Why use a Geogrid?

Why use a Geogrid?
The correct use of a geogrid can offer many benefits to a scheme such as increasing the speed of construction, and/or reducing the quantity of soil thatneeds to be exported from / imported to a site. Common uses of geogrids include increasing the amount of usable land on a site by enabling construction of steep greenslopes or walls, enabling construction of a road over poor ground conditionsordecreasing the thickness of fill required to construct a road.

How are Geogrids manufactured and does this make a difference?
Currently there are three categories of geogrids available:

The first, and ‘original’, geogrids are commonly referred to as ‘punched and drawn’ geogrids. A sheet of either HDPE or Polypropylene has holes punched into it in a regular pattern and the sheet is then ‘drawn’ or ‘stretched’ into the finished product.

The drawing is done under controlled conditions of temperature and strain rates to avoid fracture whilst allowing ductile flow of the molecular chains. This operation aligns the molecular chains in the direction of drawing to convert low-strength polymer into high-strength grids.

The second category of geogrids is ‘coated yarn’ types. They are, in fact, technical textiles in the form of grids and use bundles of fibres (most commonly Polyester) as the reinforcing component that are then coated to provide protection during installation and in service. The grid structure is formed by knitting or intertwining the transverse and longitudinal bundles of fibres.

The third category of geogrids is made by laser or ultrasonically welding together polyester or polypropylene rods or straps (as used in packaging / shipping) in a grid like pattern.

Does the method of manufacture make a difference?
Yes. The different methods of manufacture create products that look and feel quite different.It therefore follows that the different forms of geogrid will work with the soil to perform the reinforcing function in differing ways.

There have been numerous studies into the performance of geogrids. These have concluded that whilst there are a number of mechanisms which enable a geogrid to function, the principal and most effective mechanism is lateral restraint or confinement of the compacted fill that is interlocked within the grid.
The best type of geogrid for mobilising this mechanism is a ‘punched and drawn’ geogrid such as E’GRID geogrid.