[Cob] burnt mud

[Amanda Peck]

durned if I know.  Anybody notice in there that they used to coat the 
outside with animal fat, but now use soap?

I ran into this link  These guys, and those in the link below this one, 
don't seem to be adding manure, unless it is ubiquitous in the fields, and 
the burning seems to be used to make pozzolans. And Charmaine just talked 
about them.

http://journalsip.astm.org/JOURNALS/CEMENT/PAGES/154.htm

"Sarooj is a local Omani term for artificial pozzolana produced by calcining 
clays. Calcined clay mixed with lime and water has been used as a cementing 
material for a long time. It has been used widely in hydraulic structures 
due to its good hydraulic properties and in military defensive installations 
due to its durability....  It was also found that the total content of 
silica, alumina, and iron oxide together with the burning temperature and 
the duration of burning have significant effect on the physical properties 
of the sarooj produced."

A little more here:

http://www.newsbriefsoman.info/features/sarooj.htm

The dry pies are then stacked, separated by wadi pebbles on a large pyre of 
date palm trunks.This pebble and palm structure is covered with earth to 
form an airtight seal and firewood is lit beneath it. The firing process 
lasts for about a week. When the fire has died down, the whole heap is left 
to cool. The external covering of earth is removed and all that remains 
including the ash is ground to a powder. The burnt clay is red on the 
outside, white inside. This powder is mixed with water and becomes sarooj.

...................
Copper Harding wrote (snipped)

This was all I could find on the internet.  I am
wondering if anyone has any experience with this
stuff.  Do you know the ratio of mud/hay/manure?  any
ideas on temperature or method of "burning for a few
days"

The fact that it turned water-resistant says that
something chemical is changing?

thoughts? ideas?


 >.In some cases, the roof was laid with a layer of
burned
mud "sarooj",
  >which was introduced from Iran and proved to be
waterproof,
  >
  >http://www.aiys.org/webdate/kearev.html

=====
_________________________
Ms. Copper Harding

If you can walk, you can dance
If you can talk, you can sing  --- from Zimbabwe

When you're out of balance
   gravity tends to get you down. -L.L. Harding



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