custom robot by gramazio kohler builds undulating rotunda with 30,000 soft clay bricks

exploring a new robotic method of space-making, zürich-based gramazio kohler research unveils a sculptural clay rotunda. the free-standing earth-based cylindrical structure is realized within the SE musiclab, a high-fidelity music auditorium built inside the newly refurbished gurten brewery in bern, switzerland. the project stands as a combination of zero-waste, sustainable clay and computational design methods. featuring a diameter of nearly 36 feet (11 meters), the rotunda reaches a height of over 16 feet (5 meters) with just 6 inches (15 centimeters) of unreinforced clay. the project was constructed on site by a mobile robotic system that aggregated over 30,000 soft clay bricks over a period of 50 days.

images courtesy of gramazio kohler research

gramazio kohler research builds its clay rotunda as an extremely slender surface made possible by its undulated design. the curving plan allows for an increased footprint and stabilized structure, preventing buckling. the geometry of the this shell is controlled by a computational model that considers the structural models of the engineers, the material properties of the clay, and the sequencing of the building process. the team notes that the limited reach of the robotic arm and the shrinking of the material while drying had called for complex strategies for the segmentation of the shell into matching trapezoids.

key for the performance of the structure, gramazio kohler research designs its clay rotunda with a highly optimized material system. different compositions of clay, sand, small stones, and water were tested to find the best balance of malleability and compressive strength, while minimizing material shrinkage. the developed clay mix is extruded into ‘soft bricks,’ or cylinders with a diameter of 3.5 inches (9 centimeters) and a height of 6 inches (15 centimeters), which are grabbed by the robotic arm from a picking station, precisely oriented, and sequentially pressed into their final position — compressed to about 60% their original height.

the compression of the clay bricks leads to a soft bond that expresses both the material plasticity and the dynamic forces of the fabrication process. gramazio kohler research’s custom robot — the in-situ fabricator — was repositioned for every single segment to address the full scale of the structure. this relocation of the robot as well as the deformation of the fresh material caused by its shrinkage required a regular acquisition of the as-built geometry through 3D scanning. the drying process resulted in unavoidable cracks that were actively monitored and regularly filled with the same clay mix.

with its clay rotunda, gramazio kohler research addresses the urgent need of reducing material consumption. further, the team notes a need to revert to emission-free materials in construction. the robotic clay aggregation process combines the traditional knowledge of clay constructions with contemporary digital design and fabrication processes. the increased degree of control on both material and process allows building complex structures that go beyond what has traditionally been possible. clay also has excellent properties in regulating the interior climate of buildings, thus reducing the need for mechanical ventilation and creating comfort for all inhabitants. finally, earthen constructions are entirely waste-free, since the used clay mix can be ground and fully reused. what is taken from nature can be returned entirely to nature.

project info:

project title: clay rotunda

author: gramazio kohler research

location: SE musiclab, bern, switzerland

client: SE musiclab AG — jürgen strauss, jost kutter, manuel frick, lorenzo zanetta, filippo melena, anna imfeld-aebischer, markus imfeld

collaborators: coralie ming (project lead), david jenny, hannes mayer, edurne morales, anton johansson, indra santosa, jomana baddad, nicolas feihl, selen ercan jenny, jesus medina, karol wojtas

support: mike lyrenmann and philippe fleischmann (robotic fabrication laboratory, ETH zurich), andi reusser (institute for building materials, ETH zurich)

selected experts: seforb sàrl — joerg habenberger, gotham design studio

selected contractors: LEHMAG AG — felix hilgert

industry partner: brauchli ziegelei AG, wirz AG bauunternehmung

sponsors: wirz AG bauunternehmung, welti furrer, eberhard, siemens, geberit, ETH zürich foundation

completion: 2021