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Post by Deleted on Jan 8, 2018 7:10:39 GMT -8
Dehydroxylation of kaolinite starts at about 550°C/1022°C and is quite complete at 630°C/1166°F,
thus virtually every owner of a batchbox has a kiln sufficient for that.
If one places a tin can with one pound of clay powder into the batch box by two fires a day it will be a full sack at the end of a month.
Of course other clays can be used as well.
The upper chamber of a DSR provides much higher temperatures,
which may solve the problem of the very high water demand by giving a denser result.
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Post by etownandrew on Jan 8, 2018 10:01:30 GMT -8
Karl, What do you see as the advantage or use of Metakaolin, Metaclay?
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Post by Deleted on Jan 8, 2018 10:36:17 GMT -8
Contrary to natural clays dehydroxylated clays are chemicaly very reactive.
For a LTGS binder one can deviate with metaclay from the standard 1/1 ratio
and use a higher mineral/lye ratio of 2/1 or 3/1.
A higher mineral/lye ratio allows to use more binder without getting into insanely high amounts of lye in the final mixture.
Metaclays can also react with waterglass.
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Post by coastalrocketeer on Jan 8, 2018 20:03:53 GMT -8
... Also some quicklime can be used to shorten setting and thus prevent segregation. See also: Metakaolin, Metaclay from the Batch Box... Karl from your other Metaclay post I assume it is related to quicklime, but this comment (above) is unclear. Since the production technique of quicklime is the same as your description of making Metaclay, are they closely related in properties? If so, why not explain that in your quoted post? Both metaclays and quicklime are dehydroxilated minerals and thus chemically very reactive. In the chemical sense metaclays are salts. Quicklime is an oxide of an earth alkali metal, which by hydration releases large amounts of heat. The released heat makes quicklime much more reactive than hydrated lime. Related info from the answer to a question on this subject in another geopolymer thread... |
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Post by esbjornaneer on Feb 2, 2018 1:02:36 GMT -8
Just to make it super clear to me: The metaclay would only be used to make the binder? There is no advantage in using metaclay as the aggregate?
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Post by Deleted on Feb 2, 2018 6:50:36 GMT -8
Metaclay also as aggregate would give a stronger result.
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Post by esbjornaneer on Feb 2, 2018 8:22:42 GMT -8
Would this 'stronger result' mean that it is also less insulative, as has been indicated in scientific articles: more structureal stength = less insulative effect <=> less structural = more insulative?
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Post by Deleted on Feb 2, 2018 9:14:45 GMT -8
Mass and thermal conductivity of natural clays will be lowered when the hydrates are driven out at high temperatures.
This cannot happen in geopolymers made only of metaclays.
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Post by esbjornaneer on Feb 2, 2018 12:04:56 GMT -8
Sorry Karl I'm not sure I understand your last post. I hope I will if you would rate from most insulative to least (assuming that particle size is the same, moisture content the same, and any other factor that may alter the insulation value is the same):
natural clay binder with natural clay aggregate
metaclay binder with natural clay aggregate
metaclay binder with metaclay aggregate?
And another question: Does the metaclay need to be stored in any specific way to not loose its 'meta' quality? (Quicklime, CaO, needs to be kept suficiently separated from water, including air moisture, to not react, is it similar with metaclay?)
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Post by Deleted on Feb 3, 2018 6:58:03 GMT -8
The out driven hydrates leave small voids.
The more of natural clay the more voids.
Metaclays are not as hygroscopic as CaO,
but have an electric surface charge and thus can attract water molecules.
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Post by esbjornaneer on Feb 3, 2018 10:26:26 GMT -8
Thank you Karl.
So to state the obvious:
natural clay binder with natural clay aggregate > metaclay binder with natural clay aggregate > metaclay binder with metaclay aggregate
with regards to insulation value.
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