Interest in Pervious Concrete Grows

By Curt Grandia | September 28, 2010

Interest in pervious concrete continues to grow in the Midwest as specifiers learn more about its properties and benefits.

"I get at least two or three calls every week on potential pervious concrete projects," said John Cunningham of the Iowa Ready Mixed Concrete Association a little more than a year after the porous mix debuted with initial demonstration projects in the four states. "Pervious concrete is very hot right now, the hottest topic out there."

The Iowa Ready Mixed Concrete Association (IRMCA) is among several organizations in the area responding to the high interest with contractor training sessions and opportunities for certification.

IRMCA has several demonstrations and trainings scheduled this spring and also coordinates contractor certification through the National Ready Mixed Concrete Association (NRMCA). "Ready Mix producers invite their contractors and we do the training," Cunningham explained. "After the training, there is an exam that we send off to NRMCA for scoring and certification.

"The thing that contractors need to know is that specifiers, the architects and engineers, are requiring NRMCA certification for contractors who want to bid on pervious concrete projects," Cunningham said. "So there has to be someone from the company who is certified and will be on the paving job."

Another thing contractors need to know is that placing pervious concrete requires specialized equipment, including a roller screed, cross roller and joint roller — items not typical for the majority of area contractors. To ensure that the equipment will be available for pervious concrete projects, contractors should make arrangements with their equipment providers in advance to rent or purchase the equipment.


Pervious Concrete

Pervious concrete is a mix of coarse aggregate, cement, water, and little to no sand. The mix creates a porous, open-celled structure that allows rainwater to filter through into the ground.

Used especially for parking lots, sidewalks, driveways, and recreational trails, the 15-percent to 25-percent void structure of pervious concrete allows as much as eight gallons of water per minute to pass through each square foot.

That drainage or filtering reduces stormwater runoff, eliminates the need for retention ponds, replenishes water tables and aquifers, reduces demands on sewer systems, and minimizes flash flooding.