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RE: Fibers in Concrete

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I have weighed in on this on the list many times in the past.  Forgive me if
I take the lazy way out and ask you to do a search on the list.  

Summary: Use WWF and avoid the litigation and claims.  By the way the PC
designation is WWR.

Harold O. Sprague

> -----Original Message-----
> From:	Jim Kestner [SMTP:jkestner(--nospam--at)]
> Sent:	Thursday, August 01, 2002 10:13 AM
> To:	'SEAINT'
> Subject:	Fibers in Concrete
> I would like to get some different opinions on using Polypropelene vs.
> Nylon
> fibers in concrete slabs-on-grade.
> Some facts:
> Fibermesh typically recommends 1.5 #/yd and Nycon recommends 1 #/yd. I
> have
> heard of some engineers using as much as 3 #/yd since they say 1.5 #/yd is
> not enough to control plastic shrinkage cracking. (I know it is not a
> replacement for reinforcement.)
> Nycon fibers are more expensive $2.90 vs. $2.30 per pound.
> Fibermesh leaves a "fuzzy" look. Nycon does not. If a floor cannot have
> exposed fibers, like say changing room for swimmers with a bare concrete
> floor where people will be walking on the surface with bare feet, then the
> exposed fuzzes have to be burned off. This added cost may justify the
> Nylon
> fibers.
> Nylon fibers assorbs a small amount of water (3/4 oz per cubic yard).
> Polyproplene is inert, therefore, no assorbtion. I assume no adjustment
> needs to be made in the concrete mix with fibers.
> Some questions:
> It does not appear that Fibermesh and Nycon are equivalent. Fibermesh will
> always win because of price. How can you bid both? Do you spec one and use
> an alternate for the other? Do you write one product out?
> What type of projects are you using Fibermesh vs. Nycon vs. WWF?
> What do you prefer and why?
> Jim K.

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