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Re: Air entrainment vs hardener

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Sounds like the interior requirements are the over-riding factor.  I would
think the amount of exposure on the exterior edge is limited.  Adequate
freeze-thaw protection could be achieved without air-entrainment by keeping
a low water-cement ratio and adequate aggregate control (smaller non-porous
aggregate).  If the low water cement ratio is an issue you could establish a
perimeter construction joint a few feet in from the edge and specify a
different concrete requirement for the perimeter.

Paul Feather PE, SE
pfeather(--nospam--at)SE-Solutions.net
www.SE-Solutions.net
----- Original Message -----
From: "Sherman, William" <ShermanWC(--nospam--at)cdm.com>
To: "SeaInt Listserver (E-mail)" <seaint(--nospam--at)seaint.org>
Sent: Wednesday, November 06, 2002 4:18 PM
Subject: Air entrainment vs hardener


> I'm curious how others solve the following problem: I have a floor slab at
> grade for which a concrete surface hardener is desired in an industrial
> equipment area. The outside edges of the floor slab will be exposed to the
> weather in a freeze-thaw environment (northeast US), but it is otherwise
in
> an enclosed area. The building interior is industrial and the interior
> temperature will be kept above 50 or 60 degrees F.
>
> 1. Should the slab be air entrained due to freeze-thaw exposure at the
> edges? It seems that this is the worst freeze-thaw exposure, right at
> finished grade where moisture and temperature will vary the most. On the
> other hand, will the limited surface exposure and heat from the interior
> reduce the effects of freeze-thaw on the exposed concrete edges?
>
> 2. Air entrainment creates finishing difficulties and is not recommended
for
> trowelled finishes with shake hardeners. (Possible blistering and
> delaminations if not finished properly.) A separate surface applied epoxy
> topping could be applied after the concrete cures, but this would add
> considerable cost relative to a shake hardener.
>
> So what solutions have others used?
>
>
> William C. Sherman, PE
> CDM, Denver, CO
> Phone: 303-298-1311
> Fax: 303-293-8236
> email: shermanwc(--nospam--at)cdm.com
>
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