Spalling Concrete
Spalling Concrete
(OP)
I have been asked to give a possible reason and repair for the concrete spalling in the attached photos. I have asked for the concrete reports, but do not have them yet. I am looking for some general thoughts on what might be going on here. This job is located in the north, and was winter construction. My first thought was freezing issues, or under consolidation or delamination. Thanks.






RE: Spalling Concrete
RE: Spalling Concrete
RE: Spalling Concrete
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RE: Spalling Concrete
RE: Spalling Concrete
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Spalling Concrete
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RE: Spalling Concrete
As for the repair. assuming you don't need the concrete strength for uplift you can probably just use a SIKA spall repair mortar mix. For shear you can look at each side working to transfer all the load, not as a group of embed four anchor bolts. if that doesn't work then you need to attach sleeves to the beam to (say angle with leg down on one side and plate on other both pressed against concrete wall) then through bolt the two sleeves tying it to the wall.
RE: Spalling Concrete
RE: Spalling Concrete
For the beams, if axial loads do not need to be transferred, I like to bolt the beam to the embed plate with threaded studs. This eliminates field welding and gives you an opportunity to include long slotted holes to, hopefully, allow thermal stresses to dissipate through slip. If no axial loads need to be transferred, your beam connections are probably just simple bearing connections and the studs behind the spalling can be sacrificed. Just clean it up with SIKA as you've suggested.
For the connection between the deck and the the top of the wall, you can check to see if the embeds will transfer the deck shear using only the studs that have not spalled. If there isn't enough capacity, you could add a deck support angle to the face of the wall. Depending on whether or not your roofing is in place, you may have to connect to the deck from the underside. Either way, I'd ignore the capacity of the studs behind the spalling unless you're willing to chip out the concrete behind the stud and create a repair that is more than a cosmetic fix.
For all of the photos, it wouldn't have hurt to have had some wall rebar outboard of the studs. Maybe the walls are 8" with only one central mat, I'm not sure.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Spalling Concrete
2nd photo is that of exposed studs or anchors for deck bearing. Normally, we would like a layer of rebar between anchors and inside face of wall (none is evident in this photo).
3rd photo shows beam bearing plate hanging over edge of wall. I would suspect beam rotation putting excessive stress on the face of the concrete which would cause spalling. Note that there is, once again, no inside face wall reinforcement outside of the anchors.
RE: Spalling Concrete
An alternate connection might be a vertical embed plate with anchors that beam clip angles can be welded to. Clip angles should have bolted slotted connections to the beam for field adjustment and reduction of eccentricity due to beam rotation.