What if You Don’t Have Any Clay?

We received the following tip from Birgit in Tanzania, where no clay is available. Thanks for sharing. As you probably know, clay is typically used in earthbags as a binder. Clay is available in most areas, but not where Birgit lives. Birgit’s solution is to “use what’s locally available and affordable: 40% volcanic dust (which is the “earth” I live on), 40% murram (don’t know if this is an international term, but it is a coarse rough gravel type stuff of volcanic origin mainly used for roads) and 20% lime (to stabilize, which is 1/4 of the price of cement and binds well with volcanic matter).”

Birgit reports, “I only finished the wall, but so far this mix seems very successful – a great alternative to areas that don’t have clay. I have kept one bag aside and will ‘take it apart’ soon to see how the mix holds together without the bag. My next project will be a one-room work shop, after which I should have enough experience to dare build a small house – and then we’ll see where it goes.”

3 thoughts on “What if You Don’t Have Any Clay?”

  1. looking to buy property in Arizona. Ground looks sandy large rocks. the well report states volcanic tuff for the first 40 feet, followed by fractured basalt then red basalt… the more i read about what should be in the bags, the more disappointed i am getting.

    • Although sandy soil is not ideal for earthbag building, it can be used. I would not attempt a dome or vault with loose soil, but vertical walls, especially curved ones, can be quite secure. Also, if you can access some of the volcanic soil, then that might work as well. I built an entire earthbag house out of crushed volcanic scoria in Crestone (see http://earthbagbuilding.com/projects/hart.htm ) and it has the advantage of being an insulating material as well.


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