Since 2014 a pavilion made of rammed clay has stood in the listed Steiner Garden at the ETH Hönggerberg. From 19 prefabricated elements, three interlocking arching slabs were formed, which support six vaults, thus creating a small, five-metre-high pavilion.
Collaboration with Gian Salis and clay specialist Martin Rauch led to the development of new ways of building with rammed clay: a statically optimised design combined with the prefabrication of elements makes it possible to build supporting arches from unreinforced rammed clay, which was not previously possible. This required not only that construction processes and tools be developed, but also that testing be performed to verify that the bearing capacity of the elements is not substantially diminished when the ramming stratification deviates greatly from right angles with the line of force, or is even parallel with it.
A sheet metal lining protects the roof from wet weather. Tamped trass limestone layers protect the clay surfaces directly exposed to weather from progressive erosion. In the coming years this pavilion will provide further findings about the stability of clay structures. These results and experience will show whether the advantages of rammed clay can also be used in the long term, such as the reduction of embodied energy, as clay is a local good and does not need to be fired.
2013 to 2014
ETH Zürich Immobilien
Professur Annette Spiro, Doz. Gian Salis und Studenten, ETH Zürich
FUNCTION WITHIN PROJECT
Development and planning of a support structure made of rammed clay vaults and foundation. From concept and experimental verification up to and including execution