Wet Curing concrete

[USAFpj]

I realize how important it is to maintain moisture within/on a fresh slab. My question is that the 12ft tall overhead doors are open, and direct sunlight is able to beam into the shop, and onto the slab.

Should the garage doors be closed to about half way down to allow moisture to evaporate and escape, but not allow sunlight in?

 

[the GOAT]

Yes, keep the direct sun off if you can.

 

[matt_i]

As long as you continue to flood the surface and not let it dry out I don't see an issue. Think of a slab cured in the wide open.

There are also curing sealers you can apply and forget about, but those have to be bought ahead of time and ready as soon as one can walk on it with sock feet without damage.

 

[Cyberbear]

I've always used the curing sealer with very good results, along with plenty of steel, not mesh, and have never seen any cracks other than some surface checking over time. It also helps to have a good rich mix for the concrete which relies on the proper amount of cement for each batch. My last slab was 36 yards, 21 years ago and still no cracks.

 

[USAFpj]

Of course, I'm worried about keeping this freshly poured slab hydrated, and now it's raining. With extreme thunderstorm warnings for our area.

I'm appreciative of what I have, but man, I've had a heck of a time with weather and this shop build... Building a shop supposed to be fun? I can't say that I believe that.

 

[pcmeiners]

Sound like great weather for curing the slab.
Sunshine does not matter if the slab is kept WET, sunshine is an issue if it dries the concrete. Hell of a lot easier to maintain the wet condition without the sun directly on it.

"to allow moisture to evaporate and escape".
NO...the curing process needs the moisture in the cement which is needed in the hydrating process. The more moisture (in the air)/water you have on the slab the better the cure.

 

[USAFpj]

Got it. Now the inside of our recently built house is leaking. Ha! When it rains, it pours!

 

[Lassen Forge]

If it gets hot again... Cover it with heavy visqueen with taped seams. We cured concrete out in the open on a hot sunny day like that, no problem. The sun won't hurt as long as the concrete stays damp.

 

[wssix99]

Should the garage doors be closed to about half way down to allow moisture to evaporate and escape, but not allow sunlight in?

You should shut your doors to cut down on the wind effect.

If you look at this tool, you'll see that you do have a worry this week about evaporation: https://plasticcracks.siue.edu/index.php?unit=Standard&zip=29601

If you "modify conditions" to "indoor", which I understand models no blowing air over the slab then that really cuts down on the evaporation of water from the slab.

Cool tool...

 

[btdobie]

I have heard of people putting flattened cardboard boxes over the concrete and spraying them with water till soaked. It helps keep up the moisture longer especially in direct sunlight.

 

[Falcon67]

I watered mine for two days and when dry the surface was 130F plus after that. The day we poured was around 110F air temp. You may be overthinking it a bit, especially if you are overcast for a while.

 

[larry4406]

I ran garden soaker hoses on low for 2-3 days on a 28x56' slab that was 4-5" thick. Slab surface constantly wet. I still got minor cracks. This was in 80-90F weather.

 

[Jeepster04]

Concrete can also get too hot, which can cause all sorts of random cracking on the top surface of the concrete. If its a hot 90F day and you cover it in plastic then its going to get crazy hot. Concrete is a chemical reaction, which produces heat.

Closing the doors altogether and keeping it wet would be the optimal conditions.

If its in direct sunlight the curing seal would probably be the best route. Not much else you can do to keep it cool. Maybe wet burlap, thats what we use on bridges to help the concrete cure but they are also poured at night.

When they were pouring the hoover dam they actually had pipes in the concrete with chilled water flowing through them to keep the concrete from getting too hot.

 

[USAFpj]

Thanks. The overhead doors are closed, and because I'm not there- the wife/kids use a garden hose and spray the slab down about 3x times a day. Not exactly able to flood it, but do what we can for about 7 days, anyway.

 

[R. Deschain]

Take a look at the the Ashford Formula to seal the slab as well. I have seen it used at Boeing with fantastic results and I will use it an any slab I pour from now on.

 

[machsnell]

The tough specs on jobs call for burlap and plastic over it. Wet it down and do twice a day.

If you set it down well and cover you are miles ahead of 99 percent of other slabs....and equal to mine


Sent from my SM-G900V using Tapatalk

 

[theoldwizard1]

As long as you continue to flood the surface and not let it dry out I don't see an issue.

This is very old school. You don't see it done much any more. Slow cure is the best.

 

[Chaznsc]

You can get it too wet, end up with surface spawling.

 

[joes169]

You can get it too wet, end up with surface spawling.

Please explain, I've never heard of it............