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RE: SOG/fibers cont...

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You might want to consider crusher fines over the vapor barrier in lieu of the sand.  It compacts better and provides a good surface on which to set the dobies for the rebar support. 

Regards,
Harold Sprague


Date: Thu, 14 Feb 2008 15:06:16 -0800
From: bruckmandesign(--nospam--at)verizon.net
Subject: RE: SOG/fibers cont...
To: seaint(--nospam--at)seaint.org

Further expanding on the SOG discussion, I am thinking of moving toward altering my SOG construction technique and specs/drawings to eliminate the “aggregate sub-base” in favor of using regular compacted ASTM Class 2 roadbed and then a topping of sand over the moisture barrier.  I’ve been very unhappy with the mess made by rod-busters to the sub-base when rebar is spec’d over the standard rock/visqueen/sand arrangement.  It doesn’t compact well and by the time the rebar is down, with all the footprints and stuff, you’d hardly know the sub-base was ever rolled flat to start with.

I suppose this would be a soil engineer’s call, but I’d think the structural engineer would like the idea and its certainly easier to construct.


From: Jerry Coombs [mailto:JCoombs(--nospam--at)carollo.com]
Sent: Thursday, February 14, 2008 12:22 PM
To: seaint
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)cfl.rr.com> 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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