General Geogrids

Use & Purposes

• Access Road Construction
• Crane & Rig Platforms
• Pavement Support

Highlights

• Ease of Product Handling
• Geogrid Interaction Characteristics
• Geogrid Strain Characteristics
• Wide Roll Width

General Information

Geogrids are polymeric products formed by joining intersecting ribs. They have large open spaces also known as “apertures”. The directions of the ribs are referred to as machine direction (md), orientated in the direction of the manufacturing process or cross machine direction (cmd) perpendicular to the machine direction ribs. Geogrids are mainly made from poly – meric materials, typically polypropylene (PP), high density polyethylene (HDPE) and polyester (PET).

Product Information

In the application of base reinforcement there is the design intention of improving the bearing capacity of an existing subgrade by including a geogrid (or layers of geogrid) over the in-situ subgrade to minimise the amount of granular material needed in the base course (or pavement) design. 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.

The preferred geogrid in such applications is a biaxial “stiff” high modulus product. Global Synthetics are able to offer Secugrid® which is a low strain biaxial (equal strength in both directions) geogrid with higher strengths than most other geogrids at strain levels of 1%, 2% and 5%. Stiffer geogrids pick up load more quickly and consequently operate at strain levels appropriate to pavement performance levels.

Applications

There are several major markets for geogrids. These are base reinforcement, earth retaining wall construction including veneer stabilisation, the segmental retaining wall market, embankment reinforcement and pile cap platforms. Biaxial geogrids are primarily used in base reinforcement applications. The base reinforcement market is just what the name implies. These are applications where an engineer is trying to improve the performance of a gravel base over poor soils, trying to minimise the amount of gravel in the base course design, or increasing the life of
the surface cover, concrete or asphalt. Geogrids such as Secugrid® are used under parking lots, airport runways, gravel construction roads, highways, dam levees and railroad
tracks.

Benefits of Secugrid®

• True biaxial geogrid with equal strengths in both the machine and cross machine direction which
  allow stress transfer in all directions, e.g. in road curves.
• Strength – Higher strengths than most other geogrids @ 1%, 2% and 5% strains.
• Modulus – Very high modulus which means this product will pick up the stresses quickly with little or
  no movement in the overlying base materials.
• Wide rolls will translate into less overlaps. In a large flat area this will result in less material required and save overall costs.
• Resistance to installation damage – Installation damage testing is performed on geogrids to see what, if any, damage occurs to the geogrid during installation.

Secucalc Software 

To assist you in your design, this software has been designed to allow a generic calculation of aggregate base material in unreinforced and Secugrid®, reinforced applications, such as under roadways, access/haul roads, parking lots or similar applications. Secugrid® geogrid reinforcement extends project service life, improves performance, reduces excavation, and lowers overall costs. SecuCalc 2.2 is based on test trials and 30+ years of engineering knowledge. For further information click here:

Case Study

Combigrid® – Hardstand in Brisbane

In 2011, TRANSCITY was selected as the contractor to design, construct and operate the Legacy Way Toll Road in Brisbane’s west. Legacy Way, once complete, will connect the Western Freeway at Mount Coot-tha with the Inner City Bypass at Kelvin Grove.

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