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RE: Slab on grade

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Reinforcing is to be placed per ACI 301, Section 3.3.2 (if you require ACI 301).  The contractor is in violation of the specs if he does not "Place, support, and fasten reinforcement as shown on the project drawings."  All the major flatwork contractors place their reinforcing on supports of some kind.  I don't give smaller contractors a pass.  I have no problem writing up a deficiency report. 
 
Further, "Hooking" WWR is prohibited in ACI 301:

3.3.2.5 Welded wire reinforcement—For slabs on ground, extend welded wire reinforcement to within 2 in. of the concrete edge. Lap splice edges and ends of welded wire reinforcement sheets as shown on the project drawings. Unless otherwise specified or permitted, do not extend welded wire reinforcement through contraction joints. Support welded wire reinforcement during placing of concrete to maintain positioning in the slab. Do not place welded wire reinforcement on grade and subsequently raise into position in concrete.

 
It is not a "methods and means" issue if it is specifically listed in your specs and in ACI 301.  Otherwise how do you determine compliance with ACI 117?  The contractors must support it somehow.  Whether they use dobies or bolsters could be "methods and means" unless you specify one or the other.  But reinforcing is to be supported and fastened. 
 
I hear that "we do it all the time".  Longevity of code violation is not a good defense. 
 
Use a heavy WWR and they will not bend it down by walking on it. 

Regards, Harold Sprague



> Date: Mon, 10 Nov 2008 08:26:12 -0500
> From: gtg740p(--nospam--at)gmail.com
> To: seaint(--nospam--at)seaint.org
> Subject: Re: Slab on grade
>
> I have stated the WWR to be placed on dobies before on my drawings,
> but they end up pulling it while pouring anyway. They try to make it a
> means and methods issue. How do you make them always use the dobies?
>
> WH
>
> On Sun, Nov 9, 2008 at 5:59 PM, Harold Sprague <spraguehope(--nospam--at)hotmail.com> wrote:
> > As much complaining as I hear, I thought we would be talking megabucks
> > difference, but when push comes to shove, there is no difference.
> >
> > I insist on dobies and using a 4x4 WWR makes it easier to walk on.
> >
> > Regards, Harold Sprague
> >
> >
> >
> >> Date: Sat, 8 Nov 2008 20:14:39 -0500
> >> From: gtg740p(--nospam--at)gmail.com
> >> To: seaint(--nospam--at)seaint.org
> >> Subject: Re: Slab on grade
> >>
> >> In my area the WWR is always pulled into place during pouring, so the
> >> location is not so reliable. But it is used way more often than
> >> rebar.
> >>
> >> Does anyone have a relative cost comparison between using installed
> >> rebar vs WWR that would provide the same steel area? Say #3 at 18" vs
> >> WWR?
> >>
> >> Will
> >>
> >> On Sat, Nov 8, 2008 at 7:30 PM, Harold Sprague <spraguehope(--nospam--at)hotmail.com>
> >> wrote:
> >> > It depends on the gauge of the WWR and the spacing of the dobies. The
> >> > #3's
> >> > with dobies at 4' o.c. will (in general) rebound easier than lighter
> >> > gauge
> >> > WWR.
> >> >
> >> > Regards, Harold Sprague
> >> >
> >> >
> >> >
> >> > ________________________________
> >> > From: Rhkratzse(--nospam--at)aol.com
> >> > Date: Fri, 7 Nov 2008 19:12:10 -0500
> >> > Subject: Re: Slab on grade
> >> > To: sgordin(--nospam--at)sgeconsulting.com; seaint(--nospam--at)seaint.org
> >> >
> >> > Is a #3 much better than WWF after a few hefty guys walk all over it?
> >> >
> >> > Ralph
> >> >
> >> > In a message dated 11/7/08 12:00:50 PM, sgordin(--nospam--at)sgeconsulting.com
> >> > writes:
> >> >
> >> > This means that in your 4" slab, rebars at 12" spacing do not
> >> > necessarily
> >> > have to be #4, they can be #3 placed about 1.25" below TOC.
> >> >
> >> >
> >> >
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