EARTHEN STRUCTURES 4.0: A reengineered material for a sustainable and green circular construction

Modern construction is a chain of activities, all with a large environmental impact: Soil excavation for the foundation pit. Transportation to a waste field of the excavated material. Transportation to the construction site of the construction material, typically gravel, sand, cement and steel to the construction site along with the formwork (wood or steel). Formwork preparation and progressive construction. In case of replacing an existing structure, we should add the steps related to the demolition process and transportation to a waste-field or waste-recycling center of the demolition waste.The above steps are basic to the construction of a new structure in any part of the world. Each of the steps results in the production of new waste (e.g. excavation and demolition) and the use of new raw and processed construction materials (e.g. concrete and steel). Once the concrete or steel structural skeleton is constructed, more materials and energy are necessary for the regulation of the indoor climate of the building. The feature that makes all the above steps necessary in the construction service phases of a building is the choice of the construction material. Concrete and steel are not directly available at the construction site and need to be manufactured and transported from specific processing units. The result of the exclusive use of these materials in new structures makes the building sector one of the biggest pollutants of the planet and users of energy. To address the undergoing climate crisis, we need to transform the way we design and construct our buildings. Earth is a fully sustainable material that can play a basic role to this endeavor leading towards a circular construction economy. To mention some of its benefits over concrete and steel, earth can be available on the construction site, it does not require any chemical additives (and thus can be dissolved and reused without further process), it regulates indoor climates and it is of low cost. Yet there are social, economic, legal and technical boundaries that undermine the potential of earth as a construction material. From a technical point of view, natural hazards such as earthquakes, has shown that earthen structures are one of the most vulnerable materials.In this proposal, I will place earthen structures in the frontline of a circular and sustainable construction economy by making it a predictable, durable and reliable construction material. I will achieve this by: i) studying the long-term evolution of mechanical properties of earthen materials through large and small-scale laboratory experiments, ii) using structural optimization or earthen structures through form-finding and nonlinear numerical analysis, iii) leveraging automated constructed techniques such 3D printing and assembly of prefabricated elements to build according to the digital twin, and iv) comparing results of load tests on physical specimens with numerical simulations.The reengineering of this historical construction technique can have a great impact in our economies, societies and natural environment: it will address the increasing needs for housing reducing times and costs related with the use and transportation of materials through the in-situ automated excavation and construction; it will lead to a safer construction practice in deprived regions where earth is still the basic construction material; it will be the basis for the development of circular green and sustainable building environments.