[Stoves] Brick making problems

[Crispin Pemberton-Pigott]

Dear Frank

This crack is an example of adhesion of the brick to the support underneath.
It is interesting that you did not mention any other significant cracks.
The brick is so big and so soft that the friction between the bottom and the
surface it is sitting on is enough to prevent the brick shrinking normally
(and get shorter).

Pouring a mud mix is a way to just about guarantee significant shrinking.
Try to reduce the water content to a paste instead of wet enough to be 'slop
moulded' as we call it.

You can a) add chopped straw/grass to give it more strength so that when it
shrinks it will pull the dead weight of the brick ends towards each other
instead of breaking, or b) put something underneath so it can slide (like a
bed of sand) or c) as soon as it can be turned, put it on edge to dry, and
stack them near each other.

It sounds like they are not being used to keep each other damp as they dry
very slowly.  There is a good example of drying slowly at
http://www.newdawnengineering.com/largeimage.php?imagename=tbric015.jpg&retu
rnpath=/website/brickandtile/tbrick/index.php

You bricks sound too big to stack on end but don't rule it out. Perhaps
stacked against a strong wall. If you can pick it up (barely) and get it off
the ground it will be less likely to break as the drying progresses.

Good luck!
Crispin


-----Original Message-----
From: stoves-bounces at listserv.repp.org
[mailto:stoves-bounces at listserv.repp.org] On Behalf Of frank
Sent: August 13, 2007 9:23 PM
To: Discussion of biomass cooking stoves
Subject: [Stoves] Brick making problems

Dear brickers,

I am working with the local park service that has the task to rebuild 
the two ends of a two story building (Castro Adobe)  that cracked 
(badly) in the 1989 earthquake.