Pervious Concrete - InspectionNews

Bernie Caliendo · #1 (**permalink**) 08-23-2008, 10:22 AM

I'm starting to see the installation of pervious concrete for driveways and sidewalks. I have not observed their conditions in the cold northeast yet. Does anyone have experience with observing it's use in freezing conditions? I would assume it will begin to freeze and plug up.

Jerry Peck · #2 (**permalink**) 08-23-2008, 02:38 PM

Also, I can imagine that cracking will be a problem too, as that stuff has to be weaker than 'ordinary concrete'.

Ted Menelly · #3 (**permalink**) 08-23-2008, 03:04 PM

Quote:

Originally Posted by Bernie Caliendo

I'm starting to see the installation of pervious concrete for driveways and sidewalks. I have not observed their conditions in the cold northeast yet. Does anyone have experience with observing it's use in freezing conditions? I would assume it will begin to freeze and plug up.

I believe that it has a better expansion and contraction and maybe that is why they are using it and or flexibility.

David Banks · #4 (**permalink**) 08-23-2008, 08:25 PM

Pervious, Porous Concrete Pavement Engineering Properties

Seems to have good strength and freeze/thaw applications.

Jim Luttrall · #5 (**permalink**) 08-24-2008, 12:13 AM

Quote:

Note that the porosity of pervious concrete from the large voids is distinctly different from the microscopic air voids that provide protection to the paste in conventional concrete in a freeze-thaw environment. When the large open voids are saturated, complete freezing can cause severe damage in only a few cycles.

It would appear that it would depend on your weather. Heavy wetting with extreme cold could be very bad.

David Banks · #6 (**permalink**) 08-24-2008, 04:47 AM

Quote:

Originally Posted by Jim Luttrall

It would appear that it would depend on your weather. Heavy wetting with extreme cold could be very bad.

Jim. I believe they are talking about conventional concrete in your quote.

Jim Luttrall · #7 (**permalink**) 08-24-2008, 03:25 PM

Quote:

Freeze-thaw resistance of pervious concrete in the field appears to depend on the saturation level of the voids in the concrete at the time of freezing.

This is the introductory sentence of the same section.

Quote:

Note that the porosity of pervious concrete from the large voids is distinctly different from the microscopic air voids that provide protection to the paste in conventional concrete in a freeze-thaw environment. When the large open voids are saturated, complete freezing can cause severe damage in only a few cycles.

Still seems to say that saturation will damage the pervious concrete, but that pervious concrete does by design drain faster than conventional concrete. But with reference only to 10 years of historic data, I would still be looking heavily at the local weather.

Jerry Peck · #8 (**permalink**) 08-24-2008, 07:19 PM

My personal opinion is that:

- concrete is very strong in compression

- concrete is very weak in tension

- ice is very strong in expansion forces

- (okay, so those are not "my personal opinions", they are standard opinions shared by most people, including the experts)

- in cold climates water left exposed to the cold freezes

- when water freezes it exerts tremendous expansion forces which can break concrete apart (because of its low tension strength)

- in cold climates, after moisture falls (be it rain or snow), water penetrates down into gaps and cracks

- that water freezes (see above for what happens when it freezes)

Jack Feldmann · #9 (**permalink**) 08-25-2008, 05:16 AM

From the web site under FAQ's

Q: What about freeze-thaw issues?

A: Pervious concrete has been placed in freeze-thaw climates for over 15 years.
Successful applications of pervious concrete in freeze-thaw environments have
two common design features-- the cement paste is air-entrained, and the
pervious concrete is placed on 6–12 inches of drainable aggregate base (¾” or
larger clean gravel).