Deck showing cracks one day after pour? Suggestions?

[CMorrow]

Hi, folks. Deck was poured yesterday and is already showing cracks. Took some pics last night and again this am. Is this a sign of trouble or could it be fixed by cutting a new joint or two early this upcoming week? In terms of prep for pour, it was decent: rebar was raised in most places a few inches off ground, a fair amount of sand was dumped and sand bags stacked. Tamping was decent. What I've learned from this build is the workers are really only going to give 80%. I don't like to concede, but my options have been to fight EVERYTHING or yield in places. With the cracks here I'm wondering specifically--
1. Might a new joint or two alleviate the stress and prevent further cracking, or is this a very troubling sign?
2. If new joints are cut, will an epoxy cover up these cracks fairly welll? The deck will also receive two rounds of kool kote.
3. Is requesting these slabs get busted up and repoured the way to go?
Trying to anticipate my conversation with PB tomorrow.
Thank you!

 

[santacruzpool]

Concrete cracks - period - but it can be managed by using control joints with tooled grooves while floating the concrete and/or saw cuts after the concrete has hardened. The control joints are used to coax the concrete to crack in a known location along the control joint (and out of sight). Even with good control joints random cracks can, and often will, still happen.

Hopefully some others will be able to provide further help regarding what your coating will cover and other options etc...

 

[CMorrow]

Thank you. That's helpful. Here are some additional pics.

 

[Txjole]

I’ve done some concrete work (young and dumb). How hot was it when they poured? Looks likes a “blow up”, top layer cured super fast and lower swelled. But yes, concrete WILL crack

 

[CMorrow]

Yes, was very hot -- 100 easy. So your thoughts are that it might need to be redone completely?

 

[Txjole]

They should have water blanketed it. Control the surface temp. Called a run away. They had no control of the mud (if u want to talk “finisher” talk).

 

[CMorrow]

Ok. Thanks. In your opinion, is there a quick fix, i.e. cut some new joints, or should these slabs be completely redone?

 

[PoolGate]

I would be very annoyed. I suspect this was not done properly.

 

[Pv2]

Husband is a masonry contractor (doesn't like concrete work, though LOL) but he says they can score it a couple more times and even cut out the crack and just repour that piece. If you are getting kool kote it is probably fine to just score it.

 

[Dirk]

What do you mean by "a fair amount of sand was dumped and sand bags stacked." I was schooled here when I was writing about sand under a concrete slab, as in: there is not supposed to be. Because it cannot be properly tamped. I believe it's supposed to be crushed rock under your deck.

But previous posters are on to something, i think. This looks to be a curing issue, not so much a stress crack.

Can Kool Kote mask the cracks? I wouldn't know. But if a deck is not supposed to be poured over sand, and yours was, maybe you'll have even more trouble down the road, and this is just the first of it...

Where are our concrete guys? They'll know.

 

[scdaren]

Some concrete contractors use sand. I know ours did, and they are a very experienced and reputable concrete contractor. Perhaps it depends on the soil type, and requires a certain grade of sand. We have cracks, but only where they scored.

Or contractor guaranteed we would get cracks, he joked it was his only guarantee. But I think getting them so quickly and not where they are expected to be is a sign that something is very wrong.

 

[djust]

When I poured my shop floor the concrete guy told me I got three guarantees, that it would turn hard, it would turn white and it would crack. Have to admit it didn't seem humerous at the time but in the end after 12 years it is just now starting to hairline crack above the footings. I have a few hundred feed of concrete decking coming in a couple weeks with my pool and it does concern me a little, at least the temps should start coming down here in Oklahoma pretty soon I hope.
Need to keep water on it for a few days after its poured to help it slow down the curing process. There was no sand under my shop floor but there is on my sidewalks, driveway and will be under the new pool decking also.

 

[Dirk]

There's sand under my sidewalks, which is what I was sharing in another thread, when someone pointed out that wasn't right. I googled it, but there seems to be some mixed thoughts on the subject. Probably comes down to use. Sand OK for some applications and locations, not for others? It was just meant as something for the OP to be aware of and consider...

