Cob: lime and pozzolans

[Darel Henman]

Amanda Peck wrote:
> 
> BUT I winced when I heard them talking about quicklime. .......
> Quicklime is DANGEROUS!

It can be dangerous if you don't know what you're doing.  Matches and
ammonia to for that matter.  But, it has many applications.  For
example, it's used to quickly heat instant meals out in the field (pull
a string and a quicklime pellet falls into some water inside the boxed
lunch), you have a warm lunch. 

In the old days quicklime with water poored over it was used to steam
sweet potatoes and is nostalgic to those who talk about it.   Remember
those days.....     So as Amanda said it can be dangerous because of the
chemical transformation when it comes into contact with H2O and produces
steam which can burn you if not handled correctly.

Darel
 
> "Materials which enable lime mortars to set more rapidly include ash
> and brick dust. Known as 'pozzolans' after the volcanic additives used by
> the Romans, these materials are widely found in the lime mortars used in
> old buildings and monuments."

I don't know about pozzolans making a quick set or not, but they do make
for a stronger lime-cement.
The roman version was capable of setting in water.

Darel