More on Pervious Concrete
A previous blog entry “Escaping the Hardship of Hardscapes” was an introduction to pervious pavement. Here we get a little more in depth.
We hear a lot about impervious surfaces such as parking lots, creating run-off that can be detrimental to both human and environmental health. One of the solutions being used increasingly is pervious concrete.
Pervious concrete uses many of the same ingredients that normal concrete uses- cement, water and gravel. The main difference is that little to no sand is used in the production of pervious concrete. This creates voids that allow water to flow through the pavement quickly. Typically, 15-25% voids are achieved, which allows for the flow rate of water through the concrete to be between 3-8 gallons per minute per square foot. The water is then stored in a coarse gravel layer underneath or allowed to percolate into the underlying soil.
So the main question: Is porous concrete strong enough to be do the job of normal concrete?
The answer is yes. Normal concrete used for pavement has an average compressive strength ranging between 3,000 to 5,000 psi, which is the same for pervious concrete. While it cannot be used for all applications, it can be used for a wide range of projects. The most common applications include parking lots, driveways, sub-division streets and sidewalks. Unfortunately, pervious concrete is not a viable option for highly traveled pavement. Pervious concrete has a rough textured, honeycomb surface, so when there is a large amount of traffic on this concrete, tire shear can loosen the aggregate on the surface.
Watch for an upcoming article about the special maintenance procedures needed for pervious pavements!