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seacaptains 09-28-2008 06:58 AM

Sakrete and standing water
I just used Sakrete Concrete Mix - 5000 Plus to pour three footings for a small porch (4'X8') that will extend off the front of a shed (8'X10') that I'm building. I dug the holes to the frost line, put crushed stone in the bottom 2"-3", then poured Sakrete loosely on top of the stone for another 2"-3", then poured the footings into 8" Sonotubes on top of that. I finished pouring the footings at various times in the afternoon on Friday, the first one at about noon, the last one at about 3 PM. I held off on backfilling the holes because I figured the loose concrete in the bottom needed time to set. At 7 AM on Saturday it began to rain and by the early afternoon I noticed the holes had 1'-2' of water in them around the Sonotubes. So the Sakrete had some 16-19 hours to cure before the rain started. (We had covered the holes with a tarp, but the site is on a slight slope, so runoff that ran under the tarp was what caused the water in the holes.) My question: Should I be concerned about the effect of the standing water on the concrete?

Blue Jay 09-28-2008 10:12 AM

No need to worry, concrete sets due to chemical reaction not drying out.

Square Eye 09-28-2008 03:08 PM

Dams and bridges have standing water in the forms when they pour. The concrete displaces the water and some say that concrete performs better when it sets under water. So, You're fine :)

mudmixer 09-28-2008 04:33 PM

You were probably lucky it rained to provide the moisture for the dry Sakrete to start curing. Because you used 2-3" of rock in the bottom the concrete could have run into the voids and cause a minor settlement. but that would have eventually since the rock has voids that will eventually be filled.

No problem. If you used more rock, you could have bigger problems. Water does reall not hurt concrete (usless added before placement) as Square Eye said. I was a bridge inspector on jobs where we routinely poured concrete in 10 to 20' of water. - Major bridge piers for 300 - 500' spans.

inspectorD 09-28-2008 05:28 PM

The only problem you will have, is when you find out you have one in the wrong spot.
Like it was said already, you'll be fine. It's when it is freezing out and you pour concrete, you may need to worry.

mudmixer 09-28-2008 08:43 PM

If you pour concrete in unfrozen gound, you do not have too worry much about air temperatures. The important thing is the temperature of the concrete, which heats up as it hydrates.

Also, there is no magic 28 days for strength as some peole think. That only applies to lab tests for concrete mixes to measure of the right proportions were used.

seacaptains 09-29-2008 08:10 AM

Sakrete and standing water
Thanks, guys, for all the helpful and encouraging comments. I was feeling good, then I just got the following reply from Sakrete's technical rep (I had sent them an email, too, when I sent the one on this site):

"Yes, you should be concerned. That amount of water would make the concrete very weak and it would not be able to support the weight that you need it to."

??? Now I'm really confused

JoeD 09-29-2008 05:00 PM

Did you pour the concrete into the hole dry or was it mixed with water? Once mixed with water the concrete will set up in about 3-4 hours. After that no problem with water.

inspectorD 09-29-2008 07:33 PM

Don't worry about it.
The rep is probably doing damage control as always.
You are not building a bridge, or a two story addition.
The soil that surrounds the concrete does just as much, where will it go?
Never seen a pier jump out of the ground yet.;)

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