Kotrozou, A., Kwang, K.-J., Tahavvori, S., Siriwardena, L., Körner, A., Menges, A., & Knippers, J. (2026). Con(knit)uous Rubble: A Novel Additive Manufacturing Approach for Unprocessed Concrete Rubble. In Proceedings of the 31st International Conference of the Association for Computer-Aided Architectural Design Research in Asia (CAADRIA) 2026 (pp. 235–244).
Abstract
This research proposes an additive manufacturing approach for unprocessed concrete rubble on or off-site as a continuous granular system to reduce post-processing and cement binders. A circular knitting machine end-effector, equipped with a camera and time-of-flight sensors, is used to create a seamless, coarse textile container, incrementally filled with rubble and deposited in a layer-by layer sequence in curvilinear, continuous toolpaths, resembling FDM 3D-printing. Material, fabrication, and design experiments present the possibility for self-supporting, compression-only forms such as columns, arches, and walls. Fabrication experiments showcase the feasibility of the system, achieving overhangs up to 25°, arches with a 1:2 span-to-height ratio. Compression tests showed improved load bearing capacity, attributed to the seamless, knitted container. Deformation due to settlement and layer misalignment is the key system limitation. Image segmentation and toolpath height adaptation were used to monitor the jamming and layer height to improve fabrication quality, but this can be expanded. Future work can explore the impact of weathering, bio-based binders for weatherproofing, as well as digital twin technology to enhance fabrication.
