Exploring 3D Concrete Printing of Lattice Structures on Robotically-Shaped Sand Formwork for Circular Futures

This research bypasses the use of wasteful scaffolding and moulds, by exploring 3D concrete printing (3DCP) on reusable sand-based substructures. Non-standard, complex geometries generally require the use of formwork to be produced, leading to wasteful, material-intense manufacturing processes. The research explores optimised material depositing strategies for 3DCP on robotically shaped sand formwork. The need for timber scaffolding, plastic or foam-based moulding for casting concrete is avoided. The fabricated structures are lattice-based lenses with varying curve densities, envisioned as screens part of facade systems and spatial dividers. The research addresses the need for circular construction, reduction of raw-material usage for concrete formwork and the development of optimised material depositing strategies to undercut concrete usage. The deployed method falls under the category of sub-additive concrete printing. Firstly, the sand-based formwork for printing is shaped robotically through the use of different customised end-effectors. The robotic sand-forming of the substructure can be repeated multiple times, as almost no material loss is encountered. Subsequently, the robot arm is used for 3DCP along a three-dimensional tool path on the robotically shaped sand formwork. Parameters such as extrusion flow, printing speed and angle were tested and optimised to guarantee high-precision printing and resolution.