[Stoves] Calculation help in brick making

[frank at compostlab.com]

Crispin,

Thanks again - I like "off-the-wall" ideas. If you have more send them on!
You mention phosphates but I bet it is polyphosphates that is in the detergent. 

If you have suggestions on some experiments you would like to see, and I have
the equipment, perhaps I could run some for you. 

Frank  





On Fri, 29 Jun 2007 12:46:10 +0800, Crispin Pemberton-Pigott wrote
> Dear Frank
> 
> Something else to strengthen your brick - a little more off-the-wall 
> - is a compound sold for stabilising roads and making them 'waterproof'.
> 
> A company was selling a super-secret compound that was used in an extremely
> diluted form to compact and stabilize/waterproof rural roads.  There 
> was a lot of raving about how effective it was in their brochures. 
>  They did not claim that it actually made the road waterproof, they 
> just claimed it worked really well.
> 
> The stuff was apparently very acidic/(or basic) and came in a 210 litre
> drum.  This drum was sold at a fantastic (high) price.  It was 
> diluted into 200 drums of water for use, and then mixed with a 
> further enormous dilution into many many cubic metres of soil which 
> became the base of the road.  It was in the end very diluted so the 
> original cost was spread over a long stretch of road.
> 
> Someone I know had this stuff analysed and found it was extremely
> concentrated Sunlight Soap (dish washing liquid).  The reason it 
> works is that it is a surfactant.  It reduces the electrical charge 
> on the particles and allows them to slide past each other more 
> easily.  The hydrophobic part of the 'soap' attaches itself to the 
> particle and the hydrophilic part allows the water to penetrate 
> farther/nearer (improving lubrication).  When compacted at any given 
> pressure/vibration, the density is higher, reducing the air space 
> volume, reducing permeability, increasing load bearing capacity and 
> therefore wear resistance.  When dried, the water lubricant is gone. 
>  Obviously it will allow you to use less water which has its own 
> benefits as discussed earlier.  This also applies to forming Rings 
> and other stove parts from clay though these days I am optimistic 
> about phosphates for very different reasons.
> 
> If you were not using hand methods to form the adobe bricks, you 
> could gain benefit from adding (and uniformly distributing) a 
> (really) small amount of dish soap. I would not be surprised if you 
> could get 400 PSI or more with this method, but you won't get it 
> with slop-moulding because there is no pressure involved.
> 
> If you can get the density of a brick up 5% there is a huge increase 
> in load bearing capacity - perhaps 50% or more. I can't remember the 
> line we drew at the Transkei Appropriate Technology Unit but it was 
> significant. Surfactants are a good, cheap way to do get big numbers.
> 
> Regards
> Crispin
> 
> PS I am wondering if you can get a low power microwave oven to dry your
> samples very slowly - in part with low power and in part by putting 
> in a large sample.  It might heat it evenly throughout the thickness 
> and given a uniform shrinkage.  Some ovens will cycle on and off to 
> assist the lowering of the average power.


--
Frank Shields
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