Rammed earth is an ancient construction technique similar to adobe that uses the raw materials of the Earth to form sturdy buildings through a simple process. Rammed earth has been around for thousands of years -- portions of the Great Wall of China were constructed using the rammed-earth technique. Today, the process of forming a rammed-earth structure isn't so different than it was centuries ago. A moist mixture of earth and hard substances such as clay or gravel are combined with a stabilizing element like concrete and compressed to form dense, hard walls. After forming, rammed earth must cure for months -- or as long as two years -- in a humid climate to fully cure and completely harden [source: USC].
The density of rammed earth makes it an ideal material for regulating the temperature of a building. It will stay cool in the summer and warm in the winter, and constructing rammed earth produces fewer emissions than the typical building process [source: USC]. Modern rammed-earth equipment makes the compacting process a bit easier than it was thousands of years ago, but there are still tools out there specially designed to compress the walls by hand.
Rammed-earth construction isn't exactly the norm for the 21st century, but it still exists, and there are contractors out there who specialize in designing homes with the Earth's minerals. Rammed-earth construction does have to take special care to properly regulate water to prevent damage, which is much like our next green technology, a system designed to harness water runoff.