What are Geogrids?

What are Geogrids?

Geogrids are geosynthetic material made from polypropylene, polyethylene or polyester. They are used in several civil engineering related applications to provide ground reinforcement.

Global Synthetics geogrids are manufactured from the extrusion, weaving or welding of a polymer to form open aperture products of varying strength, strain and load carrying capability for applications of soil reinforcement. Generally geogrids have a primary strength in one direction only (uniaxial geogrids) although in certain applications the strength may be equal in both directions of the product (biaxial geogrids). Geogrids work by interlocking with the granular or soil material placed over them. The open apertures of the geogrid allows for confinement of the material within, thereby increasing the shear strength of such materials.

Biaxial Geogrids

In the application of base reinforcement in pavements there is the design intention of improving the bearing capacity of an existing sub-grade by including one or more geogrid layers above. The inclusion of a biaxial geogrid generally permits a reduction in granular base course thickness.

In some situations, there may be a requirement to increase the service life of the pavement by the inclusion of a geogrid for a fixed pavement depth.

Global Synthetics offer Secugrid® biaxial geogrids in a range of strengths between 20kN/m to 80kN/m and Combigrid® geogrid/geotextile composite in the same strength grades.

Uniaxial Geogrids

The ACEGrid® high performance geogrid range, are engineered products for applications of short term and long soil reinforcement. The product is woven with strength in both the roll length direction (commonly called the machine direction-mD) and with strength manufactured in the cross roll direction (commonly called the cross direction-CD). Generally the strength of the product will be dominant in one direction of the roll (normally the mD) with sufficient strength in the other direction of the fabric (normally CD) such that the fibres are dimensionally stable and the roll may be easily deployed.

In applications of soil reinforcement the use of ACEGrid® engineered geogrids allows significant tensile strength to be imparted to soils. Soils are very weak in tension. the use of soil reinforcement techniques has proven to be a very cost effective method of construction. ACEGrid® engineered geogrids are manufactured from high tenacity polyester (pEt) fibres with high molecular weights and low carboxyl end groups such that the product is suitable for use in normally occurring soil types, for design lives in excess of 120 years. ACEGrid® high performance geogrids are available in a range of strengths from 40kn/m to 900 kn/m tensile strength

Asphalt Geogrids

Vehicle traffic loading on asphalt and concrete pavements including temperature variations imposes higher stress/strain on the pavement leading to the development and propagation of reflective cracking. The main function of asphalt geogrids used in the construction and rehabilitation of roads pavements subjected to thermal, fatigue and reflective cracking is to reduce the amount of cracking in the new asphalt layer(s). In addition, a barrier to top-down water ingress to the subbase and/or subgrade may be provided. Global Synthetics, has an extensive range of products suitable for asphalt pavement construction which includes asphalt reinforcement geogrids / geocomposites (made from Polyester (PET) or Glass Fibre) for the retardation of reflective cracks and stress cracking associated with joint interfaces.

Common Applications for Geogrids

Global Synthetics biaxial geogrids are designed to interlock with soil and aggregate and are ideal for applications such as:

• Base and subgrade reinforcement
• Construction of unpaved and paved roads

Global Synthetics uniaxial geogrids are designed to provide long term design strength and are ideal for applications such as:

• Reinforced slopes
• Embankments

Base/Subgrade & Rail Ballast Reinforcement – Challenging ground foundations within both the roads and railways corridors is extremely common and can lead to deep and expensive treatment remedies without geosynthetics. Global Synthetics, has an extensive range of high strength and durable geogrids / geocomposite products (made from Polypropylene (PP) or Polyester (PET)) for subgrade stabilisation on soft and expansive subgrades and stiffening of road and railway asset structural layers. Geogrid reinforcement provides interlocking with gravel, rock and ballast materials to confine the lateral movements in the overlying structural layers and in most cases can provide up to 30% reduction in depth. Furthermore, geocomposite products with a non-woven geotextile offer the additional benefits of separation and filtration benefits coupled with the stiffness and strength of a geogrid for gravel reinforcement and stabilisation of trafficked areas. Ultimately, creating a sound working platform needed for compaction, improving the subgrade bearing capacity, stiffening the gravel structural layers, controlling differential settlement, reducing the risk of cracks and deformations/rutting. The performance benefits in extending the life of the asset and history over many years within the Australian and broader international markets takes precedence when compared to other alternative products and easily provides asset owners with a sustainable and economical solution.