large blob of concrete - How many lifts?

[DrThink]

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

 

[civilperson]

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.

 

[Zambo]

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.

 

[dicksewerrat]

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.

http://WWW.amlinereast.com

 

[DrThink]

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.

 

[sundale]

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.