[Cob] Land search...pressed earth blocks vs. cob

[Michael Fitzgerald]

Hi all:

As far as I know I'm the only one using a civa-ram. I don't know how
somebody got the idea that I was using cebs for ceiling tiles. I have seen
on the web, tool set ups for making concrete roofing tiles, but I have not
tried these yet. I have however bought a Cinva-ram and am now in the process
of filling in the blanks between dreams and promise and the muddy reality of
making cebs.

Somebody here says that making cebs save time over cob. I don't think that
this is true. Using my one brick at a time ram, I am able to make about
80-100 brick in a day. That's working in the summer with daylight from 6:30
AM to 9:30 PM. (Maybe I did take an afternoon siesta for an hour or two, but
my back was sore!) I wasn't too surprised at the amount of work nor the pace
at which the work proceeds. What I did discover only after the fact was that
all of the dirt used for cebs should be screened. When I was in Africa and
used a Cinva type ram we didn't screen the dirt at all. My dirt needs
screening. So this is an additional process that we are working through and
trying to make it efficient. Dirt weighs a lot and it really sucks to move
it more than necessary. My hole is in the back of the property and my barn
and brickyard in the middle so I have been using my little tractor and the
slightly- bigger- than- a- wheelbarrow- dump- trailer- attachment, for the
screening process. I use a wire mesh that is 1/2x1, 12 gage welded wire. The
kind you use for building rabbit cages.  Staple a couple of twobyfers to it
and it sits on top of the trailer. Shovel dirt onto it and I use a hand
sized rock to break up the clods (dirt not my work assistants) and smoosh it
through the screen. Pebbles are brushed into a pile that is getting pretty
sizeable. Can you say pebble mosaic? I have tried to make cebs without
screening my dirt and the quality of the block was impossible to control. I
had a bunch crack on me as I ejected them. I did try to make a block with a
coblike mix of mud and straw. It did not work well. Cebs have to be made
with a minimal water content. The amount of water in a mud mix that is
necessary in order to mix straw into it, is way to wet for a proper ceb. I
was barely able to eject the block and it shrank and warped when it finally
dried.

One of the good things about cebs and time is that you can work at them a
little bit every day and you don't have to wait for cobbing weather. I have
made cebs while it was pouring rain. I am still making them now though the
temperature gets down to the mid 30's at night and we've been having rain
and 40's for highs for the last 3 weeks. I can get about a dozen cebs made
in about an hour after work. If you had a crew and could split up the
different stages digging, screening, mixing, molding, stacking, etc., You
could probably increase your output significantly. I haven't any recent
pictures however here is link to some I posted a few months ago.
http://f1.pg.photos.yahoo.com/ph/coyotemike3769/lst?.dir=/CEBs&.src=ph&.orde
r=&.view=t&.done=http%3a//f1.pg.photos.yahoo.com/

If you are truly considering the Cinva ram you should read thoroughly the
two BASIN publications on CEB manufacture and it structural usage.
http://www.gtz.de/basin/publications/books/CEBVol1.pdf and
http://www.gtz.de/basin/publications/books/CEBVol2.pdf.

A little update for Darrel. You were asking me what kind of mortar I was
going to use. Well I bought three bags of store-bought pre-mix mortar. This
material was expensive and did not go very far at all. So to save money and
move the project forward I did use your suggested mud mixture. I mixed a 10%
cement and mud mortar, and it worked just fine. Striking the joint was
actually easier than the store-bought mix.

I now have a lot of CEB out in the rain and I am waiting to see how they
will weather through the winter. I have a few 20% blocks buried and will be
interested to see how they fare next spring. I have been hesitant to commit
to a large project with CEB until I test this material through the winter.

Well, Amanda, this is about all I have time to report. Sorry this message is
so short. I might be able to post some more pictures in the next week or
two. By the way I can't say enough great things about Fernco Metal. They
build a rugged machine. It works well. They constructed mine quickly and it
was delivered right to the barn. And it is the prettiest yellow you could
ask for.

Thanx;
Michael Fitzgerald
Anthropologist/Woodcarver/Puppetmaker

<Snip>
Speed of production on the CEBs has attracted me to them.  There seem to be
two (or three if you can count adobe) basic kinds.  With the first-- blocks
made with a machine like the Cinva Ram, not too expensive (some under
$1000)--do seem to have to cure before you can build.  And making the block
might be a pretty arduous task.  Somebody here's doing it, we'd like a
report!
<Snip>