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Re: Cracking in Concrete Slabs on Grade

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This may be associated with the shear "key" in your joint.  If your slab
section looks like this:


the crack probably propogated above the key.

--- Domenic DeAngelo <domdean(--nospam--at)> wrote:
> I was wondering if I might get some input to a"problem" which has occurred
> recently. I designed a 6" concrete slab on grade with control joints at
> column locations and mid-bay locations (the column spacing was 25' x 25').
> Two days after the slab was poured and control joints cut, the slab cracked
> within 1/2" of the control joint. It started at the diamond shaped isolation
> joint continued for about 10 feet angled away to approximately 3" from the
> control joint for a distance of about 2 feet and then angled back in. On the
> other side of the column the crack followed the expansion joint. This
> happened approximately one month ago and no further cracking in the slab
> (other than where it was supposed to) has occurred. Needless to say, the
> owner (it is a moving van storage facility) is not happy since the area will
> be subjected to forklift traffic. Can anyone explain why this happened and
> if there is another way to repair the area in question besides non-shrink
> elastic grout?
> Thanks in advance,
> Domenic DeAngelo P.E.

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