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Reply To: | The listserv that doubts. |
Date: | Tue, 13 Nov 2007 05:37:14 -0500 |
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Edison Coatings wrote:
>
> > But as a materials scientist, I have to take exception with your
> classification of natural cement as a pozzolan. Pozzolans are any
> type of reactive silicate (usually glassy or poorly crystalline) that
> require lime to be activated. The reaction is caclium hydroxide (from
> the lime) with the base-soluble silica (from the pozzolan) producing
> caclium-silicate-hydrates, essentially the same primary binder
> material created through the hydration of most cements (natural or
> otherwise).
>
> > John Walsh
>
> John, thank you for your comments, which I always find enlightening,
> knowledgeable and valuable. I was first introduced to the concept of
> cement as a pozzolan during one of the early lime conferences, where
> data was presented comparing the "pozzolanic activity of portland
> cement" vs. brick dust, clay and a handful of other materials. I don't
> doubt that you are correct on this point, and that cement is not a
> true pozzolan as you have defined it. So I wonder if the terminology
> hasn't now been redefined, even if only by common usage, however
> incorrectly, to include anything that reacts with lime to form calcium
> silicate hydrates?
>
> Mike E
>
John & Mike,
I hate to ask at the risk of putting the chemical phobic to sleep but is
there a place that I can go look online to see an illustration of the
creation of this calcium-silicate-hydrate binding? I am curious why they
are tenacious. Are there more electrons shared?
John: and welcome to BP.
thnx,
Ken
--
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