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Re: Hollow Core Topping and Conduit

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Conduit in topping---I would be concerned with three things--none really
1. The topping may want to crack at the conduit, as that represents a
weak point in the topping and shrinkage of the topping as it cures and
dries may result in a crack there. The residents in a correctional
facility find pretty amazing ways to destroy things, and cracks are a
great place to start chipping away at something.
2. If there is a crack, how it gets repaired is an issue--the guests
love to chip urethane or silicon fillers out and eat it to get whatever
high is available. Most correctional facility "owners" take this very
seriously--they do not want this. Once the filler is removed, what
happens in 1. above gets easy to do.
3. They also are adept at getting to the conduit, chopping through it
and causing mischief with the wiring inside. The crack is a great way to
start getting to it.

I agree with Harold--if it is indeed single span, why not see if it can
be stuffed in the voids? Or cast in the mold? I do not think that you
can do this with extruded pieces, though. Structurally, you diaphragm is
probably OK with the edge joints grouted well--there is lots of info in
the literature to support that. We have done may such facilities and
usually all conduit is run in bond courses in the CMU walls.......

Good luck!

Richard W. Stone, P.E.
Project Executive
Technical Services/Project Management/Estimating
Concept Design/Engineering/Quality Assurance
Madison Concrete Construction Company
130 Quaker lane
Malvern, PA 19355-2479
email: rstone(--nospam--at)
Voice:       610.695.8800
Facsimile: 610.695.8678
Nextel:      610.496.5764
Visit our webpage at  !!!!

> ------------------------------
> Date: Thu, 9 Apr 2009 19:01:02 -0400
> Subject: Hollow Core Topping and Conduit
> From: gtg740p(--nospam--at)
> To: seaint(--nospam--at)
> I have some 3/8" diameter conduit that needs to be run perpendicular
to t=
> hollow core slab units (perpendicular to the cores) for the entire
width =
> the building. The conduit cannot go below the HC and the HC is 6"
thick w=
> 2" of topping. I don't want to mess up the HC diaphragm topping slab
but =
> don't see any other way to run this conduit and it cannot be placed
> above the topping slab either. Any ideas on how I can still get the
> diaphragm shear transfer if the conduit is embedded in the 2" topping
> I am using a heavy welded wire mesh in the topping slab for the rest
of t=
> diaphragm.
> Will H
> ---

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