Pervious Pavement 3

[sns777]

Can anyone give me informationo on pervious pavement? Particularly, the costs vs regular asphalt and how it holds up and any maintanence issues. The application would be for commercial parking lots and/or driveways. The reason to use it would be to increase stormwater infiltration.

 

[GTB]

Where are you using it (Area of the Country?)? Make sure you have very good drainage below the asphalt. Pervious pavement is a good base material for a pavement section but is usally topped with a surface course, it is usualy not left exposed.

 

[Focht3]

This may be a very bad idea if the pavement will experience even a very few heavy wheel loads and you have a clay subgrade. And it's a REALLY bad idea if the subgrade is expansive clay -

Talk to your geotechnical engineer about this.



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See faq158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"

 

[fndn]

Pervious concrete is a great way to hold some runoff on site but works mostly with sand and non plastic silt subgrade. The mis has no paste and is composed of larger to medium size aggregates. The last one I was involved with, I calculated the Q=kia and used the area of the parking lot to come up with a units of nearly 20 gal/sq. ft per day. If you're not comfortable with your assumed permeability k, then ask a soils lab to run a constant head permeability test. One item to keep in mind is that the ready mix producers say a modulus of rapture is 600 psi, but I suspect it is closer to 400 psi. We ended up requiring 6" of pervious concrete over 6" of 3/4" aggregates(Class II) over a subgrade compacted to 95%. This was for a commercial parking lot with an assumed traffic index of 5.5 and in a warm climate setting.

A Member of

http://www.civilvillage.com

 

[LCruiser]

We have a situation in which a pervious Superpave lift was placed over an impervious Superpave lift, then capped with OGFC. Now FHWA is concerned with the durability of the section during freeze-thaw cycles. Has anyone actually seen any failures due to this?

 

[Ron]

Freeze-thaw can be a problem with any OGFC. When you put essentially the same thing (pervious Superpave lift) you are making the opportunity for water accumulation even greater, thus increasing the freeze-thaw potential.

Unless the pervious Superpave lift has completely open lateral drainage, I'd be concerned as well.

 

[LCruiser]

The OGFC is an impervious mix. The major problem, as I see it, is that the median and shoulders didn't get the OGFC cap. The shoulders thing isn't a problem unless it's in a super, and I'm not sure I see the in situ moisture when capped to be much of a problem either - I'm thinking the problem is the ongoing addition of moisture combined with freeze thaw.

That's why I was wondering if anyone had actually seen a problem with Superpave in a situation like this.