh manufactured from high tensile polymers with a fixed aspect ratio. They are constructed from geosynthetic yarn. The geogrid has intersecting ribs that can withstand pressure by redistributing the vertical load across its junctions. Between the intersecting joints is a void, known as aperture. Depending on the manufacturer, the aperture, thickness of the geogrid and the tensile strength of the geogrid can vary.
Geogrids have been in use for several decades now, and have evolved into the most soil reinforcement materials which can be used for a variety of civil engineering works. Geogrids are popularly made from polyester, polyvinyl alcohol, polyethylene or polypropylene. At Strata Geosystems, our, geogrids are coated with a proprietary coating that makes them durable in physical and chemically aggressive environments.
The core function of a geogrid, which is different from a geocells, is to provide high tensile load bearing support due to its two dimensional structure. Compared to geocells, geogrids can withstand much higher vertical pressure, while stabilisation and locking the aggregate, or subgrade material. Due to this lateral restriction, which is at equidistant junctions, geogrids are more flexible. Depending on the aggregate or subgrade material, geogrids also improve the soil interaction leading to a stable subgrade, with easier water movement. This is particularly helpful for terrains prone to water logging. The mechanism of geogrids is to confine the material. Due to this, reduced lateral movement, they affect the angle of internal friction of the subgrade, or soil, allowing better redistribution of loading, which in reduces the amount of settlements and deformations in the soil or subgrade.
There are three types of geogrids: uniaxial, biaxial, and triaxial. Each type provides different benefits for soil reinforcement, load bearing and distribution, minimisation of soil deformation, and low creep factor which is useful for planar reinforcement. It’s the apertures which contain the subgrade material, or soil holding it in place.
As the name describes, uniaxial geogrids provide reinforcement in a singular direction since all its ribs are oriented in one direction, providing high tensile strength. It’s therefore used in applications such as retaining walls, or steep slopes.
A biaxial geogrid on the other hand offers reinforcement in two directions with equidistant ribs that intersect each other: latitudinal and transverse. As a result of this bi-directional pull, it’s preferred in applications where reinforcement is needed in multiple directions to provide higher load distribution and stability over larger surface areas such as pavement stabilisation, or soil retention.
The triaxial geogrid provides support across its length, breadth and width. It provides tensile strength in three directions, and is preferred for soil stabilisation for highways and road construction.