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AR15.COM
5/22/2017 8:35:45 PM EDT
So I'm putting new supports (which had none) under my cantilevered deck and have a question about the footings.

I'm not what you would call a concrete expert so here goes.

I'm going 36" down and using 8" form tubes.  It's particularly rainy where I am right now.  

Aside from difficulties in digging out almost 4 feet of wet clay, are there issues with water fill and water standing compromising the pour?  I would cover the forms after pouring.
5/22/2017 8:38:25 PM EDT
[#1]
Concrete will cure under water. I'm not shure how well it will cure, good or bad, but it will get hard even under water.
5/22/2017 8:40:48 PM EDT
[#2]
You have two separate issues here.

First off is the possibility that the soil that the concrete will bear on will become saturated.  Saturated soil doesn't do very well at holding things up.  If you get water in the hole, pump it out and let it dry out a bit before pouring.

Second of all is getting water IN the concrete mix while it is fresh.

After the concrete has set a bit, it'll handle water nicely.  Some curing is done by "ponding" water on the surface, but more frequently burlap is used and kept moist with soaker hoses.  You don't want to get the surface too wet too early before it sets as that can damage the top surface.  Probably not absolutely critical for your application, but it's a good practice to allow it to set a bit before flooding it.

So, if you can keep the soil below dry, and keep excess water out of the mix, it'll be fine.
5/22/2017 8:44:41 PM EDT
[#3]
Quote History
Quoted:
Concrete will cure under water. I'm not shure how well it will cure, good or bad, but it will get hard even under water.
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Mix with antifreeze?
5/22/2017 8:47:46 PM EDT
[#4]
Quote History
Quoted:
You have two separate issues here.

First off is the possibility that the soil that the concrete will bear on will become saturated.  Saturated soil doesn't do very well at holding things up.  If you get water in the hole, pump it out and let it dry out a bit before pouring.

Second of all is getting water IN the concrete mix while it is fresh.

After the concrete has set a bit, it'll handle water nicely.  Some curing is done by "ponding" water on the surface, but more frequently burlap is used and kept moist with soaker hoses.  You don't want to get the surface too wet too early before it sets as that can damage the top surface.  Probably not absolutely critical for your application, but it's a good practice to allow it to set a bit before flooding it.

So, if you can keep the soil below dry, and keep excess water out of the mix, it'll be fine.
View Quote
Awesome, those were the concerns.  Thanks.
5/22/2017 8:47:46 PM EDT
[#5]
Some parts of CO has expansive soil that requires special methods.  Better get an engineer, or at least what a local inspector might say.
5/22/2017 8:53:59 PM EDT
[#6]
Quote History
Quoted:
Some parts of CO has expansive soil that requires special methods.  Better get an engineer, or at least what a local inspector might say.
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Very true. another thought would be to line the hole with plastic sheeting and set your tube in that to control water seeping up. I really dont think water is going to be an using the sonotubes.

some steel wire rolled up in the tube might be a good idea to give it some strength. Especially since your dealing with freezing. If I recall correctly, your footers need to be 12" below the frost line.

This is were the local engineer or inspector can guide you.