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View Full Version : How well does pervious concrete weather?



Stephen Tashiro
03-21-2013, 11:08 AM
According to the web, "pervious concrete" is concrete made with only coarse aggregate and cement. It looks like a fossilized rice krispy treat. Its virtue as a paving is that water passes through it.

How well does pervious concrete weather? Do small pieces of aggregate continually break off? In a dusty environment, do the pores of the paving fill up with dirt, making the surface impervious to water?

Shawn Pixley
03-21-2013, 12:09 PM
I really don't know anything about "pervious" concrete. I suspect though it would weather terribly in any place with a freeze / thaw cycle. Water would get trapped in a crevise and freeze fracturing the concrete. If it weathered well, it would be highly desireable in urban areas to minimize runoff.

David Helm
03-21-2013, 12:47 PM
I only know of one situation, a driveway, that has been in place for 6 years. Aside from growing some moss like other concrete in this area, it is still in excellent condition. New development in our watershed is required to limit the amount of impervious structure so pervious concrete can be an important factor in building flatware.

Lee Schierer
03-21-2013, 7:50 PM
I can't speak about porous concrete, but a local "Green" building has their parking lot paved with a porous blacktop and it has held up well for at least 8 years so far in NW PA where we see lots of snow and freeze/thaw cycles. The rain water runs right through the pavement.

Curt Harms
03-22-2013, 8:25 AM
I can't speak about porous concrete, but a local "Green" building has their parking lot paved with a porous blacktop and it has held up well for at least 8 years so far in NW PA where we see lots of snow and freeze/thaw cycles. The rain water runs right through the pavement.

I expect to see more of it in the S.E. corner of the Commonwealth as well. Stormwater management was a hot topic until development went in the hopper post 2008. My understanding is that pervious surfaces, either asphalt or concrete cost more to put down but not a lot more to maintain. Don't know how true that is. If pervious surfaces reduce the need to stormwater retention basins that would help to offset the additional cost.

Bob Banka
03-22-2013, 11:25 AM
According to the web, "pervious concrete" is concrete made with only coarse aggregate and cement. It looks like a fossilized rice krispy treat. Its virtue as a paving is that water passes through it.

How well does pervious concrete weather? Do small pieces of aggregate continually break off? In a dusty environment, do the pores of the paving fill up with dirt, making the surface impervious to water?


Stephen, Pervious concrete has been used in the US for almost 40 years now. Ten years ago the industry started wondering what would happen outside of Florida in harsh winter environments. We found a parking lot in Burlington, Vermont where the frost level reached 4 feet and we built a pervious parking lot with three different thicknesses of a stone recharge bed. What we learned is that at least 12" of stone which has 40% voids is good enough to make pervious work in harsh winters. Every site is different as are local ordinances therefore there is no standard but as long as the water can pass through the pervious and not stay in it and freeze, pervious works great. A bigger concern is bad mix designs that use too much cement or too large of a stone. For more info feel free to visit our website, www.perviousconsulting.com or email me at bobbanka@gmail.com with other questions.

Lee Schierer
03-22-2013, 12:29 PM
Since the storm water penetrates the paving and goes into the ground, there is less or no need for for water retention basins.

Curt Harms
03-23-2013, 8:08 AM
Since the storm water penetrates the paving and goes into the ground, there is less or no need for for water retention basins.

Right, and there's another benefit to pervious paving. At least around here where water can be slow to soak into the ground and builders all try to do perc tests during a drought. Zoning variances and building permits can require a certain % of a site's surface area be not paved over i.e. not impervious for storm water management and aquafier recharge. Not having to count roads, parking lots, sidewalks etc. as impervious can help a lot.