***new Concrete Floor Shifting**

[groove grabber]

Help, I had a 30x48 slab, 5in thick poured approx. 3 months ago. Then approx 2 months ago I cut control joints every 10 ft by 12 ft, 1 inch deep. Previous to the cutting their were no cracks of any kind. Just the other day I went to check on it and noticed that on one end of the building(the end where I used 16 in of fill, but I did compact very good) along the cut line had opened up from a 1/4 wide cut to almost 1/2 wide!! The crack was also visible down inside the cut and was almost a 1/4 also. What do I do? Has it settled there and will probably stay close to that or should I expect it to widen. Right now, I'm not worried about it as I plan to fill anyways for epoxy but I dont want it to grow much more. I also have developed some small hairline cracks that sem to run up to about 8-10 ft long and then just stop. Should I grind them and patch before epoxy or not?

 

[menz300]

Well one thing you can always tell people about concrete. It will crack. I am not sure where you are from but I would say it is not even close to being done settling. I don't know if you have freeze and thaw cycles or not but I think it will still settle and not sure how much more it might crack.

 

['the epoxy floor guy']

Is the slab poured with 'frost footings'???

If so I would just mark it up to one of the two guarantees of concrete:

#1 it will get hard #2 it will crack

We have an epoxy control joint filler that stays flexible (like an eraser) and will allow for the joint to move 'some' and still maintain a seal.

IMHO I would wait and keep an Eye on it for a few more months before I would rush to put a coating on it.

If I was in a freeze/thaw climate of the northern USA I would try to wait until spring to see how the crack behaves.

Hope this helps.