Swiss researchers develop robotic additive manufacturing method that uses earth-based materials—and not cement

Researchers at ETH Zurich, a university in Switzerland, have developed a new robotic additive manufacturing method to help make the construction industry more sustainable. Unlike concrete 3D printing, the process does not require cement.

According to a press statement from ETH Zurich, the robotic printing process, called impact printing, uses cheap, abundant, and low-carbon earth-based materials such as clay or excavated earth. Currently, the robotic additive manufacturing method uses a mix of excavated materials, silt, and clay. Most of the custom material is common waste product sourced locally from Eberhard Unternehmungen, a Swiss construction company. In the future, the process could use other materials.

With ETH Zurich’s method, a robot deposits material from above, gradually building a wall. On impact, the pieces of material bond together, with minimal additives. Whereas concrete 3D printing creates layers, ETH Zurich’s method extrudes and drops the material one bit at a time at velocities of up to 10 meters per second. The fast speed allows the material to bond quickly. 

ETH Zurich’s process can build full-scale, freeform structures, including one- or two-story walls and columns. The printing tool has been used to build structures as tall as almost 10 feet. The process results in walls with a bumpy texture, but robotic surface finishing methods can achieve a smoother finish.

The custom printing tool can be integrated with multiple robotic platforms. As a result, the tool can build walls in both offsite facilities and onsite construction projects. At ETH Zurich’s Robotic Fabrication Laboratory, the tool has been integrated with a high-payload gantry system. The hardware can be mounted on an autonomous legged excavator to build walls on sites with variable terrain.

ETH Zurich says it aims to increase the cost competitiveness of sustainable building materials through efficient and automated production.