The historical journey of construction also tells the story of humanity. The enduring examples from the past reveal insights into their specific contexts, and the remnants that have survived the elements and decay narrate the development of human technology. In the early days of construction, the common (and often the only) practice available to humans was to use locally available raw materials. For many, this meant building with clay.
Since the development of more durable construction techniques and resistant materials allowing for varied formal compositions, building with earth has become more associated with traditional, historical, ecological, or social contexts, particularly in rural settings. In any case, in Brazil, earthen construction systems date back to colonization and the resulting cultural blending. The construction process using rammed earth is one of the most well-known and can be considered to have two variations: hand-rammed earth or rammed earth with a mold.
Hand-Rammed Earth
This construction system, estimated to have been used since around 5,000 B.C., involves enclosing a wooden framework with a mixture of raw earth (meaning without firing) combined with straw or plant material. Thin wooden sticks can be driven into the ground or attached to the foundation and tied to thinner horizontal roundwood, creating a grid pattern onto which the earth is applied on both sides.
The 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, and consequently, it was overlooked in the lineup of "grand" Brazilian architecture examples.
However, this technique encompasses significant concepts in the required shift of attitude within the discipline. It remains a living example of a traditional Brazilian type of construction, unfolding into collective practices that shape intangible heritage, such as dance. The process of treading the earth to achieve the necessary malleable texture for adhesion and handling on the wooden structure, in some regions, was commonly accompanied by singing while the dance followed the rhythm of the footsteps. The "coco" dance can be understood as a gestural transposition, an invisible architecture. This type of relationship is intriguing because it touches upon the boundaries (or lack thereof) of the discipline as a whole.
Hand-rammed earth is also stigmatized due to its association with Chagas disease, caused by the protozoan Trypanosoma cruzi. While the construction can harbor disease vectors, such as the kissing bug, insect transmission results from disturbances and imbalances in the ecosystem to which the vectors belong. Insects seeking refuge in buildings is a consequence of alterations in their natural habitat and a reduction in predator populations. Constructions need to be properly sealed, which can be achieved, for example, with earthen mortar. Public policies should also consider self-construction systems, allowing traditional and popular knowledge to benefit from investments and technical improvements, thus continuing the construction history.
Rammed Earth With a Mold
This system was already in use around 4,000 B.C. in the Mesopotamian region. The process involves compacting earth within wooden forms in layers of approximately 15 centimeters. 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.
In Brazil, the rammed earth with a mold construction system was brought by the Portuguese. Strongly linked to the regions of Goiás and São Paulo, where the availability of stones was limited, this technique became somewhat associated with the Bandeirantes. The structures had rectangular floor plans with central rooms and porches. This specific feature led Luís Saia to propose that these houses were influenced by the villas of Andrea Palladio. In this context, it is not entirely surprising that Brazilian architecture entered a neoclassical phase.
The rammed earth with a mold construction technique was widely used in São Paulo from the 17th to the 19th centuries. Its historical and heritage significance was preserved by the former Service of Historical and Artistic Heritage (now IPHAN) in the 20th century, thanks to the involvement of individuals such as Mário de Andrade, the previously mentioned Luís Saia, Rodrigo M. F. de Andrade, and Lucio Costa. The Morumbi Chapel in São Paulo is one notable example of this construction process. Originally part of the Morumbi Farm, the remaining ruins of a rammed earth structure were restored and supplemented with brick masonry by the architect Gregori Warchavchik. He interpreted them as having a religious purpose.
This approach to the project significantly influences the outcome: Warchavchik preserves the colonial architectural language of the remaining structure, echoing relevant examples from this architectural period, such as churches, but employs the construction system of his own time without deviating from the raw material: earth blocks. The Morumbi Chapel is part of the City Museum of São Paulo.
Both cases are examples of historical Brazilian construction and equally deserving of heritage protection. Both hand-rammed earth and rammed earth with a mold represent traditional systems and embody the so-called "popular knowledge," which is certainly more flexible than technical-scientific knowledge, especially 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. In other words, like any construction system, taipas require specific care. 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 and explicit form of know-how.
