Everything we ever wanted to know about raw earth materials!

The project « Earth Cycle » is making its first steps. After a few months’ preparation, the project officially started on the 1st of March. A first event was held on the 4th of April, which allowed all project partners to share a common knowledge on the fundamentals of the project: the production of raw earth materials.

The creation of a new production chain

Earth Cycle aims at recycling excavated earth at a large scale. The millions of tons of soil excavated in Sevran on the occasion of the construction of the new metro line, the Grand Paris Express, have triggered the idea of a new way of creating value out of what is normally considered as waste. A modular plant set up in Sevran will be producing three types of raw earth building materials, namely bricks, panels of clay and wall coating, starting in 2020.

Up to now, the production of raw earth materials has been exclusively small-scale and handicraft. The innovative value of Earth Cycle lays in the industrialisation of the production process in order to bring about the emergence of a new chain for the construction sector.

The originality and the power of the project also stem from the diversity of the partners who have joined forces to make it succeed. Besides the City of Sevran, who initiated the project with Grand Paris Aménagement, the partnership counts private companies specialised in land management, developers, scientific researchers, architects. Each of the twelve partners will contribute with its skills and knowledge through the different phases of the project, but in order to successfully start, we felt the need to allow all partners to improve their familiarity with raw earth, its qualities and its characteristics.

For this reason, on April 4, more than 40 people gathered in Sevran to participate in a first intensive training session about raw earth materials. A few city representatives joined the technical staff, eager to learn more about this transformation process from waste to building material.

A very sensual relationship to earth

This first training day was meant to be not just practical, but haptic. Romain Anger, Educational and scientific director of amàco, who designed the training session, wanted above all participants to manipulate excavated earth from the Paris region. Through a series of lectures and, more to the point, through practical workshops, the participants could dive in, experiment and explore the knowledge, the know-how and the collective making of the transformation of earth.

A number of disciplines (arts, sciences, engineering, architecture) and a sensorial approach were summoned to show the principles and the potential of earth materials when used in construction.
During the afternoon session, all participants turned into masons and learned how to manufacture wall coating, molded bricks with fibers and rammed earth structures. Making it with your own hands changes everything! The intellectual understanding of the mechanical transformation of matter becomes reality; everyone touches, kneads, smells, adds some water, hesitates, then adds some more… our first hand-made products take shape. We are all proud of our creations and above all, we become aware of the potential of this incredible resource and of its ecological, aesthetical and functional virtues.

A return to the pleasure of touching that city representatives, engineers, developers, researchers and communicators were able to savor throughout the day.

We now know that…

• Cement concrete is nothing but a variation on traditional clay concrete, that is, a mixture of grains held together by a binding agent.
• Excavated earth varies according to two key parameters: its water content and its grain structure. Different soils will result in different materials when transformed. The challenge for Earth Cycle, therefore, is to design the production unit in a way that is suitable to transform the excavated earth found locally, while producing materials that constructors will be interested in buying. The idea here is not to go and look for a specific resource, but rather, to adapt the process to the existing resources.
• The most remarkable quality of earth materials in construction is its capacity to regulate humidity, as clay absorbs excess of water in the air. At the same time, water can become the worst enemy of earth materials: if the materials are not stabilised, for example with lime, the building will need a “hat” and “boots” to be protected from rain and, more important, from capillary ascension from the ground.

There is still a long way to go. Many of the secrets of raw earth are waiting to be unfolded. At the end of this first training day, we all feel a sense of responsibility: we are taking part in the emergence of a new panel of building materials, which may well transform contemporary architecture and places we live in. To be continued…

Author: the EARTH CYCLE project team