Deck showing cracks one day after pour? Suggestions?

[Dirk]

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!

Yikes. It sounds like a retaining wall, and I'm used to seeing treated lumber, formed concrete or concrete blocks (the latter two when supporting a concrete deck). What happens to the sand when the bags decay?

Anyway, glad to hear your PB is giving the issue some attention. I'll defer to the experts on whether that's a proper fix or not...

 

[Rich D]

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.

A good quality granular sand is as good as crushed stone for under concrete. Think of Sand as crushed rock only much much smaller. If you compact 1/2" crushed stone and then run on top of it it will move because it gets pushed to the sides. The same for sand. This is why you do not want sand under asphalt paving. When paving is hot it can be moved to the sides as well moving the sand with it. With concrete there will only be down pressure so in terms of compaction there are no issues. Of course you need to consider how much moisture will be sucked out of the concrete with whatever you place under it. This is a entirely different issue with its own subjective opinions.

Edit..

I should have said.. "A "Properly compacted" good quality granular sand is as good as crushed stone for under concrete"

You need to have correct moisture content and correct compaction process to properly compact anything.

 

[Rich D]

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

In addition any concrete will cure better - stronger when kept moist. Certainly leaving it exposed to 100 deg full sun is never a good idea (if you are looking a quality finished product )