People have been making sun-dried clay bricks, or adobes, for millennia. Clay soil is usually mixed with sand, water, and straw. This mixture is then pressed into forms to make bricks. When dry, the bricks are stacked with clay/sand mortar in between to make walls and even domed or vaulted roofs. The ubiquity of suitable materials and the simplicity of production and assembly have made adobe a popular building system worldwide. Considered one of the oldest man-made uniform building materials, adobe has gone through many evolutions during its long history.

In California, as in many areas of the world, there are adobe buildings from the 1700’s that are still standing. Although there is good reason to be concerned about the use of adobe in earthquake-prone regions, recent engineering innovations have improved the safety factor to the point where adobe can be a good solution almost anywhere. We have been involved with reengineering and rehabilitating historical adobe structures to be more seismically resistant.

Aid organizations around the world have been working for decades to improve the durability and resilience of adobe structures. In the 1950’s, earth building took a huge step forward with the invention of the CEB or compressed earth block. Simple human-powered machines use leverage to compress clay soil into blocks with more uniform size and shape and greater compressive strength than traditional adobes. Invented by Raul Ramirez in Bogotá, Columbia, the press was designed to improve the performance and acceptance of earth building materials. It is sometimes used in combination with chemical stabilizers such as asphalt or Portland cement.