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Re: 1-3/4" roof slab (w/ 6mm RSB @.10 for S.S. and .20 @L.S.)

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Dear Lew,

  The  1-3/4" slab is reinforced with 6mm @ 4"
o.c. short span and 8" o.c. long span.
The 6mm steel is placed at the center of its
thickness. The bottom slab will  also be
plastered with 3/4"  1:3 cement plaster mix
although the structural function of the bottom
plaster is neglected.  Top and bottom cover is
1.5" which is the  minimum allowed except for
the expanded metal which has only 1/2" cover.

Thank you for your comments and best regards.

Sincerely,


ALEX C. NACIONALES,C.E.
Iloilo City, Philippines




Lew Midlam wrote:

> In my opinion, you have a 1-3/4 thick
> UN-reinforced concrete slab, with   1"   of
> dead load
> plaster on top of it.  The plaster wil not
> provide sufficient corrosion protection for
> the
> metal, and in a few years it will corrode and
> expand, resulting in delamination of the
> plaster
> from the concrete slab.
>
> If this is the case, then the dead load of the
> plaster + the 30 PSF live load would cause the
>
> concrete to be over-stressed.  However, note
> that UN-reinforced concrete is not permitted
> for
> this type of construction (ACI 318-95, para.
> 22.2.2).
>
> My $.02
>
> Regards,
>
> Lew Midlam
> ==============================
>
> Alex C. Nacionales wrote:
>
> > Dear Lew,
> >
> > The 1-3/4" slab is one way and supported by
> > 6"x12" RC beam on fours sides. The slabs and
>
> > beams were poured first then the expanded
> metal
> > was placed on top of the slab and
> > and cement plaster 1:3 mix of washed sand
> and
> > portland cement type I was applied and
> cured.
> > Construction is complete now. I will  send
> you a
> > picture if you are interested.
> >
> > Sincerely
> >
> > ALEX C. NACIONALES, C.E.
> > Iloilo City, Philippines
>
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