----- Original Message -----
From: "Wayne Farrington" <w.farrington@verizon.net>
> The only thing that is still bothering me a little is the concrete spec.
The
> manufacturer states that for a 10K lift the concrete has to be 4in. thick
at a
> minimum, and 3000psi. My building manufacturer tells me the concrete is
> "guaranteed" to be 2500psi minimum (with an emphasis on "minimum", meaning
it
> may be more I guess) and near as I can tell the slab thickness is 5 -
5.5in.
> Of course the required slab thicknesses go up as the lift capacity goes up
but
> I noticed the 3000psi rating remains the same regardless. So I assume that
my
> slightly thicker then required slab does nothing to help my 2500psi
rating?
> Two different specs that are independent of each other?
>
> What do you think? How critical is that 500psi? Is there a inexpensive way
to
> test the psi rating of a slab? Would I be better off to cut two big square
> holes in the slab and pour two 6in. thick, 3000psi pads? I have no idea
how to
> tie them into the existing floor though. I suspect this may do more harm
then
> good by breaking up the "continuity" of the floor. But I'm no concrete
guy.
> Just trying to get a feel for how big a deal this is?
Call the lift mfg. The added thickness may be enough to compensate for the
lower PSI rating, or that could be a number that isn't that important to
them - they may throw 3000 psi in the spec but just want it to be 'enough'.
Better for them to overspec than underspec, from their viewpoint.
Mark.
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