Ryan asked a question recently, in the message board, about using Caliche in cob.  I too have a layer of caliche in my soil, about 3 feet down under the ‘adobe dirt’.  Caliche is a form of calcium carbonate that cements together other materials like gravel, sand or clay. It’s generally found 3 to 10 feet under the topsoil in arid or semi-arid regions. The term caliche is Spanish and is originally from the Latin calx, meaning lime.

I wonder if it could be used as a replacement for sand? Pulverized caliche could add color or brightness to your finish plasters; kind of a natural lime or whiting.  I haven’t experimented too much with this material as an additive to cob.  I doubt it would have a negative affect.  Let us know if you have experimented with caliche and cob!

Update:

Thanks to Jim for pointing out The Center for Maximum Potential Building Systems, Caliche Report [PDF]

Geological materials co-mingling into a perfect earthen mixture.  This photo was taken where a fine, light colored sand lays next to adobe clay. It’s delicious to think how these materials are so raw and how somewhere in there mother earth is making a perfect mix!
I’ve used this fine sand mixed with regular adobe dirt, red clay and kaolin clay. Making a variety of different colored alis mixes or earthen paints.

Alis Recipe

60% kaolin clay
40% whiting, sand, and or mica
* Add a cup+ of wheat paste per 5 gallons

I’ve been enjoying the latest newsletter articles by Coenraad Rogmans over at House Alive!. In the article, Building with Sand, Straw and Clay, Coenraad talks about the many variations of the magical mixture of these ingredients. There is a spectrum of ratios that create different variations of these base materials. Including cob, light clay, wattle and daub, bale walls, bale cob, earthen floors, plasters, renders, and paints . Within each application one would use a different ratio for a particular result. Say for instance you are working on a cob wall with built in niches. Ianto Evans teaches about corbel cobs. Cob with long stocks of straw for added tensile strength. Another is light clay, a mixture of straw tossed like a salad with the dressing being clay slip, or watered down clay. Or for an earthen oven a sand clay mixture. You can see how versatile it can be!
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My goodness. It’s so funny I can be this giddy about something like this. My new best friend is the local landfill. I’ve been a fan of dumpster diving for a long time. There are so many things people throw away that don’t need to be ‘filling land’. I wanted a old electric water heater, or at least the metal tube inside, for my SolUnit Rocket Stove so I visited the dump. I wanted permission to look around and permission was granted. “May I re-purpose a old electric heater?” “Go ahead.” said the landfill scale operator. “And the wood pallets?” “Have at it.”

Wow. Junk. Treasures. Resources. Free mulch for landscaping, lumber, pallet wood for building or burning ( most pallets, have 3 good 2×4s in ‘em). Brand new plywood with a few screws in them. I can’t believe what people throw away. Don’t even get me started on the metal pile…

I have been so sick of spending money at stores. Paying a premium for everything, plus tax. Forget it! I can be more resourceful than that. And it’s so much more rewarding. If I ever get bored or just want to be outside, I go pull nails and all of the sudden I have dimensional lumber to use. For free. Happy dumpster diving!

Twigs carefully placed together to create a whimsical space near the bald spot at Carleton College. This sculpture was made with Willow, Buckthorn, and Dogwood harvested in Carleton’s Cowling Arboretum and McKnight Prairie. Artist Patrick Dougherty and Carleton staff, students and volunteers constructed it in October of 2002. On the plaque next to the sculpture it says it will have a expected life-span of two years. Now in 2006, four years later, it’s still standing – though some of the walls are bending over. I like how this space creates a fairy-tale landscape in contrast to the brick and mortar campus.
You can see more pictures at the Twiginometry exhibition » and check out what Patrick is up to at Stickwork.net »