600 year old Hohokum dwelling made of caliche. Tamped caliche in plastered earthbags would be even more durable.

600 year old Hohokum dwelling made of caliche. Tamped caliche in plastered earthbags would be even more durable.

Certain types of soil for earthbag fill material may be available for free or dirt cheap. Excavation companies typically want to empty their trucks as quickly as possible to reduce labor and trucking costs. Ask them for ‘clean fill dirt,’ which is low cost soil free of debris. It’s best to avoid problem soils such as expansive clays.

One example of low cost soil that’s sometimes available from excavation companies is caliche. Caliche is calcium carbonate or decomposed limestone soil. Its nickname is nature’s cement, and covers about 12% of the earth’s crust. I’m referring to soil with calcium carbonate, not the stone. It’s widely available in Texas. Sometimes caliche is used in adobe, compressed earth block, rammed earth construction, and earthen plaster and floors.

Quentin Wilson, a leading authority on adobe construction, mentions the use of caliche on his website. He recommends a mix of 70% limestone fines, 30% caliche and 3% asphalt emulsion. The asphalt emulsion isn’t needed if you put the mix in earthbags and plaster the walls.

Pliny Fisk of Center for Maximum Potential Building Systems says caliche performs very well when mixed with sand and about one percent Portland cement. They have a demonstration building with walls made of caliche mixed with fly ash and Portland cement to form calcrete. Caliche can reduce the use of Portland cement by two thirds.

The Caliche Report – The Distribution and Use of Caliche as a Building Material: This is the best source I have found on building with caliche. The composition of caliche varies widely and so you’ll want to apply the findings in this report to ensure good results.

Photo credit: http://woodsworth.ca/IMG_1436_edited.JPG


Caliche — 12 Comments

  1. I would like to make a cave below the caliche is it safe to do this. Or can the caliche cave in on me or if I shore/ brace up the walls like they did in the mining days

    • Some caliche is quite solid, while other may be more fragmented…so it depends. I suggest doing some test excavations and evaluate how much shoring up is necessary.

  2. Hi Owen, thanks for the caliche info. I’m a sculptor from Arizona but currently living in Connecticut, meaning I don’t have access to caliche anymore. Do you know how I could “make” caliche in a semi-humid environment (it’s fall here and starting to get cold) or is it as simple as pouring calcium carbonate on dirt/sand and waiting? I’m hoping to recreate, as close as I can, the Tucson ground for a sculpture. I’ve haven’t had much luck finding this kind of information, so any help is appreciated.

    • Owen is out of the loop in answering questions for awhile, so I’ll give you my thoughts about this. Caliche is very similar to limestone; in fact “cal” in Spanish means “lime”, so I would think that you could approximate the look and texture of caliche by making a mixture of hyderated lime with some local soil, dampen it and wait for it to cure for awhile. You could experiment with various proportions.

  3. I would like to build a house on a property. Presently, the ground dirt appears calichey dirt. Is it a good idea to build a house on this type of soil? Should I bring in dirt before I build a slab? what about the septic field lines? How deep should I place them? However, I do need to raise the subgrade where the home would go, about 4 foot. What kind of dirt should I use?

    • There are many types of soil. Talk to an engineer and get a soils test to know for sure. At minimum, talk to an experienced builder in your area who can answer your questions. They will also know your frost depth. Always bury pipe below the frost line as advised in your local codes.

  4. My backyard neighbor increased their elevation by 3 plus feet using pure caliche soil from street excavations in the area. They put up no retainer walls or anything to prevent the caliche from eroding onto my yard. My yard is filled with flowers, plants, trees and bushes. The area that was elevated is 75′ by 50′. What will be if any the consequences to my yard with them elevating their 75 by 50 foot lot by 3 plus feet grade increase.

    • There are laws against this. You’re going to catch their runoff. Talk to a lawyer who does this type of work. Try to settle out of court by having them build a proper retaining wall like they should have to start with.

  5. Hi I hope this gets to you.I live in southwestern texas a we have lots of calichi.my question is can I use only calichi on bags to build.and if not please reply.

    And if I did rammed earth with calichi
    Can it also be solid calichi .being stucco ed at the end tks

    • Search our blog for info on calichi. There’s also a soil building research institute in Texas with in-depth info on building with calichi. I have no firsthand experience with it.

  6. I would like to build some green dome shaped cottages with caliche in the Virgin Islands. they will be completely off grid. I would like to know how best to use caliche [which i have in large amounts] as the main ingredient in a caliche-crete mixture. i would like to use something like a gunnite machine to spray / shoot it ont a form and am looking for ideas as to the mixture needed. i have a local quarry dust and the caliche. sand and cement are very expensive so it is not in the equation. Any Ideas?

  7. From David:

    Pliny Fisk has also used a concrete mix for many years now that uses up to 50% fly ash, greatly reducing the amount of portland required while also sequestering the fly ash content. That should also reduce the costs as well as the environmental impact. He refers to this as “ash-crete” as I recall.

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