Repairs of parking garage floor and topping
Repairs of parking garage floor and topping
(OP)
I am designing a repair for a 60 year old parking garage floor waffle slab. The floor has a 1" thick bonded concrete topping on it. The entire existing topping will be remove as part of the repair.
If the repair concrete is placed monolithically with the topping pour, the advantage is that there will be greater structural depth at the repair areas, but I am wondering if the shrinkage of the topping may create a horizontal force that could pull on the deeper concrete at the structural repair areas and cause debonding of those structurally critical areas. If the floor is 100 feet long, then the extremity of the topping will move about 0.2" based on a shrinkage strain of about 350 microstrain and assuming that the mid-length is at zero movement, so repairs near the extremities of the floor will have a significant pull on them. The topping will crack due to its mechanical anchorage by the deeper repair areas, but that is not so critical because it is going to all be covered by a waterproofing membrane and 3/4" thick mastic wearing surface.
Is it better to place the repair areas separately from the topping? In that case I would make the top of the repair areas at the same elevation as the surrounding topping.
If the repair concrete is placed monolithically with the topping pour, the advantage is that there will be greater structural depth at the repair areas, but I am wondering if the shrinkage of the topping may create a horizontal force that could pull on the deeper concrete at the structural repair areas and cause debonding of those structurally critical areas. If the floor is 100 feet long, then the extremity of the topping will move about 0.2" based on a shrinkage strain of about 350 microstrain and assuming that the mid-length is at zero movement, so repairs near the extremities of the floor will have a significant pull on them. The topping will crack due to its mechanical anchorage by the deeper repair areas, but that is not so critical because it is going to all be covered by a waterproofing membrane and 3/4" thick mastic wearing surface.
Is it better to place the repair areas separately from the topping? In that case I would make the top of the repair areas at the same elevation as the surrounding topping.






RE: Repairs of parking garage floor and topping
RE: Repairs of parking garage floor and topping
RE: Repairs of parking garage floor and topping
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Repairs of parking garage floor and topping
RE: Repairs of parking garage floor and topping
RE: Repairs of parking garage floor and topping
RE: Repairs of parking garage floor and topping
On NYSDOT bridge deck reconstruction projects we have two options for placement method.
A. Method 1 - Separate Placement. Place Class D slab reconstruction concrete and Class E
overlay concrete separately.
B. Method 2 - Integral Placement (Optional). When 100% of the top mat of bar reinforcement
is exposed or when all of the following conditions are satisfied, Class E overlay concrete and Class E
slab reconstruction concrete may be placed in a single lift.
1. The area of the exposed top mat of bar reinforcement is 5% or less of the placement area, per span.
2. No individual area of the exposed top mat of bar reinforcement exceeds 25 sf.
3. No dimension of any area of the exposed top mat of bar reinforcement exceeds 6 feet.
Class D has a slump of 2 1/2" to 3 1/2", with mostly 3/8" aggregate - 75 to 85%
Class E has a 3 to 4" slump with mostly 1/2" aggregate, 35 to 65%
RE: Repairs of parking garage floor and topping
to bridgebuster - that is very useful information indeed, and something that I can use to back up my position that it should be separate pours. Thanks.
RE: Repairs of parking garage floor and topping
Or do they do they finish the repair area to the same elevation as the top of the future topping, and then place the topping so that it fills in between the repair area concrete which is projecting above the top of the structural slab by the thickness of the topping?
Is there any specified wait period between the time of placing the repair areas and the placing of the topping, when they are placed separately?
RE: Repairs of parking garage floor and topping
In this type of project, we do the entire bridge area. The placement methods I cited are not for localized repairs.
RE: Repairs of parking garage floor and topping
RE: Repairs of parking garage floor and topping
RE: Repairs of parking garage floor and topping