Researchers at ETH Zurich developed a new robotic additive manufacturing method for circular, low-carbon material, which it hopes can help to make the construction industry more sustainable.
The process has been designed to utilise Earth-based materials that do not require cement, with the construction robots shooting material from above to gradually build structures like walls. On impact, the parts bond together, with only 'very minimal' additive required. Unlike concrete 3D printing, the process does not require any pauses during which the material can solidify.
ETH's Impact Printing method was developed through an interdisciplinary collaboration, with the aim being to increase the cost competitiveness of sustainable building materials through 'efficient and automated production.' In contrast to layer-based 3D printing, this robotic construction method is based on controlled, high-velocity deposition of dense material parts. By depositing material at velocities up to 10 meters per second, the process is said to be able to achieve bonding, with dry joints not considered an issue. According to ETH Zurich, Impact Printing deposits material in a more stable condition compared to typical extrusion-based 3D printing processes, making it less dependent on additives to enhance mechanical strength.
In the development of the technology, a custom printing tool was designed to be integrated on multiple high-payload robotic platforms. This enables the construction process to be realised in offsite production scenarios as well as onsite construction scenarios directly on the building site. The tool has been integrated with a high-payload Gantry system in the Robotic Fabrication Laboratory at ETH Zurich. The hardware can also be mounted on an autonomous legged excavator, developed by the Robotic Systems Lab, and has been used to successfully build structures as tall as 3 metres (nearly 10 feet). The HEAP platform is a legged excavator that has been modified for autonomous operation.
In the future, ETH Zurich researchers believe this could enable the construction process to be deployed directly in unstructured sites with variable terrain to realise wall structures and infrastructure such as acoustic barriers. The robotic additive manufacturing process enables the production of customisable wall and column structures. Novel software and computational design methods were developed to design these structures and control the robotic construction process. While the walls produced using this method have surface texture, but methods for robotic surface finishing methods using ecological plasters can be used to achieve a high-quality surface finish. The additive manufacturing process was specially developed for circular materials with low embodied CO2, such as earth-based and excavated materials. A low environmental impact earth-based mixture has been developed by the Chair of Sustainable Construction at ETH Zurich. This mixture includes several components: primarily locally sourced secondary material with a minimal amount of mineral admixture. Most of the material is sourced locally from by-products from an industry partner, Eberhard Unternehmungen, a leader in circular methods for the building sector.
ETH says the robotic additive manufacturing method could be extended to other materials in the future for other load cases and application scenarios.
