A Short History of Rammed Earth

From the earliest times the only way for humans to build shelter was to use locally available raw materials. Rammed earth is estimated to have been used since around 5,000 B.C., often enclosing a wooden framework with a mixture of raw earth combined with plant fiber. Thin wooden sticks can be driven into the ground or attached to the foundation and tied to thinner horizontal pieces of wood, creating a grid pattern onto which the earth is applied on both sides.

Hand-rammed earth (constructive elements) © Paulo Cesar Menezes, via Wikimedia Common

A Brazilian technique emerged through the combination of methods employed by Portuguese colonizers and enslaved African populations. It was often used for the interior walls of larger houses due to its lighter weight and in the construction of slave quarters, reinforcing the social hierarchy through architecture. Hand-rammed earth became associated with a more humble and temporary type of construction.

Hand-rammed earth house © Dante Laurini Jr via Wikimedia Commons

A living example of a traditional Brazilian type of construction is the process of treading the earth to achieve the necessary malleable texture for placing and adhesion on the wooden structure. This was commonly accompanied by singing while the dance followed the rhythm of the footsteps.

Detail of the earth piling process © Moshirah via Wikimedia Commons

Another system that was already in use around 4,000 B.C. in the Mesopotamian region involves compacting earth within wooden forms in layers of approximately 15 centimeters (6 inches). The form is placed on the ground or foundation (commonly a continuous footing), and the earth is placed inside and rammed. Once compacted, a new layer of earth is added on top of the previous one, and the process is repeated until about 2/3 of the form is filled. Then, the form is dismantled and repositioned on the constructed wall, and the sequence begins again until the desired height is reached.

An earth wall at the Nk’Mip Desert Cultural Center. Image © Nic Lehoux Photography

In Brazil, the rammed earth with a mold construction system was brought by the Portuguese. The structures had rectangular floor plans with central rooms and porches. This technique was widely used in São Paulo from the 17th to the 19th centuries.

Detail of construction in hand-rammed earth © Luis Bartolomé Marcos, via Wikimedia Commons

Both hand-rammed earth and rammed earth with a mold represent traditional systems and embody the so-called “popular knowledge”  in construction. This does not mean they are the best solution for every context: their structural performance falls short in terms of tensile strength, and the walls should not be in direct contact with the ground or moisture. Like any construction system, this requires specific care.

Kalì Pavilion / Irene Librando e Nadia Peruggi © Irene Librando, Nadia Peruggi, Lucile Bitz, Antonella Mennella

Adopting these systems brings the possibility of building without transporting foreign materials to the construction site since the raw material comes from the local environment. On-site preparation is also an advantage as it does not require specialized labor, making the situation similar to an experimental construction site. It becomes part of daily life, a hands-on form of know-how.

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