When engineers need to build a retaining wall to secure the sloping sides of a highway base, they might build a structure out of concrete that attaches to the slope using a grid that extends into the hillside. This process can be pretty expensive, mostly because the facing on that concrete, which makes the wall more appealing when you drive by it, can cost a lot. It's heavy, and it has to be shipped in. Plus, concrete often doesn't weather all that well.
EnviroGrid doesn't require an extension deep into the slope, so it can be easier to install. More importantly, it can be filled with aggregate already on site, so shipping costs are minimal. It's flexible, so the ground is secured in a more natural state. And because the open honeycomb structure allows for water flow and drainage, vegetation can compose the pretty top coat, instead of something like concrete.
Retaining walls, which are used not only for roadways but also in landscaping, landfills and all sorts of other civil engineering projects, are just one geocell application. Erosion control and ground stabilization are the other two primary uses for EnviroGrid.
Ground stabilization is the application the geocell approach was initially developed for, and it turns out civilians need stable ground as much as soldiers do. Laying a grid of geocells on unstable earth and filling it with dirt or rocks can create a stable foundation for a driveway, a park walkway or a hiking trail. It can make soft ground fully support foot traffic, a golf-cart path, a sewer system or train tracks without sinking in under the weight.
And securing the ground takes on a much "greener" bent when you get into erosion control. Applying the EnviroGrid framework to a stretch of land in danger of aridity from wind and water erosion, or a hillside that's getting steeper and steeper or a river bank that's disappearing into the river can stop and even reverse the erosive process. It's used a lot in parks and hiking areas to keep the land stable despite human use. The geocells hold the land in place to prevent further erosion, and you can fill the cells with new, seeded soil, which can both build up the land and promote re-vegetation to keep it that way.
The unique structure of the geocell makes it ideal for re-vegetation because it lets water flow freely, even between cells if the grid material is permeable. It's a very flexible technology, though. For a more heavy-duty wall against erosion, you can simply pour concrete into the cells.
For more information on EnviroGrid and related topics, look over the links below.
Related HowStuffWorks Articles
- "Bodcell™ Geocell Erosion Protection." Boddingtons. http://www.boddingtons-ltd.com/civil/geocell-erosion-protection.htm
- "Cellular Confinement." EnviroGrid.http://www.envirogrid.com/cellular_confinement.html
- "MULTICELL® Cellular Confinement System (Geocell)." Weismann-Friedman Industry.http://www.wfi.co.il/cellular.asp