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Re: SLAB - Control Joints in Concrete Slab on Grade

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Time for a dumb question.

So why use Fibermesh if it cannot/should not be used as a replacement for
WWF?

Regards,
Bill Allen

-----Original Message-----
From: Dennis S. Wish <wish(--nospam--at)cwia.com>
To: seaoc(--nospam--at)seaoc.org <seaoc(--nospam--at)seaoc.org>
Date: Saturday, April 25, 1998 2:29 PM
Subject: RE: SLAB - Control Joints in Concrete Slab on Grade


>I believe that you have been very lucky with the use of Fibermesh. If you
>review the product literature, I believe you will find that the company
does
>not recommend the use of Fibermesh as a replacement for reinforcement or
>even WWF to control temperature cracking. I had a contractor substitute the
>additive for WWF in some small tract homes that I designed. In residential
>construction, the care and quality during the curing process of concrete is
>very poor. Each of the slabs cracked considerably in the first three
weeks -
>more from the fact that the slab was allowed to sun dry while it was curing
>and no care was given to keep it moist.
>Fibermesh is suppose to be used in commercial and industrial slabs to
reduce
>temperature cracking in slabs with appropriate reinforcement - not as an
>alternative to. You can argue that on residential projects not designed to
>Federal lending conditions, there is not code requirement for either welded
>wire fabric or reinforcing - except for continuous steel in the perimeter
>foundation or slab edge.
>I would caution any engineer who is led to believe that Fibermesh is a
>replacement to temperature steel - I have met some very disappointed
>homeowners and contractors who had to spend the money on Epoxy injection to
>correct the conditions.
>That's my $0.02 worth.
>
>Dennis S. Wish PE
>
>
>-----Original Message-----
>From: Bramhall [mailto:mab(--nospam--at)nwlink.com]
>Sent: Saturday, April 25, 1998 5:58 AM
>To: seaoc(--nospam--at)seaoc.org
>Subject: Re: SLAB - Control Joints in Concrete Slab on Grade
>
>
>I have used Fibermesh in slabs-on-grade in lieu of wwf for two or
>three projects for the same owner.  I think it works quite well
>but great care must be taken in the early stages of the slab to
>ensure excess shrinkage does not occur.  If Fibermesh (or an approved
>equal) is to be used in lieu of steel reinforcing, ALL parties
>involved (owner, architect, SE, contractor, testing agency, etc.)
>need to be keenly aware of the unique advantages and shortcomings of
>fiberous reinforcing.
>
>The deletion of the wwf in these projects was a result of a value
>engineer process for the first project and became the "standard" for
>the subsequent projects.  The slabs under the office buildings
>turned out very well but very large random cracks appeared in slabs
>under the fre standing parking garages.  The cause of this cracking
>was due to the fact that the slabs in the garage were exposed to the
>elements (direct sunlight, warm temperatures and breeze) while the
>slabs under the buildings were protected (formwork and basement
>walls) as soon after being finished.  Once the cracks in the garage
>slabs had reached a certain width the Fibermesh was of no use and no
>backup method remained to distribute the shrinkage throughout the
>slab.  We ended up epoxy injecting some of the smaller cracks and
>replacing a few other sections (20'x20').
>
>
>Michael Bramhall, PE
>
>
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