Cob: cob mix

[GlobalCirclenet]

Technically the straw is not the key to brick strengh, but a tiny
percentage of caliche containing lime, given the proper ratio of sand and
clay, more or less. Straw usually helps keep brick from cracking when cured
properly, but it does not bind particles together at all.

paul & barb - on the continental divide
http://globalcircle.net


*********** REPLY SEPARATOR  ***********

On 11/8/2002 at 9:35 PM lightearth at onebox.com wrote:

>Hey Natalie,
>
>From my experience of trying 'test' mixes it sounds like you have real
>clay. The only disintegrating stuff I've run into is silt soil that
>crumbled when made into bricks. I  would make your test bricks thicker AND
>put in alot of straw fiber, well mixed in, as that may be a big key to the
>strength.....
>
>Keep truckin
>
>Marlin Nissen
>
>-- 
>     Marlin Nissen
>   - Outta The Box-
>  lightearth at onebox.com
>(608) 213-9405  Cell/voicemail
>
>
>
>
>-----Original Message-----
>From:     "Espresso Leopard, Betty's Bay" <espresso.leopard at telkomsa.net>
>Sent:     Thu, 7 Nov 2002 20:27:06 +0200
>To:       <coblist at deatech.com>
>Subject:  Cob: cob mix
>
>Hi
>I am starting a small cob project. I have to mix builders sand and clay as
>I don't have clay soil. The clay is grey in colour and dry and in hard
>lumps. I have soaked the clay in some water until it is mush then mixed it
>in differing quantities with the sand without adding more water. I made
>small bricks about 1inch thick. Once dry they are very brittle and break
>easily. Would you say this is the mix, or the clay, or are the bricks to
>thin or is that how they should be? I did a 1clay to 5 sand and 1to 4 and
>1to 3.
>Please help
>Natalie