Flaking Concrete Slab - Why?
Flaking Concrete Slab - Why?
(OP)
We just had a concrete patio poured at our church. Right after we were allowed to walk on the patio we noticed some dime-sized (circumference and thickness) depressions where it appeared as though a layer of the top had flaked off. Those areas have now grown in size but not in depth. It truly is that the top layer is "flaking" off. What caused this and what should we do to have it rectified? Does our contractor need to cutout and repour? We are not getting many straight answers...>Church Patio.





RE: Flaking Concrete Slab - Why?
If the contractor didn't wait for the bleed water, but went ahead and trowelled right away, he was essentially sealing off the top surface with a thin, tightly condensed layer (dime size thickness?) of cement. The bleed water rises, and then cannot work through the top layer, remaining in place, just below the surface. After hardening and the water eventually disappearing, you have a thin layer of concrete surface, with possible voids or weak layers directly below.
Thus, you get the flaking off of the hard surface.
The fix? You've got a poor surface from which to work....with the weaker concrete and all.. I would suggest having the contractor do either one of two things (others in this forum can also chime in!)
1. Remove the slab and start over.
2. Have the contractor grind down the top 3/4" of surface, leaving it roughened. Apply a bonding agent to it, and apply a patching material or other concrete overlay. Not knowing where you reside its difficult to come up with an exact solution. If this slab is of considerable area, and expense, you might want to bring in a local engineer to study and recommend a solution.
Option 2 above will not give you, really, what you paid for as the "patch" will eventually work loose if you have freeze/thaw action and/or you have significant wheel loads on it (patio tractor
RE: Flaking Concrete Slab - Why?
Carl Bauer
www.bauerconsultbotswana.com
RE: Flaking Concrete Slab - Why?
Good Luck!!