Team Blog Series: Rammed Earth Architecture - Mariam Gongladze

The Team Blog Series is a collection of blogs written by members of our team. Each blog's author will tell you about a topic, news, or issue that piques their interest.

Today’s blog was brought to you by Mariam Gongladze, our junior architect. She will introduce rammed earth architecture, its history, and very interesting examples.
With evidence of its use extending back to the 9th–7th millennium BC, Neolithic Age-Earth architecture is a unique and ancient construction technique utilized in traditional and vernacular architecture. Because of its inherent sustainability, rammed earth has been utilized by man for thousands of years and is presently seeing a revival in several regions of the world. With time, different techniques evolved, starting from sundried adobe blocks to cob constructions, rammed earth walls, and compressed earth bricks. Building with earth is regaining some interest as it is regarded as an environmentally friendly option due to its low carbon footprint, low thermal conductivity, and good hygroscopic features.
Ksar of Ait-Ben-Haddou (Morocco) © Yvon Fruneau

Among the oldest structures of rammed earth architecture, the remaining sections of the Great Wall of China, located in Shandong Province, date back to 2500 years. In addition, the oldest examples of earth architecture are found in Yemen and Morocco, where rammed earth buildings in densely packed and populated residential areas date back to the 8th century.
In the Medieval period (13th to 17th centuries), the earth was used throughout Central Europe as an infill in timber-framed buildings and to cover straw roofs to make them fire-resistant. In France, the rammed earth technique, called Terre pisé, was widespread from the 15th to the 19th centuries. Near the city of Lyon, L’Isle d’Abeau – “village de la terre,” several buildings are more than 300 years old and still inhabited. 
Casa em Cunha | Arquipélago Arquitetos | 2019

The Material Composition
Rammed earth technology is a foundation, floor, and wall construction technique that uses raw materials and types of land that compose the soil, such as lime, gravel, clay, sand, and water. The material’s exact composition and component ratios will fluctuate depending on the specific project area and laboratory studies. Therefore, creating a unique earth mixture is needed to use this material for construction. This has the advantage since the components are available all over the world. Loam and gravel are readily available, and other aggregates, such as igneous rocks, marble chips, or marl, can be added depending not only on their availability but also on the purpose and requirements of the job. The challenge lies in developing an appropriate combination.
In order to give rammed earth more excellent resistance to atmospheric influence, the wall surface is often treated with plaster, bitumen, or linseed oil. Stabilizers can be added to the soil to increase weather resistance and strength; Portland cement, bitumen, fibers (natural or synthetic), and natural products are commonly used.
In contrast to other building materials, like concrete, there are no standardized formulas. Accordingly, the properties of each rammed earth mixture vary. Ensuring the suitability of the mix and finding the correct procedure to meet the design requirements depend on the expertise of an earth-building specialist.

Technology
The construction of a rammed earth element can be done according to two methods. First, the construction process is divided into the following phases:
  1. A mixture of damp earth (from 5% to 12% of water) containing: aggregates, sand, silt, and clay is poured into formwork to form a homogeneous layer;
  2. The first layer is then beaten and compacted manually or using a pneumatic piston;
  3. The compacted surface is scraped to offer better cohesion with the next layer to be poured;
  4. The previous procedure is repeated two or three times until the septum height is appropriate and the framework is full.
  5. The reinforcement or framework is removed, and the earth construction is ready. 
In the second, the prefabricated construction process consists of the following phases: In the factory, prefabricated formworks are prepared with a standard size. The pouring and beating process is almost entirely automated. An operator presses again on the ground already beaten by the machine to check that there have been no badly beaten parts. The process is repeated until the production of prefabricated earth blocks of variable shapes and sizes. The prefabricated blocks are transported to the construction site and installed.




Chapel Of Reconciliation | Martin Rauch | 2001

Main Material Characteristics and Advantages:

Structure and Durability
Depending on the structure's height or building, rammed earth does not require reinforcement due to its mechanical properties. Earth is fire-resistant; it does not burn. Different design strategies without additives can be used to calculate and manage the erosion of exposed earth surfaces. Earth is a versatile and flexible material, enabling multiple architectural design forms and options.

