[Cob] Burnt clay-FIreclay Kaolin

[dirtcheapbuilder-Charmaine Taylor]

On Jun 21, 2005, at 7:26 AM, Marlin Nissen wrote:

>>   Hello!
>>     I am trying to make roman concrete for mortaring
>> an urbanite
>>     foundation,
>>     and am needing some powdered burnt clay. I
>> wonder if anyone has ever
>>     heard
>>     of this, and if so, where to get it? I need it
>> for this weekend, so
>>


Yes it looks like you want something that will be more pozzolanic... if 
all else fails try buying "Fire clay-mortar clay" it is purse silica 
clay and is used for pottery.. it itself is NOT burned, but it is a 
fine grain Kaoilin clay whch will stick like glue to any lime..and wont 
swell.

  I use it all the time to fill out a sandy clay harvested here.

It is cheap at a builders supplier.. hardware or sometimes feed store.  
the bag will say FIRE CLAY or Masons clay-   locally   L Muddux Co in 
Sacramento mines it right from the ground,,and it is used by  cement 
guys to add to an OPC mix and plasticize the cement I think.

  the instuctions on the bag will say add 6 parts clay to 1 part cement, 
etc sand,  to make mortar.

  they are $3-4 for a 50 # sack.  the same ( a bit finer) in a pottery 
store is 10X the price

Kaolin can be mined right from the earth, sifted and sold.. it is  all 
over in Boron CA... I got a bag of pale pink Kaolin un-processed and it 
acts the same as the grey fire clay.

>>
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