March 23, 2005
First used 100 years ago
Pervious concrete touted by B.C. group
By Cheryl Mah
DCN correspondent
Renewed interest in an old concrete technology could be the answer to today’s higher standards for stormwater management.
Recognition of the adverse environmental impacts of stormwater runoff and the general sustainability movement present the concrete industry with huge opportunities to promote innovative solutions, according to Carolyn Campbell, executive director of the B.C. Ready Mixed Concrete Association.
The association plans to actively promote the benefits of pervious concrete specifically to municipalities this year by showcasing installations and its effects.
Pervious concrete, originally used 100 years ago in Europe as structural insulation in buildings, is a unique product with a porous structure that allows rainwater to filter through the pavement and into the underlying soil naturally.
“There’s an interest to look at ways to reduce the amount of hardscaping that has taken place on both commercial and private construction,” says Campbell.
The lack of infiltration of impervious surfaces and subsequent stormwater runoff adversely impacts fish, water quality and the environment.
Pervious concrete was first used in Florida more than 20 years ago, but is relatively new to the West Coast.
“It’s really used extensively in the U.S.,” says Campbell. “And with the amount of rainfall in the Pacific Northwest, it’s just a tremendous opportunity here — less so in other parts of Canada.”
Unlike conventional concrete mixes, pervious concrete contains little or no fine aggregate and limited amount of cement paste.
“That’s what allows the gaps and the porosity of the concrete.
“It’s not what you put in, but what you leave out,” explains Campbell, adding the result is a concrete with a high volume of voids (20 to 25 per cent) and a high permeability.
Another selling point for the use of pervious concrete is the achievement of one point under the LEED system, Sustainable Sites Credit 6.1.
Pervious pavement can be used to help reduce the rate and quantity of stormwater runoff, says Campbell.
Not only is there renewed interest in the product environmentally but economically as well.
The cost of stormwater infrastructure and managing runoff is substantial, notes Campbell, and pervious concrete provides an excellent alternative to expensive stormwater collection and detention systems.
Compared to other stormwater management practices such as bioswales and retention ponds, pervious concrete also maximizes land use efficiency.
Pervious concrete replenishes ground water supplies, filters water naturally and by reducing the urban heat island effect, it helps to protect fish habitats too.
“We’re looking at promoting it as a viable means to reduce the temperature of runoff into salmon streams,” says Campbell.
Pervious concrete can be used in a variety of paving applications to provide hardscape without altering the hydrology of the land — a benefit that has been recognized by landscape architects.
“People like landscape architects just love this,” says Campbell.
