Raw earth offers a sustainable alternative as a construction material. This clay mineral-based material has excellent hygrothermal properties, recyclability, a low carbon footprint, minimized transportation needs, and is widely available. Besides primary clay mineral deposits, remnants of aggregate washings and excavated material, which would otherwise end up unused in landfills, can also serve as sources of raw material. Despite its benefits, raw earth has drawbacks such as lower strength, higher erosion sensitivity, and longer drying times compared to conventional construction materials. To address these issues, it is common to stabilize the earth with Portland cement or lime. However, this method only moderately improves the negative properties, while greatly reducing the positive characteristics, such as the low CO2 footprint, hygrothermal properties, and recyclability. A potential more effective approach would be to stabilize raw earth using magnesium-silicate cement, which synergizes better with clay minerals. This method increases the strength to over 12 MPa, reduces initial and final drying times to 7 and 16 hours respectively, and improves water resistance. Additionally, by selecting the right admixtures, this stabilization method is compatible with the poured earth technique. This technique liquefies the material, reducing labor and expanding its range of applications.

Contact:

Raphael Kuhn, Ellina Bernard

Publications:

1)     5th International Conference on Bio-based Building Materials (ICBBM 2023), June 2023: Mg-binders as low carbon stabilization in earth construction, R. Kuhn, P. Lura, G. Habert, E. Bernard

2)     12th ACI/RILEM International Conference on Cementisious Materials and Alternative Binders for Sustainable Concrete (ICCM 2024): June 2024, Comparison of early age properties of MgO and PC stabilized clays containing sodium hexametaphosphate, R. Kuhn, P. Lura, G. Habert, E. Bernard

3)     9th International Conference on Building with Earth (LEHM 2024 ), September 2024: Improvement of clay-based material properties for sustainable construction by the addition of a Mg-based mineral binder R. Kuhn, Y. Du, P. Lura, G. Habert, E. Bernard

Links:

https://data.snf.ch/grants/grant/201697

https://www.empa.ch/web/s308/magnesium-in-earth-materials

https://sc.ibi.ethz.ch/forschung/research-projects/Deciphering-the-role-of-magnesium-in-earth-materials.html

https://www.empa.ch/web/s604/eq80-bauen-mit-lehm

https://sc.ibi.ethz.ch/aktuell/2023/07/EMPA.html

https://www.admin.ch/gov/en/start/documentation/media-releases.msg-id-98063.html

https://www.horizonte-magazin.ch/2023/06/01/die-haeuser-von-morgen-werden-heute-im-labor-entwickelt/