10 concrete slab or is i

huangyhg

10" concrete slab or is it?
we have a project with an elevated 10" concrete slab.  before the pour the contractor put the reinforcing in on chairs then a layer of 1" conduits side by side and then a layer of 2" conduits side by side with no room for concrete to get to the bottom of the slab not mention the area of concrete being displaced.  the slab has deflected and in some places the little bit of concrete that made it to the bottom of the slab is just falling off.  does anyone think there is any alternative but to remove all the concrete in the affected areas and start over.  i personally think the contractor should of known better than to do this.  
jechols - what you describe is totally unacceptable, imho. in fact, it sounds like the slab is "telling" you this by deflecting (under only dead load, i assume). suggest that you take it out.
if necessary, one way to handle objections from the contractor is to have him hire his own engineer (at his expense) to prepare and submit a report to you on why the slab is acceptable - doubt if that will happen.
if i recall correctly, doesn't aci require a minimum of 3 times the conduit diameter for the space between.  it has been years since i dealt with that, but i had a similar issue.  we had the contractor move than before the mud though.
the contractor should also hire his own engineer to propose the method of fix (if anything other than remove and replace).  why should you have to spend your time telling him how to fix his mistake, or take the liability for some sort of remedial repair?
aci 318-99 chapter 6:
conduits shall not significantly impair the strength.
conduits od shall not be larger than 1/3 overall slab thickness.
conduits shall not be spaced closer than 3 diameters or widths o.c.
jechols, i'm curious, what did the electrical drawings show?  do they show those conduits routed together in the slab?  was there an inspection prior to concrete placement, e.g. a pour card?  it is easy to blame the contractor, and maybe he is at fault, but it is also easy for an engineer or drafter to cram a bunch of lines on a drawing.  without drawing them to scale, the lack of space is not apparent.
here is a photo of jecheols' slab

it doesn't look like the reinforcing stayed on the chairs...
this is incredibly amateurish, i can't believe this was a licensed contractor!
classic, thanks slideruleera for the photo.  as they say, a picture is worth a thousand words...
a smart contractor would have submitted an rfi because this was discovered while making a lift drawing.  a regular contractor would have called the engineer out after the conduit went in and said "what do you want me to do now?"  an incompetent contractor would do what was done.
rip it out and fix it.  no extra money, no extra time, just get it done and done right.
i don't think "ripping it out" will take very long. it also looks as if the waste of concrete will be minimal (as hardly any was used in the original cast)it is a clear cut case of demolishing and starting again. the question i have is where are all those conduits going to go next time - spacing at 3 x diam doesn't seem to be the answer!
if that much conduit is required, it should be in a separate chase or use a false floor above the structural floor.  
i agree...this should come out and start over.