I inspected a home yesterday. Foundation was slab. Some of the concrete was what I would call spalling. It was delaminating from itself in about 1"-thick pieces. At one corner it was still in place, but I could see that about a 4 foot piece of it was loose (again about a one to one and a half inch thick piece.)
What causes this and how much of a problem is it?
Thanks in advance for any help.
How old of a home? Do you have any pictures?
It could be anything from too much water used in the mix, fillers used in the mix, wrong mix, or when it was being finished it was drying too fast and it was “burned” with the trowel or machine.
What did the spalled surface look like? flat stones? round stones? little black specks?
To spall an inch deep, I would have to go with the wrong sack mix, fillers used in the mix, or way too much water.
IMHO
Steve
MM,
Many reasons for this to happen. See previous nachi and other sites.
Can be a big enough problem to advise consulting an SE in some instances.
But you knew that.
http://www.nachi.org/bbsystem/viewtopic.php?t=15035
http://www.foundationperformance.org/Projects/FPA-SC-03-0-Dec00.pdf
Mike, sometimes when you get peices that big coming off it’s not actually concrete that’s delaminating but a parge coat applied to cover concrete surface deterioration. The parge coat can be up to about an inch thick and sometimes does not bond all that well to the original concrete, so over time it will begin coming loose, sometimes in large sections.
Could be an overlay coming loose or it could be delamination of the structural slab at a reinforcement level. Try this site for more info …
Good links on that site Robert, thanks.