[Stoves] Brick making problems

[David Whitfield]

Global warming effects????
;-)
On Aug 14, 2007, at 2:44 PM, frank wrote:

> Dear Crispin, David and others,
> The bricks seem to be cracking starting from the surface.  Not from  
> the
> bottom as I would have expected.  The center -bottom is still very  
> wet.
> The ground under the brick is very wet with a 'seal'  at the bottom of
> the brick. The brick has been covered with kraft paper on top and  
> sides.
> Straw was added to the mix and broke like someone cut it with a knife.
> Even the newer bricks made of local material are cracking in large
> numbers. The bricks only shrunk about 0.5 inches on all sides. We have
> no rain and only mild temperature.  Water is hosed onto the kraft  
> paper
> three time a week (?) but I don't think it penetrates to the brick.  
> They
> crack before they are dry enough to stand up.
>
> I brought back a brick to the lab and plan to do a pattern analysis of
> the moisture.
>
> I wonder about:
> 1) when making the bricks to place them on top of the kraft paper or,
> perhaps sheets of plastic so they slide ?
> 2) using cloth like burlap on top that will soak up the water?
> 3) add calcium like gypsum or lime to make the particles more  
> sticky and
> reduce shrinkage (resulting in a less dense brick).
>
>
> something like that
>
> Thanks
> Frank
>
>
>
>
> Crispin Pemberton-Pigott wrote:
>
>> 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.
>>
>>
>>
>>
>>
>>
>
> -- 
> Frank Shields
> Soil Control Lab
> 42 Hangar way
> Watsonville, CA  95076
> (831) 724-5422 tel
> (831) 724-3188 fax
> frank at compostlab.com
> www.compostlab.com
>
>
>
>
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David Whitfield
lists.cedesol at gmail.com
-------------------------------

"We make a living by what we get... we make a life by what we give."  
- unknown author

David Whitfield V.

Executive Director

CEDESOL Foundation

Alternative Education, Renewable Energy, Social Equality

http://www.cedesol.org


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