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RE: Swimming pool concrete fill

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I think the term "flowable fill" is a new term and you might ask the ready-mix plants for a lean concrete mix, or just a standard concrete mix with only 1 c.y. of cement in it.  Some people call this a 500 psi mix or a "diggable" mix.




From: Jim Wilson [mailto:wilsonengineers(--nospam--at)]
Sent: Wednesday, September 19, 2007 11:55 AM
To: seaint(--nospam--at)
Subject: Re: Swimming pool concrete fill


Thought about the sand - they are concerned that existing cracks in the pool and a high water table could lead to erosion of the sand.  Maybe wrapping it in a 6mil barrier would protect it adequately.  Then again, there could be an issue with slab uplift on sand when they drain the pool, especially if they drain it in the winter months.


Flowable fill is great, but I've tried the redi-mix plants on this before and they really don't know the product.  The volume doesn't warrant the hurdles.  This is the Poconos after all....


Gravel could work, but they like the speed with which the hole can be filled with concrete.


And for the record, this is not an engineered design and I am not sealing or stamping or detailing anything.  And I'm not about to formally design an infill slab on fill within an existing non-engineered pool.  I'm just raising issues for an old-time mason and a site superintendent to think about.





"Jordan Truesdell, PE" <seaint1(--nospam--at)> wrote:

If you plan on a slab on top, presumably placed with reinforcing to
control cracking, could you do the first placement of the bulk material
with a flowable fill (250+/-psi) mix, or even a compacted, well-graded


Jim Wilson wrote:
> A client intends to fill a 9' deep pool with 5' of concrete to make a
> wading pool for the elderly. Are there any particular concerns with
> the mix design to mitigate chemical reactions between pool chemicals
> and components in the mix? If not, would a simple 3000lb or
> 4000lb mix suffice? I am thinking that they should place the final 6"
> in a separate lift to reduce cracking and facilitate finishing.
> The client expects to have a cold joint around the perimeter that will
> need to be sealed. They intend to drain and repaint the pool every
> year, so maintenance of the joint will not be too great of an issue.
> Jim Wilson, PE
> Stroudsburg, PA

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