Bond Breaker When Placing Concrete over Asphalt?
Bond Breaker When Placing Concrete over Asphalt?
(OP)
Hello everyone,
I am reconstructing an airport pavement and the surface part of the section is 16" of PCC wich is being placed on top of 4" AC. Normally I would not see a problem with this but I have heard rumours of a law suit at the airport in Portland, OR. I believe that design involved placing concrete over asphalt as well (although I am not sure) and excessive cracking of the concrete was deemed to be the result of the concrete bonding to the underlying asphalt layer. Does anyone know more about this case?
Can anyone confirm similar experiences where bonding between PCC & AC have been the cause for excessive cracking in the PCC? If that is the case, what would be a good fix for the problem? (smoother & more dense AC mix?)
I know that the FAA previously have not allowed us to have an aggregate "interlayer" (such as sand) sandwiched between two pavement layers.
Any comments or experiences are appreciated.
I am reconstructing an airport pavement and the surface part of the section is 16" of PCC wich is being placed on top of 4" AC. Normally I would not see a problem with this but I have heard rumours of a law suit at the airport in Portland, OR. I believe that design involved placing concrete over asphalt as well (although I am not sure) and excessive cracking of the concrete was deemed to be the result of the concrete bonding to the underlying asphalt layer. Does anyone know more about this case?
Can anyone confirm similar experiences where bonding between PCC & AC have been the cause for excessive cracking in the PCC? If that is the case, what would be a good fix for the problem? (smoother & more dense AC mix?)
I know that the FAA previously have not allowed us to have an aggregate "interlayer" (such as sand) sandwiched between two pavement layers.
Any comments or experiences are appreciated.





RE: Bond Breaker When Placing Concrete over Asphalt?
There are several ways you can handle this. One is to use a SofCut saw and space your control joints closer than usual, with sawing taking place very soon after placement, and the depth of the joint deeper than usual to force early cracking in the joint.
Another way (and this is preferable to others) is to break up the asphalt using a reclaimer, which will break the asphalt layer into smaller aggregate-size pieces and in the process mix it with the underlying soil to create a very good subbase for the concrete pavement. This process is relatively inexpensive (a few dollars per square yard to break and mix). You can then place the concrete as anticipated with normal joint spacing.
RE: Bond Breaker When Placing Concrete over Asphalt?
RE: Bond Breaker When Placing Concrete over Asphalt?
I am at a loss why you have used asphalt followed by concrete, perhaps you should post this question on the civils page as concrete is only one aspect of this issue.
RE: Bond Breaker When Placing Concrete over Asphalt?
RE: Bond Breaker When Placing Concrete over Asphalt?
Gregory A. Johnson, P.E.
www.midwesttestinglabs.com