Hollow Ceramic Components via Multi-Material Co-Extrusion 3D Printing

Additive manufacturing (AM) enables the production of customizable and geometrically complex building components. When applied to ceramics, a fundamental building material with exceptional durability, moisture regulation, and thermal stability, AM can further enhance functional performance through geometrical design. Despite these advantages, ceramic AM remains challenging to scale up for building applications due to low deposition rates, limiting its application. This research investigates the feasibility of applying a co-extrusion Direct Ink Writing (DIW) workflow for scaling up hollow ceramic structures for architectural components. In this study, a co-extrusion set-up was developed to extrude larger bead profiles combining inorganic clay with an organic infill, enabling faster layer build-up to reduce fabrication time while leveraging the intrinsic firing process to produce hollow, lightweight components. A first set of print experiments studied a variety of bead profiles extruded using different nozzle attachments and extrusion parameters, demonstrating the possibility of co-extrusion with a total extrusion width of up to 12 mm and achieving resultant shell thicknesses down to 1.5 mm. A second set of experiments produced brick-scale components, where a comparison between solid and hollow components showed both a reduction in print time of up to 27% while simultaneously producing lighter components with up to 28% mass reduction after firing. This study demonstrates the 3D printing and firing of hollow ceramic structures at an architectural component scale, while evaluating the potential benefits of reducing printing time, component mass, and material usage compared with standard ceramic DIW. Overall, this study supports the advancement of ceramic DIW by addressing fabrication efficiency limitations at the building application scale.