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 Given the size of potholes across much of Canada this spring, it’s probably hard to imagine that any municipality would want to build pavement with holes in it. However, the day might be coming sooner than you’d expect.
Of course, it’s not the wheel-eating sized potholes that are desirable, but rather, tiny spaces in the pavement that allow rainwater to soak in, and percolate through, rather than rushing off into a nearby storm sewer.
Permeable forms of pavement, and particularly pervious concrete, have captured the interest of Canadian developers and municipalities over the last year.
Capable of filtering rainwater through to underlying soil at a rate of about 200 litres per minute in a square meter, pervious concrete can potentially reduce demand on stormwater management systems, return naturally-cleansed water to underground aquifers and minimize flash-flooding, stream pollution and erosion issues.
“We’re seeing interest from all kinds of sectors,” says John Hull, president of the Ready Mix Concrete Association of Ontario. “It’s a product that’s actually catching us by surprise, in terms of demand.”
 The merits of pervious or permeable concrete have already been discovered south of the border. A number of American municipalities are using the material for sidewalks, bike paths and parking lots, while the Environmental Protection Agency has recognized its use as a Best Management Practice.
In Chicago, an initiative called Green Alleys will see about 1,900 miles of small service streets throughout the city refurbished with permeable concrete to allow rainwater drainage. Nearly 50 alleyways were refurbished last year alone.
Although there seem to be few large-scale examples of the use of permeable concrete yet in Canada, Carolyn Campbell, executive director of Ready Mix Concrete Association of British Columbia agrees that interest is growing rapidly.
The association will be offering a certification course in pervious concrete installation beginning in September. The product is installed differently than a traditional concrete, and requires some training and specific equipment, said Campbell.
Unlike traditional concrete, pervious concrete contains little in the way of sand or fine aggregate. Instead, mainly coarse aggregate is bonded with cementing materials, leaving gaps or voids that allow water and air to pass through. Although not as strong as traditional materials, pervious concrete can be used for a number of purposes, including parking lots, low-volume roadways, tennis courts, pool decks and pedestrian paths.
“With people looking for greener solutions, I think it’s a natural fit,” says Campbell.
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