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large blob of concrete - How many lifts?

large blob of concrete - How many lifts?

large blob of concrete - How many lifts?

(OP)
I have a 150 kip 11 feet diam. tank that I am doing a foundation for.  There are basements of an existing buildings directly adjacent to the tank.  I was thinking of pouring a 10' deep x 12'X12' concrete blob in the ground to ensure no lateral pressure against the basement walls.  

I was planning on using lean concrete.

My question is:
Do I have to worry about heat of hydration for this much concrete?  What lift htg is acceptable and how much time between lifts?

I was planning on using type IIA concrete.  Not too concerned if there is minor cracking.

Thanks

RE: large blob of concrete - How many lifts?

Concrete with a least dimension greater than five feet must consider heat of hydration for the mass.  The soil pressure will exceed 3 ksf.  Multiple thermometers cast in various locations will help prove that minimal thermal gradient (from interior to exterior) existed.

RE: large blob of concrete - How many lifts?

your foundation is not very large 3.6m x 3.6m x 3m. You state you are going to use lean mix concrete. I do not think you will have a problem with heat of hydration.

Are you concerned that the concrete pressure during casting will cause the basement walls to fail.

RE: large blob of concrete - How many lifts?

I'd use a concrete mix with about 40% flyash. that should control your heat and still keep the strength above 2000 psi. Place in three lifts and you shouldn't damage the neighbor's basements.

Richard A. Cornelius, P.E.
WWW.amlinereast.com

RE: large blob of concrete - How many lifts?

(OP)
Thanks for the responses.  I may use flowable fill.  But it is actuall more expensive in this area.  The basment wall will be shored on a temporary basis during construction.

RE: large blob of concrete - How many lifts?

Does the tank have significant lateral loads?  Any wind or seismic base shear might not be able to mobilize passive soil pressure with an adjacent below grade building. I would consider demonstrating any base shear was resisted by pure friction at the base of your flowfill pad.

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