You take clay-containing earth, such as excavated from a construction site, mix it with water and Oxacrete © and pour the mixture into a formwork. After one or two days you get sustainable seating elements - without the addition of cement. These are being tested by the SBB in mobility sharing zones near the train station, created in the Innovation Park.
Founded in October 2019, the ETH spin-off Oxara has made this possible, with the vision of providing access to sustainable and inexpensive building materials. Central to the Oxara technology is the mineral additive Oxacrete ©, which provides a way of building with earth as if it were concrete, but without the addition of cement. Excavated material is converted into a sustainable building material and can be reused, closing a circle in the construction industry.
The first prototypes created in the hangars of the Innovation Park
Oxara is producing seating elements for the SBB in the Innovation Park in Dübendorf. These will be tested in future in mobility sharing zones near the train station. Oxara has enough space available in the halls of the Innovation Park to produce twelve prototypes from mid-August to the end of September 2021. They are produced as follows: First the formwork is put together and filled, then, after early strength is reached, the elements are stripped out again and dried. The surfaces are then processed and assembled. Oxara carries out all of these steps on the grounds of the Innovation Park. The required Cleancrete © soil mix is mixed at a Kibag plant and then driven onto the site by mixer truck, where the mix is poured directly.
Earth as a cheap and sustainable raw material
Earth has been used successfully as a raw material for building in many regions of the world for a long time. In contrast to most conventional building materials, earth is available everywhere, causes practically no CO2 emissions and is inexpensive.
Oxara is now addressing the question of which building components cast earth is also suitable for in Switzerland. Although not always visible, traditional ways of building with clay were also used in Switzerland. The techniques used, such as rammed clay or cob walling are labor-intensive and therefore expensive. Oxara's earth concrete is therefore designed to use the same installations as used to make concrete, bringing new access to the earth material.