[Cob] Curious about the clay

[Robert J Churchill]

I know going in that it's not cheap but money really isn't a problem.  What is a problem is I don't want to build a structure and have it fall down because the clay sucked.  So I'm more interested in experiences with commercial clay or even quarry clay, not just dirt with clay in it.

--- On Thu, 5/7/09, Henry Raduazo <raduazo at cox.net> wrote:
From: Henry Raduazo <raduazo at cox.net>
Subject: Re: [Cob] Curious about the clay
To: rjc2000 at pacbell.net
Cc: coblist at deatech.com
Date: Thursday, May 7, 2009, 5:04 AM

Clay is one of the most common substances on earth as such many people have it
available for free. Just go outside and dig it up. With that said every part of
the earth differs from every other part of the earth. Some people have very pure
clay which shrinks drastically as it dries some have clay and silt some clay and
sand. Others have no clay or so little clay their walls will barely hold
together.
	If you do not have a good supply of naturally occurring clay in your area I
would not recommend building with cob. A fairly small wall that I built in my
house as a heat sink weighs 8 tons. I bought 4 tons of sand ($20.00 per ton) and
mixed that with 4 tons of clay rich soil that came from digging out the basement
of a near by house. The contractor was going to haul the soil 60 miles and pay a
tipping fee to get rid of it, but I was willing to take it for free. Buying that
much clay at a pottery place would be a bit pricey.
	Anyone who would be a natural builder must first be a scientist and then be an
engineer. As a scientist you look around your building cite and ask What do I
have? Rocks? Trees? Clay? All can be converted to building materials. Clay is
one of the most versatile because it has so many uses as a plaster, load bearing
material or refractory. You need to experiment to find the best mix. Sometimes
you need to add sand sometimes just straw. You make bricks and then destroy the
bricks to determine the best combination of materials.
	When you know the best combination of materials then you become an engineer
and ask yourself "How do I make 8 tons of this stuff?" I like to mix
with a rototiller on a slab. You may want to mix with your feet on a tarp. What
ever. You need a lot of stuff to build a house.
Ed
On May 7, 2009, at 1:19 AM, Robert J Churchill wrote:
> The word "clay" is used repeatedly but really where exactly is
all this clay coming from?  I have no idea where I'm supposed to get all
this clay.  For me, it would be easier just to buy clay from a ceramics shop but
I don't even know if that would work.  I live in an urban area and it's
not like we can just go out and dig up clay at a local quarry.
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