[Cob] RE: Stone in cob

[otherfish]

Cob gets it's strength from being built massivly as COB, not something else.
Cob bonds well with cob, but poorly with other materials.  Cob as mortar
will do little more than simply fill the spaces between whatever you are
mortating.  The compressice strength of cob is low comparred to cordwood or
stone.  Using cob as a mortar in a stone or cordwood construction will make
the mortar the weakest link in the wall system.
Not something I'd do.
If you want a mortar that doesn't use portland cement, go for lime sand
mortar.  It haS a long history of successful use as mortar.

john fordice


on 8/16/04 3:51 PM, Bonnie Morse at bonnie.morse at content-mgmt.com wrote:

> My old Materials Science book from college said that gravel with sharp edges
> makes stronger concrete than gravel with smooth edges.  I guess the same
> would apply to sand particles in mortar or cob.
> 
> Bonnie in OR
> 
> -----Original Message-----
> From: coblist-bounces at deatech.com [mailto:coblist-bounces at deatech.com]On
> Behalf Of Amanda Peck
> 
> <snipped>
> 
> A propos of not a whole lot, I've been reading a mystery story involving an
> earthquake.  Author gives lots of information about earthquakes.  Her point
> is that the sizes and shapes of particles in mortar are what is important,
> not all the same, and for sure not all rounded.  (Sarah Andrews, Fault Line)
> 
> 
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