Using Concrete as Filler in a Tank Cell
Using Concrete as Filler in a Tank Cell
(OP)
I have a client that would like to completely fill a 8'x8'x8' cell in an existing multicell tank and cap it with a reinforced concrete slab. The cell shares two walls with neighboring circular tanks on opposite walls. The other two opposing walls are straight. The intention is to fill the void and cap with a slab to prevent water infiltration into the unused cavity of the cell. The cell was previously filled about halfway with concrete that had formed channels in it to direct flow. The modification uses piping so these channels are no longer required.
The fill this client would like to use is concrete. When filling such a large void with concrete what sort of reinforcing is required, if any? Should the concrete fill have reinforcing bars drilled into the existing cell walls?
If they were to use compacted stone there wouldn't be reinforcing so why use it when filling with concrete? This just seems like a weird detail I was given so I was wondering if there were any engineers with experience in this type of modification to an existing tank structure. I would think that filling the void to the prior height then capping with a slab and post-installed waterstop would be the preferred method. This would maintain the prior design loads on the existing tank, more or less, and still prevent water infiltration.
In any case, I'm still curious on if in this situation any reinforcing or dowels into the existing structure would be necessary.
Thanks for any help!
The fill this client would like to use is concrete. When filling such a large void with concrete what sort of reinforcing is required, if any? Should the concrete fill have reinforcing bars drilled into the existing cell walls?
If they were to use compacted stone there wouldn't be reinforcing so why use it when filling with concrete? This just seems like a weird detail I was given so I was wondering if there were any engineers with experience in this type of modification to an existing tank structure. I would think that filling the void to the prior height then capping with a slab and post-installed waterstop would be the preferred method. This would maintain the prior design loads on the existing tank, more or less, and still prevent water infiltration.
In any case, I'm still curious on if in this situation any reinforcing or dowels into the existing structure would be necessary.
Thanks for any help!






RE: Using Concrete as Filler in a Tank Cell
Consider using flowable fill; supposedly, it can be dug out later if needed, instead of jackhammering it out.
RE: Using Concrete as Filler in a Tank Cell
Keep in mind that even 1000 psi concrete means an ultimate bearing pressure of 144 kips / ft2 (1000 psi x 144 in2/ ft2) - plenty of support for the structural slab.
I agree with JStephen on use of flowable fill.
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RE: Using Concrete as Filler in a Tank Cell
RE: Using Concrete as Filler in a Tank Cell
I'll suggest capping with a slab on grade over the fill with some sort of joint seal or post installed waterstop around the edges.
Who knew a big chunk of concrete required so much thinking!
Cheers!
RE: Using Concrete as Filler in a Tank Cell