When It Rains… It Drains
16 07 2008The thing we love almost as much as the free food and pens at industry conventions, is seeing something exhibited that we have never seen before. That was definitely the case with the booth for the Ready Mix Concrete Association at Design DC 2008 last week.
The demonstration (pictured) was of something called Pervious Concrete. The material allows water to pass though the concrete reducing storm-water runoff, recharging groundwater, and contributing to sustainable design. Not only that, but builders can also get LEED certification credit for it’s use. The stuff seems like a no brainer for some of the asphalt jungles in our area!
i dunno. wouldn’t it make the ground all soggy, and turn dc back into the swamp that it once was?
very cool stuff!
My first thought is, if the concrete allows water in, what happens when the water freezes? Turns out that this hasn’t been fully tested in climates where the temperature regularly drops below freezing.
http://www.perviouspavement.org/inspection%20and%20maintenance.htm
Questions have been raised about the freeze-thaw durability of pervious concrete. Even though most experience with pervious concrete has been in warmer climates, recently there have been several pervious concrete projects in colder climates. Pervious concrete in freeze-thaw environments must not become fully saturated. Saturation of installed pervious concrete pavement can be prevented by placing the concrete on a thick layer of 8-24 inches (200 to 600 mm) of open-graded stone base. Limited laboratory testing has shown that entrained air may improve the freeze-thaw durability even when the pervious concrete is in a fully saturated condition. However, the entrained air content cannot be verified by any standard ASTM test procedure.