Cob Clay, Fibers, & FC

[Keftydia at aol.com]

Will writes:

<< What is pine straw? Is it the smooth pine needles you are referring too? >>

Pine straw is what we Southerners call fallen pine needles.  The needles
discolor from a dark green to a rusty brown color.  With long-needle pines,
the straw may reach lengths of anywhere from 6 to 10 inches (or 15 to 25 cm).
So the fibers aren't terribly long...certainly not like regular straw.

<<The best way of finding out what clay works best in your situation is to
make test bricks of varying proportions of clay sand & earth that are
available at your site.>>

I have made test bricks.  I think most of them turned out too sandy (the sand
would just slough right off...or is this normal with dried cob?).  The tensile
strength was poor, although the compressive strength was amazing.  Tomorrow I
plan to try some other mixtures and see what I get.

Thanks for the tip on Roman cement...anyone have a recipe for this?

Metta to all,

Ron Cameron




In a message dated 10/16/98 5:29:43 PM Eastern Daylight Time,
wfirstbr at wcb.bc.ca writes:

<< Hi Ron,
 
 The best way of finding out what clay works best in your situation is to make
test bricks of varying proportions of clay sand & earth that are available at
your site. For each brick, record its recipe and when dry compare its
properties, such as strength, weight, cracking, does it crumble, easy to break
or is it rock hard. Some clays have quite high silt content making them less
suitable. Stickiness is a good indicator as the clay is basically used as a
glue.
 
 Fiber cement would probably work ok for non-load bearing interior walls. But
you might also want to consider other alternatives such as clay straw which is
also cheep and doesn't need custom mixing machines, or thin burlap bags filled
with stabilized earth and wood chips, or other combinations. You could also
use other natural recipes such as roman cement which has held up the Roman
aqueducts for the past 2000 years. I have forgotten its recipe but it is light
and strong. I would look towards using available natural materials that are
close at hand (on your property) for the best return.
 
 What is pine straw? Is it the smooth pine needles you are referring too?
 
 Regards,
 Will >>