Sustainability and Energy Efficiency
Building with rammed earth construction is sustainable and has a minimal environmental impact, primarily when the material can be obtained from the surroundings of the project area. By avoiding cement and lime as stabilizers, the construction becomes even more sustainable and ecologically friendly.

In addition, earth is a globally accessible, bio-based, and utterly reusable material resource that can be transformed to its original form/raw material indefinitely (If the material is unbaked and without added cement.)

Economical Aspects
If the right location is selected, rammed earth is one of the most budget-friendly local materials since it eliminates the need for additional thermal insulation or waterproofing - as the material itself is characterized by those properties, as well as transportation costs for other building materials.

Thermal Abilities
Rammed earth has high thermal mass, which contributes to thermal storage and balancing temperature fluctuations keeping it cool in summer and warm in winter. Heat moves slowly between the rammed earth’s surface and the interior, matching the daily heating and cooling cycle. The clay in the rammed earth elements creates a healthy indoor climate by regulating the humidity, absorbing and releasing moisture into space.

Climate and Context
Working with rammed earth architecture demands a thorough understanding of the climate and site where the building will be constructed. The rammed earth method typically performs best in environments with high humidity and relatively mild temperatures. Rammed earth walls may require additional insulators in colder regions and additional rain protection in areas with high rainfall.
Vineyard House | Blaanc | 2015

Considering the examples of earth architecture, Martin Rauch is one of the most influential figures on the list. Rauch discovered clay architecture through his tendency towards applied craftsmanship and other artistic interests. One of the technological projects of Rauch, as one of the founders of rammed earth technology of modern architecture, is a residential house - Haus Rauch, located in Schlein, Austria. The house is a testament to high-design with low-tech material solutions. This house resolutely establishes that raw earth buildings can hold their own within our industrialized built fabric. Haus Rauch provides the prevailing precedent for those who seek to practice this particular vernacular method within the contemporary building culture. Additionally, his main goal was to emphasize the monolithic block as an essential element of the landscape and environment.
Haus Rauch | Martin Rauch | 2001

Arizona’s own desert environment contributed as the design inspiration for another example of contextualized earth architecture close to one of the state’s deserts. The architects made an effort to create a structure with minimal environmental impact. Therefore, it was not a coincidence that rammed earth architecture was selected. The building’s clean lines and aesthetic of rammed earth allow it to fit into the surrounding Arizona terrain as intended by its creators.
Tucson Mountain Retreat | DUST | 2012

The home is primarily made of Rammed Earth, as a part of vernacular architecture - a material that uses widely available soil, provides desirable thermal mass, and has virtually no adverse environmental side effects. The house was meticulously positioned to optimize sun exposure without excessive solar heat gain and to allow for uninterrupted 360-degree views. The initial decision to use rammed earth played a crucial role in simplifying the design process and construction of the property.

Mexican architect Tatiana Bilbao used rammed earth technology in one of her most budget-friendly residential projects, located on the shores of a lake in the state of Jalisco, Mexico. The materials of the building volumes are considered a contrast of transparent and opaque, reflective and shining through. The texture of the walls, which is characterized by a combination of different warm earth colors, is directly related to the aesthetics of the environment in the project area.
Ajijic House | Tatiana Bilbao |  2010

All of the examples emphasize the reliability and strength of the earth's structures and the possibility of using and adapting the natural resources in different climatic zones. The timelessness of this material promises its use will extend far beyond our contemporary context, but the forms by which it will endure are yet to be seen.

Sources: 
- Sauer, M. Martin Rauch Refined Earth Construction & Design with Rammed Earth. DETAIL Edition. 2015
- Minke, G. Building with Earth: Design and Technology of a Sustainable Architecture. Basel: Birkhäuser. 2013
- Matsdotter, V. Down To Earth. Circular Material Flows // Resource Salvation. Architecture and Planning Beyond Sustainability. Gothenburg, Sweden. 2020
- Peren, I. La tierra cruda como material de construcción: evolución de una técnica. “El caso de Martin Rauch”. Escuela de Ingeniería y Arquitectura. 2019
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