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Thread: Pervious concrete

  1. #1
    Cyburbian
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    Pervious concrete

    Pervious Concrete allows water to soak through the pavement and reduces detention requirements. Has anyone seen this used?

    My immediate concern would be water freezing in the pavement and breaking it up. But if it works, it could reduce the need for ugly detention areas.

  2. #2
    moderator in moderation Suburb Repairman's avatar
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    Quote Originally posted by savemattoon
    Pervious Concrete allows water to soak through the pavement and reduces detention requirements. Has anyone seen this used?

    My immediate concern would be water freezing in the pavement and breaking it up. But if it works, it could reduce the need for ugly detention areas.
    pervious concrete is not without its problems. When used in parking lots, you still have to find a way to filter pollutants. Also, I've found that several companies that do the stuff have VERY short warranties for their work. It would be great for improved trails and sidewalks though where you don't have to deal with the weight of cars or heavy traffic.

    "Oh, that is all well and good, but, voice or no voice, the people can always be brought to the bidding of the leaders. That is easy. All you have to do is tell them they are being attacked and denounce the pacifists for lack of patriotism and exposing the country to danger. It works the same way in any country."

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  3. #3
    Cyburbian boilerplater's avatar
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    Ford Motor Company installed thousands of s.f. of this at their new Rouge River facility..pervious asphalt, that is. I went to a lecture last year by a guy from the firm that was involved with the design. According to him, it has been holding up well. They say that since the water drains through into the stone layer below, it freezes there where it will not damage the pavement. Filtering through stone and soil removes a lot of pollutants from the water, but you still may need drainage structures depending on the soil conditions.

    We had a bike path project installed within the last year that used pervious asphaltic concrete. It will be interesting to see how it holds up.
    Adrift in a sea of beige

  4. #4
    Cyburbian Seabishop's avatar
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    Wait a minute, pervious concrete gets rid of one of our main reasons for wanting less asphalt in our developments. Now we have to be happy with seas of environmentally friendly asphalt.

  5. #5
    Cyburbian mique28's avatar
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    pervious pavement is the way to go!

    Our community has several commercial projects underway that will include the use of pervious pavements in their parking lots. After researching the use of such prodcuts in our area we actually added a stipulation promoting the use of pervious materials in parking lots to our parking code and stormwater management ordinance.
    Where I am located (Milwaukee area) there are several successful examples of the use of pervious concrete that have held up well to traffic and the freeze/thaw of the Upper Midwest for the last 5 years or so. The jury is still out on how well it would hold up over the long term, but early results are very positive. By the way,an added benefit of the pervious concrete that I noticed is that with the water being absorbed through the surface you do not have any puddling and freeze on top of the concrete/in the parking lot. It makes it much nicer to walk through such a lot on a rainy day or after a snowfall (lot less nasty brown snow)

    Also there are other options to help reduce impervious surfaces and improve stormwater absorption... including not paving. Seriously, though I have seen brick and cross hatched concrete with gravel used to good effect. I have attached a picture of one such design from Madison, WI.
    Last edited by mique28; 17 Jan 2006 at 3:19 PM.

  6. #6
    Cyburbian mallen's avatar
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    Pervious asphalt and concrete have their strenghts and weaknesses. I am more familiar with pervious asphalt.

    Suitable subgrade is very important. Where I am located, we have soils with a lot of clay content. The hardpan below does not allow for great water penetration. So essentially, once you fill up the "pool" with water (whatever depth of base you provide), you are basically back to a non-pervious situation. It works best in sandy soils.

    Secondly, proper installation is essential and a little more expensive than typical construction. I have personally seen one terrible installation that deteriorated within a few months.

    Finally, the voids slowly fill-up with debris (leaf particles, dirt, etc.) which reduces the porosity over time.

    Having said that, it does work to reduce stormwater runnoff. But it is not a life-saver.

    We have also used another product called grasspave or grasscrete which is suitable for very volume low parking areas. Basically, it allows grass to grow through a structure that can support vehicle weights without crushing the grass. It basically looks like a grass field.

  7. #7
    Forums Administrator & Gallery Moderator NHPlanner's avatar
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    Attended a Stormwater Demonstration project at the University of NH, and they're studying the pervious asphalt.

    Interesting concepts all around, especially studying LID (low impact development) techniques in the cold winter environment of NH.

    Links:

    Project Overview - http://www.unh.edu/erg/cstev/
    Site Overview - http://www.unh.edu/erg/cstev/Overview_20041012.pdf
    Cold Weather & LID - http://www.unh.edu/erg/cstev/Present...en_NAHB_04.htm
    Workshop Presentation - http://www.unh.edu/erg/cstev/Present...shop_10_04.htm
    Porous Asphalt Specs - http://www.unh.edu/erg/cstev/porous_...pec_mar_05.pdf
    "Growth is inevitable and desirable, but destruction of community character is not. The question is not whether your part of the world is going to change. The question is how." -- Edward T. McMahon, The Conservation Fund

  8. #8
    Cyburbian
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    I think it has its pros and cons, in most cases I prefer it not be used because of issues with maintenance and potential pollutants. If the issue really is coverage, why not just reduce lot coverage. If it is an aesthetic issue just bump up screening/buffer and/or landscape requirements. In places it work well but everything I've seen involving any decent amount of vehicular traffic ends up in bad shape not too long down the road. Just my 2 cents... or 2 1/2...

  9. #9

    Nah

    We don't use it here. From what I've read and seen, I think that it's usage is limited as a travelled way, if at all. Looks like they would make good rumble-strips in advance of dangerous intersections.
    We have clayey soils that tend to heave in the winter, which would also raise the fill material within the pavement, which would be plowed off in the winter, then when the ground thaws and the fill material settles back into place, it seems that there would be "holes" within the pavment from the excess material that was plowed off in the winter, needing constant maintenance. Furthermore, I think eventually grasses/weeds would tend to grow outside the wheel-track areas. This leads to all kinds of maintenance problems and horrible aesthetics. I would agree that there is always debris (salt, dirt, fluids, rubber from tires, etc.) that would be added from cars (maybe enough to fill the voids left from now plowing) and reduce its permeability. There is also a lot of prep (subgrade) work to install these for the minimal amount of additional drainage that they would add. I'm guessing it is close $ to $ for asphalt pavement installation, does anyone have that?
    If the object of these pavers is additional drainage and to be environmentally friendly, how about removing the paved driveway requirement? That would go alot further in reducing run-off stormwater added to your system, than adding these "permeable" paved areas all over.
    Who's gonna re-invent the wheel today?

  10. #10
    Cyburbian
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    I think you'll find that permeable paving tends to be less cost effective than standard paving. Where I currently work, the City requires parking spaces above the required to be of an approved pervious surface and approved by the Director. I have a problem with it. What is its purpose??? To decrease run-off??? Ok, if its that big of an issue don't allow as much lot coverage and increase FAR when possible. Is it a aesthetic issue??? Ok, then bump up landscape regs for parking lots and their perimeter along with building placement. I do believe it is much more practical to use permeable surfaces for parking stall vs driveways though. The drives will have more traffic and potentially heavy traffic which would really shorten the lifespan of the permeable paving.

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