Surface Cracks Concrete Slab

[oioi727]

I have laid a concrete slab (see pictures). It was quite cool and area was covered in shade. I did not cover it as I did not have a big enough sheet to cover the area. It rained quite a bit after 4 hours and end up with standing water on the concrete.

By the time it rained the concrete had started to cure. I didn't try to move the water, as i didn't want it mixing with concrete and weakening it.


On day 3 I have noticed some light surface cracks as shown in the picture. Can somebody recommend what course of action I should take next to protect/repair. I plan on painting the concrete in a few weeks as well.

P.S. Any one know why these cracks occurred in the first place, my assumption is either the rain water or due to contraction?

Thanks,

 

[nickjb]

Assuming they aren't too deep to weaken the slab I'd scrape off and loose bits then fill with mortar. I'd give the surface a brush with a cement/SBR slurry then add some SBR to the mortar mix. Should stick very well. As for painting, has the slab been down long enough? Normally you'd leave it a month or two. You can tape a piece of polythene to it overnight and see if there is still moisture.

 

[Tigercubrider]

No expert but looks like the rain made the cement float to the top of the main concrete.
What is it that the slab is for?

If painting, you could repair it with anything suitable for the paint but check first