[Cob] gypsum

[Lance Collins]

Hi Scott,

>The compressive strength as measured by the guys at SW Desert 
>Sustainability while
>I was there was between 200 and 300 PSI. This mirrors the results that the 
>building
>code officials found when using this recipe, so I'm pretty confident in 
>the numbers.
>They use this in Turkey and India by making much thicker walls.  They also 
>have more relaxed codes (if any).

I didn't scientifically test my blocks but they were better than my adobe 
blocks stabililized up to 10% cement which tended to shatter when dropped 
from waist height onto firm ground.  I'm only planning on infill walls anyway.


>Just curious, how did your block weather?

They were only out in regular rain for a couple of months.  Quite water 
absorbent but no erosion.  I suspect that if a wall of my blocks were under 
eaves and possibly treated with a water repellent such as acropol they 
would be quite OK.

Lance

p.s. I moved on to sawdust-crete(?) after this.  Still water absorbent but 
dropable from shoulder height without damage.