Rammed earth construction has been around for a very long time. It simply involves mixing some dirt with a little water, then pounding the dirt into a form. It is a little more complicated than that, but not a whole lot. The dirt has to be the right mixture of sand and clay. In my son’s case their soil contains a lot of clay. Therefore, they are mixing equal parts fine gravel with their native clay soil. After some experimentation they determined that 3 shovels of gravel and 3 shovels of their clay soil, mixed with a little less than a quart of portland cement and about a half gallon of water, produced a mixture with the right consistency. The cement serves as a stabilizer and makes the wall more resistant to moisture.
|John Tunnell screening the native clay soil to remove clods, sticks, roots, etc|
|My son, James, working at the top of the form, added the mixture and tamped it into place|
They poured a very stout foundation for the cabin, 18 inches thick. I’m not sure how deep the foundation is. There are 3 foot long pieces of rebar sticking out of rhe foundation to help secure
The wall to the foundation. In addition, they are also planning to add a concrete cap to the top of the wall, intended to help bind the wall sections together.
|The pile of fine gravel|
|The pile of sifted clay soil|
|Bags of portland cement|
|A completed section of wall|
|Tunnell family picture on the scaffolding|