Rammed Earth, nothing but dirt, pounded into forms to create walls. Sounds pretty simple, but there’s a science behind it. Using a properly proportioned mixture of sand, gravel, and clay, with maybe a little binder thrown in for durability. All you need is a form, usually constructed of panels of wood, that can be set up and torn down easily. Most often design to be reusable, these forms will allow you to pour in the dirt, and start pounding. A jack hammer style packer would be perfect. As you build up the material, continual packing is required to insure a dense concentrated material that will retain it’s shape when the forms are removed.
After compacting the soil mixture, the forms can be immediately removed. The curing process for these walls will take up to two years, as they continue to harden, and become stronger. Once fully cured, the walls will be as solid, and hard as rock. Back in history the binder may have been lime, or even animal blood, but today, cement is most commonly used.
Hardening starts quite rapidly when the forms are removed. If a texture is desired the surface can be brushed, but be fast, as the surface will harden beyond that stage within an hour.
Having similar thermal qualities to adobe, Rammed Earth homes will retain the heat of the day, providing an even comfortable temperature at night, while not allowing the heat of the day to penetrate immediately. Thus maintaining cooler inside temperatures during the hottest part of the day.
During construction different types of oxide are sometimes added to give a variety in colors, or interesting wave patterns in the walls. The structure can be a post and beam building with rammed earth filler panels. Though this isn’t necessary as the walls will have plenty of strength on their own very quickly, and can carry the load of a roof easily.
A building that is constructed of rammed earth will also be practically sound proof with the thick, dense material. Being virtually fireproof is another solid reason to make use of this technology. Rammed Earth is considered very ecologically friendly, odds are you won’t have to go far to find the main material required to build a such a structure, dirt is found almost everywhere.
Speed of construction is better then most projects. With reusable forms, and mechanical compacters, a small crew can construct a 2,000 sq ft house in 2-3 days. With building material exceptionally cost effective, and the labor time required, the cost of a rammed earth home becomes very reasonable. Usually no more then two thirds the cost of conventional construction. Better yet, when your done you have a home that can’t be penetrated by termites.
Rammed earth walls are usually 12-14 inches thick. With colored stucco you can have your home in any color, though the natural color of earth is nice, especially once you’ve applied a sealer as a top coat.
A more detailed history of Rammed Earth building can be found at Wikipedia including information about a low cost community that was built in 1936 in Alabama as a further study of Ramed Earth construction.