Concrete Cracking
Concrete Cracking
(OP)
There was a new building constructed (less than 2 months old) and the reinforced concrete slab has considerable surface cracking near the control joints in some instances and nearly in the middle of others.
There are no records of control testing during the construction of this bldg - nonexistent (i.e. no In-place densities on the subgrade and base materials, no documentation of the concrete testing - slump, air, W/C ratio, mix design, etc...)
What are some possible root causes that may have contributed to this type of failure?
What is a good approach in determining what actually caused this failure and what are some possible lines of resolution? (tearing the whole building down and starting over - not really an option.
There are no records of control testing during the construction of this bldg - nonexistent (i.e. no In-place densities on the subgrade and base materials, no documentation of the concrete testing - slump, air, W/C ratio, mix design, etc...)
What are some possible root causes that may have contributed to this type of failure?
What is a good approach in determining what actually caused this failure and what are some possible lines of resolution? (tearing the whole building down and starting over - not really an option.





RE: Concrete Cracking
surface.
http://www.cement.org/tech/faq_cracking.asp
Can you post a picture?
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RE: Concrete Cracking
Your other crack photo is more indicative of joints too far apart in both directions. This was likely a crack occurring in a slab panel interior to the building.
Although you have a finish on the slab and that might be obscuring my interpretation, it looks like there might have been excessive bleed water in the concrete. This is indicated by two things...first, some fine map cracking at the surface and secondly, the appearance of dark reflections of the coarse aggregate just below the surface. I think I'm seeing both in your photos, but could be wrong without additional photos to prove.
As hokie66 noted, there are numerous reasons for such cracks to occur, but almost all of them are related to poor mix control and placement by the contractor.
RE: Concrete Cracking
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Kieran
RE: Concrete Cracking
I appreciate everybody's input. If any recommendations on how to resolve/alleviate this problem could be suggested - also greatly appreciated.
RE: Concrete Cracking
Make the sawcuts to a depth of 50 percent of the slab thickness. This step is important as the slab will continue to shrink.
Epoxy inject all "random" cracks. Then apply a pigmented epoxy floor finish for all exposed areas.
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Any particular epoxy (recommended manufacturer)?
RE: Concrete Cracking
http://ww
RE: Concrete Cracking
After you're done with the crack injection, coat the entire area with an epoxy surfacing to hide the repairs. You might also need to broadcast sand into the top layer of coating to provide slip resistance if the floor has forklift or foot traffic on it.