 

[bmoreswim]

Ours had numerous cracks in it the day after they poured it. It went from cloudy and 70’s to full sun and 80’s during the pour. They said the mix was too dry for the unexpected sun.

I’m a realist. The fix would have been worse than the problem (which would have likely occurred sometime anyway). It was for 1600 S.F. so not a small job.

 

[CMorrow]

Thanks, folks. That's all useful information. PB coming out tomorrow to take a look. Says that if a dime can stand upright in the crack, then that's a serious one to deal with, and if no dime will fit, then it's less serious. Also believes from the pics I sent him that these are surface cracks. At any rate, I tried the dime test today and there wasn't enough space for it, but it was close in places. That said, I want to give the PB the benefit of the doubt. They're a reputable company and so far have been attentive to my concerns, especially since many of the subs (as I mentioned above) strike me as doing about 80% of a good job. So far the PB has called them back to do right what they should've done right the first time. So I want to see what his solution will be to this one. As everyone's been saying, I know the concrete will crack -- in time -- just was hoping to get a few years in before that happened. Will be interested to hear PB's take. The way I'm seeing it at the moment, I'm hoping for a few more expansion joints to be cut and repairs made to the existing cracks. Then Kool Kote and cross fingers. I'm hopeful that'll do the trick -- until it eventually cracks for good. But if anyone has another suggestion I should bring to PB's attention, please share. The more informed I can be, the better.

And as far as the sand goes, workers dumped sand and rock over existing soil in most places, then stacked sand bags on the edges of the deck that were higher than a foot or so. I've been told by neighbors that that's the method here (central TX), so I have to trust that it is.

I'll keep y'all posted after I hear PB's take tomorrow.

 

[Dirk]

And as far as the sand goes, workers dumped sand and rock over existing soil in most places, then stacked sand bags on the edges of the deck that were higher than a foot or so. I've been told by neighbors that that's the method here (central TX), so I have to trust that it is.

I'm trying to picture that. Is part of your deck poured over bags of sand, stacked on top of each other, still in the paper bags in which they are sold? Or when you say bags is it like sacks of sand one would stack up to ward off rising water? Like that? Got a picture of that?

Good luck tomorrow!

 

[jimmythegreek]

That's the slab shooting off cause of the temps seen it many times. They should have added chemicals in the mix whem ordered to help and used a better quality mix. We make final mix decision when we make the call for the truck to head over to the job

 

[delrayser]

Let us know what your PB says. I had almost the same experience with my Austin build this summer, they poured in 100+ heat and we had cracks in the deck within a week. PB told me they were surface cracks and gave me the same "dime test" line. I know all concrete will crack, just wasn't expecting it so fast. But I will say this, it bothered me a ton until we actually got to fill day, now I'm learning to take it in stride and enjoy the water.

And as far as the sand goes, workers dumped sand and rock over existing soil in most places, then stacked sand bags on the edges of the deck that were higher than a foot or so. I've been told by neighbors that that's the method here (central TX), so I have to trust that it is.

That's almost exactly how they built our deck. Sand bags on the vertical edges, crushed rock/gravel inside that, rebar on top. Must be the Texas Standard.

 

[sktn77a]

Also believes from the pics I sent him that these are surface cracks.

There's no such thing as a surface crack (it's called crazing, not cracking, and your picture is a good old-fashioned crack)! Cutting the concrete may help to slow the crack opening up (if you don't get freezing weather, that helps, too). Seeing you are covering it with Kool Kote, you can try.

 

[CMorrow]

Quick update: workers came and opened cracks a bit, them filled them with more cement. They also cut two additional joints. That said, I'm going to request two more joints be cut. For the most part, the fill did the trick, except in a few places where a much thinner -- albeit still visible -- crack has reemerged. Meeting with PB upcoming week to discuss. At this point, I don't expect anything like busting up the concrete and repouring. However, I need to know they are doing / will do all they reasonably can to prevent these cracks from opening again too soon.

- - - Updated - - -

Yes, Dirk. Sand bags like those used to stop rising water. Then crushed stone and sand mixture duped all around. As delrayser says, must be the Texas Standard. Now is that a high quality standard or a low quality standard.....? Trying not to answer that one!