CLEVELAND (AP) A project involving a kind of concrete meant to prevent the dirty backup of pollutants from rainwater and storm sewers is drawing the attention of construction and government officials who gathered Aug. 24 for a demonstration.
The old thinking is that concrete used in the north should be smooth when it goes on and dry solid to withstand the constant pounding of auto, bike and pedestrian traffic, and the freezing and thawing of harsh winters.
With 200 construction industry leaders and government environmental officials looking on, workers finished pouring a patch of a parking lot that is 50- by 12-ft. behind the bookstore at Cleveland State University (CSU) downtown. They used pervious concrete that looks more like a rice cake –– tiny holes inside allow water to seep into the ground instead of rolling into gutters or backing up on roads.
Pervious concrete has been used in warmer climates, but it was shunned in places such as Cleveland because of fear that winter weather would cause it to break it into pieces.
The CSU project and other research at the school and elsewhere around the country hope to dispel such concerns.
After successful lab studies, field trials are needed now, said Vern Schaefer, a professor of civil engineering at Iowa State University.
The hope is the project will help researchers collect information that will lead to greater understanding of pervious concrete, said Norb Delotte, associate professor of civil engineering at CSU. He’s also working with the American Concrete Institute on pervious concrete guidelines.
“Civil engineering is a very conservative profession,” Delotte said. It doesn’t pay to rush into something that may ultimately prove fallible, he said.
The effects of salting and plowing on pervious concrete also will be monitored at CSU. Delotte said ground-penetrating radar will be used to gauge moisture levels in the concrete and ultrasound may be used to measure the concrete’s integrity over time.
A project in Kent showed the substance has potential. The city installed pervious concrete on two parking spaces at its Fred Fuller Park in the fall of 2003. So far, it’s holding up well with water passing through and no change in the concrete, said Charley Bowman, community development director.
Besides the storm-water benefits, which could help meet tighter Environmental Protection Agency regulations, pervious concrete is supposed to be several degrees warmer in winter, reducing the need for plowing, Bowman said. And it’s supposed to be several degrees cooler in the summer.
Standard concrete, approximately $3.50 per sq. yd. to install, is made from stone, sand, cement and water.
Pervious concrete has the same ingredients except sand. The absence of the fine particles is what creates the voids in the concrete. It costs approximately $1 more per square yard said Don Wade, a Florida-based salesman of Magruder Construction Co. of Eolia, Mo.
Tom Cahill of environmental engineering firm Cahill Associates of West Chester, PA, said pervious pavement of various kinds is the way of the future.
“We’re going to try to build a world that is more permeable,” he said.