[Cob] RE: lime concrete

[Marlin]

We used the burnt clay as a "pozzolan" to react with the Lime. Together with the sand this Lime/Sand/Burnt Clay turned out to be our mortar of "Roman Concrete". There's a long history of Pozzolans and we're just experimenting with it now....a model we created worked great with a crushed fire brick and we bought fired/powdered clay from a Clay distributer just outside of Madison. It appears to be a good cement but it takes considerably longer to cure (100years to be exact - at least fully) so we had to give the foundation a couple of weeks and we didnt' try building underground where the CO2 can't get to the cement.

The Romans did a great job with volcanic ash added from what I understand. We don't have any volcanoes nearby so burnt Clay (Grog) was the best available....there's some reinterest in this more eco friendly cement and also because of restoration of old building there's more available info.....see :http://www.dirtcheapbuilder.com/, think Charmaine has a book or two specializing in Lime. Cob cottage is bringing some Lime experts from Wales/Scotland I think this year too. Wish I could attend.

Then as usual, go out and try it for yourself, try different amounts of additives, who knows some juice or something might turn out to be the key to making cement that lasts 3000 years, heaven knows our Portland Cement doesnt' have that ability...

BEst,

Marlin


           info at outtathebox.org  
           www.outtathebox.org
"There are solutions to the major problems of our time, some of them even simple. But they require a radical shift in our perceptions, our thinking, and our values."
   - [Fritjof Capra]



-----Original Message-----
From:     Yun Que <yunk88 at hotmail.com>
Sent:     Sat, 29 May 2004 10:09:42 -0400
To:       lightearth at onebox.com; coblist at deatech.com
Subject:  RE: Re: [Cob] cob raised beds?


   Cat here,  what is the burnt clay you speak of?  What does it do for
   the morter and could crushed clay bricks be used?
   for the good of all C.