[Greenbuilding] Redoing all floors

[Ktot (g)]

Interesting. Mine was 11 days from pour to seal. Stain was applied just 2-3 
days after pouring. The company that did the staining/sealing also did the 
pouring so they knew the mix they used. Talking to various experts, at least 
28 days should have been left between pour and cure. Even the sealer specs 
say at least 14 days at 70 degrees and this was at about 30 degrees. 
Furthermore, moisure was apparently added from the diesel and propane 
heaters the contractor used to try to speed up drying. That may also have 
caused some of the calcium carbonate that formed.

----- Original Message ----- 
From: "RT" <Archilogic at yahoo.ca>
To: "Green Building" <greenbuilding at lists.bioenergylists.org>
Sent: Wednesday, July 27, 2011 2:23 PM
Subject: Re: [Greenbuilding] Redoing all floors


> On Wed, 27 Jul 2011 14:29:13 -0400, Ktot (g) <ktottotc at gmail.com> wrote:
>
>> I explained that in my initial email--less than half the required curing 
>> time for the concrete. Thus moisture is trapped under the sealer
>
> Actually, one of the reasons that sealers are applied to new concrete is 
> to prevent premature loss of the mixing water (evaporation) so that the 
> cement in the mix has an opportunity to fully hydrate, thereby bettering 
> the chances of a good quality concrete ... so "trapped" is a Good Thing.
>
> The strength vs time curve for concrete pretty much levels off after ~30 
> days
>
>   http://www.theconstructioncivil.com/2009/09/concrete-curing.html
>
> so one should try and keep the mixing water from evaporating or being lost 
> to the substrate during that "curing" period.
>
> I prefer to simply keep the green concrete tightly covered with a 
> protected polyethylene sheet during that curing period but a chemical 
> sealer is the more common choice. ("Protection" being cut-off scraps of 
> sheet goods like OSB, plywood or even gypsum board)
>
> Too often though, for the sake of finishing expedience, the mixing water 
> is allowed to evaporate too rapidly (and/or lost to the substrate , there 
> being no moisture barrier used beneath) and then is followed by repeated 
> soakings/subsequent evaporations after (improper at that) finishing -- all 
> of which lead to poor quality concrete that is weak, dusts/abrades easily, 
> much of the cement having been leached out of the mix (ie quite likely the 
> whitish "blooms" than Ktot mentions).
>
> And oftentimes, water is added to the concrete mix during placement to 
> make placement and leveling easier. That too messes up the all-critical 
> water-cement ratio which seriously compromises the concrete quality.
>
>
> -- 
> === * ===
> Rob Tom
> Kanata, Ontario, Canada
> < A r c h i L o g i c  at  Y a h o o  dot  C A >
> (manually winnow the chaff from my edress if you hit REPLY)
>
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