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Air entrainment vs hardener

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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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