Garage Concrete floor crack 12 hours after pour.

[Cavester]

I'm going demented with this build, never again.

Garage floor was not level so builder dug out a section to relay and make level, so that the garage door would sit flush.

That was poured at about 12 pm yesterday afternoon. Steel mesh was inserted also and it's about 150 deep slab.

I have looked through morning and there is a few long cracks. Is this anything to worry about or should I move on? Just a shame when it's brand new and not even close to dry yet. Anything can be done about it?

Pics attached...

 

[ivixor]

It's a garage floor, not the footings for a suspension bridge! It's a barely visible hairline crack, totally normal when concrete dries. Inevitable if there are no relief joints.

Don't stress about such irrelevant things, you'll be much happier.

 

[pete50]

If it's cracked it's cracked. The price these "builders" ask for laying a bit of concrete I would want it perfect. What about the swirl marks? Surely a "competent" slab layer can lay a smooth slab. Sorry I wouldn't accept that.

 

[JohnD]

in your pic, the sun is shining on it, which will dry it out too fast. Sprinkle it with a watering can and lay some plastic or cardboard on it. If you can keep it wet for two weeks, it will be harder, stronger and make less dust.

 

[Cavester]

Swirl marks are more prominent because it's not dry yet. I'm not worried about those, it's a garage. My main concern is to whether the cracks are an issue 12 hours after pour and what, if anything, can be done with them.

 

[JohnD]

Most likely it's just shrinkage. It will pull away from the forms or adjacent concrete as it cures and dries out. If the mix was excessively wet it will shrink more. When the concrete is laid in bays or against forms, the cracks are in nice straight lines and look better. If you have cracks in the middle of a (fairly small) slab, that's not normal.

You mention steel reinforcement so I expect the strength will be adequate.

The finish does look rather shoddy. It could have been lightly trowelled after initial set for a flat smooth look (but too much working brings a cement cream to the surface, and spoils it)

 

[^woody^]

Cover it with polythene for a week.

Trowel or brush that crap surface first though

 

[Cavester]

I suspect it will be too dry to do anything about the surface now. But will cover it as suggested.

The builders are proper shoddy and just want them finished and gone now!

 

[bobasd]

sloppy mix - to much water
an very poor finishin mostly becaus they went at it to soon.
the edge against the threshold board should have been rounded over,its to sharp.

the pour is still green so it can be rubbed with a stone for a more decent finish.
whats the join with the old floor like? hopfuly they cut a line not a smash up join?
was a new membrane tied into any older membrane?