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RE: SOG/fibers cont...

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Interesting .  Thanks for the link.
Y'all do things different there.  No way will a cont'r go chair the rebar behind the screed.  Also, most of the bldgs I've done were almost exclusively developer driven (and on very good sandy soil).  Hence "Build it, as cheaply as possible; fill it quickly, and sell it to the equivalent of a commercial "slumlord" is the motto. 
Yeah, they like it when I offer to show them how to do it right, after they've "beeb doing it this way for 30 years".  Why is it always 30?

>>> On 2/14/2008 at 4:00 PM, Harold Sprague <spraguehope(--nospam--at)> wrote:
I have seen a laser screed used extensively on slabs with WWR and with rebar.  The flat work contractor just has to plan for it.  Using a telecoping laser screed, they will chair the reinforcing just prior to placing the concrete in about 10 ft strips and drive on the rebar that is still setting on grade.  They will come back and chair up the next 10 ft strip and place that concrete. 
They also make small hand guided laser screeds that are light enough to run on metal deck or on top of chaired bar or WWR.  Check out the Copperhead laser screed.  Take a look at this web site and watch the video if you want to see it in use.  Then ask the contractor if you want him to show him how it is done;>)
If you do try to screed out a slab, you will become a fan of using WWR 4x4 2.1x2.1 on dobies.  It is an easier platform to walk on as you place the concrete. 
You may want to consider a preplacement meeting with the ready mix supplier, the flatwork contractor, the pumper, and the GC.  Give them all of the information and what the owner expects.   

If the owner and contractor decide they want to use poly fibers, they can.  Just leave your plans alone and let them construct whatever they want without either acknowledging the fibers or approving them. 
I have seen designers give the contractor and owner what they want and then the owner will sue all of the designers when it goes south.  Their argument (and it is successful) is that you are the construction professional and you should have known and advised them properly. 

Harold Sprague

Date: Thu, 14 Feb 2008 13:21:51 -0700
From: JCoombs(--nospam--at)
To: seaint(--nospam--at)
Subject: Re: SOG/fibers cont...

Some good points.  It's not structural.  No reason it (and any other simple non-struct SOG) can't be done by the Arch.  No magic to it.  simple cost/ /risk/ performance issues.
In areas where I've done some work, contr'r have been very resistant because they can use a laser screed.  Can't do that w/ most WWF or reinf slabs.  Fibers apparently worked well, but haven't checked recently.

>>> On 2/14/2008 at 1:58 PM, "Andrew Kester, P.E." <akester(--nospam--at)> wrote:
To expand slightly on this discussion, at my last two companies and my own, we have for some time now been using poly fibers as a replacement for WWR which is up to the GC per our general notes. It has been 1.5lb/cy of 1.5" poly fibers, then it grew to 3.5lb/cy, which may be too much I suppose. But in the end I am now doubting poly fibers effectiveness whatsoever in all but the most microscopic cracks. These are on non-structural SOG, nothing industrial or forklift traffic, etc.
We show CJs on our foundation plan at wall returns, changes in slab direction, columns, etc. and not more than 12'-0" o.c. We take the time to detail these, not sure if they do it.... Also using a Soffcut saw within 4-6 hrs of slab pour or as soon as the concrete is hard enough to walk on, at 1/3 depth of the slab.
Now we rarely get paid on our smaller jobs to go do site visits to review the slabs, so I don't know how they are all performing. I just do not know of any issues we have had or my former companies doing SOG this way in FL, in other words, no comments or phone calls. I know to take all of this with a grain of salt, as the slabs may crack and people just except it. I do not know if is due to our very sandy soil or our warm and humid client, etc. Expansive soils can happen in certain areas but are rather limited.
I agree with Harold that all concrete cracks, especially SOG, and am surprised if I don't see it...  I would like to specify WWR or even #3 bars each way, but no GC or client will likely go willingly along for the ride. I am thinking of adding language on our General Notes that states as it is a non-structural component, we will specify the use of steel reinforcement to LIMIT cracks in the slab. If they want to eliminate it, we will send them a one paragraph form to sign and send back that says they did not use steel at their discretion and they will hold us harmless if the slab's serviceablity is undesireable. Although, I am in no way offering a warranty of any SOG....  I wish we did not even have to spec a non structural SOG, we just don't care. Basically, if they have tile they don't want it cracking and don't want bumps in their carpet.
Any thoughts?
Andrew Kester, P.E.
Principal/Project Manager
ADK Structural Engineering, PLLC
1510 E. Colonial Ave., Suite 301
Orlando, FL 32803

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