Pervious Concrete Pavement – Lets Water Soak Into the Ground
Filed Under: Green Technology on July 22, 2009
Pavement has a major down side when it comes to ground water: it forces the water to run off, usually by channeling, and thus doesn’t let a lot of it soak into the ground. Most water coming off of pavement will run in rivulets into streams, sewers, and so forth. This deprives groundwater sources of some of their renewal sources.
Well, Pervious Concrete has a solution for that. They’ve developed a Pervious Pavement that allows water to soak through into the ground beneath it. This porous concrete meets EPA stormwater regulations and is even recommended by the EPA as a Best Management Practice.
For most uses, such as parking lots, the concrete is actually cheaper because installation can forego the usual runoff designs and stormwater management devices like retention ponds or spillways. The down side, of course, is that this concrete is not as strong as normal, solid concrete, but it is strong enough to be used for low speed and light load applications like standard car parking lots and pedestrian walkways.
The way it works is deceptively simple: the concrete is mixed with a high aggregate content (gravel) and less sand than usual. This creates a mortar bond between the gravel pieces, but does not make a solid sheet of concrete. This allows for the formation of a 15-25% void ratio in the finished concrete.
This will be pervious (porous) and typically allows a 5/gallon per foot per minute
water flow through the concrete and into the ground beneath.
If installed correctly, the concrete is resistant to freeze-thaw cracking, oil seepage from leaking vehicles, and is easily cleaned by pressure washing or brushed sweepers. It’s only real down side is that strength issue, which can be somewhat overcome to accommodate vehicles up to tractor-trailer size, just not at speed.
Pretty cool!
Related posts:
- Energy Generating Pavement from Pavegen
- Collecting Kinetic Energy in a Parking Lot
- Bendable Congrete That Heals Itself Too
