3D Concrete printing and circularity : designing, testing, and modelling dry joints for structural applications.

The technology of 3D concrete printing (3DCP) is advertised to reduce the total amount of concrete used in construction, through selective placement of material following principles of structural design and optimization. This has led to a rapid increase of 3D printed applications in practice, such as bridges and low-rise buildings [1]. The vast majority of these projects, however, consist of structures produced in a monolithic manner: a large 3D printer produces the entire object in one go. This de-sign strategy renders disassembly and reuse near impossible, and thus, does not com-ply with principles of a circular economy in construction. When objects are produced in parts, e.g., in a ‘prefab’ printing environment, the absence of dry joining principles for 3DCP results in glued or cast-in-place connections when assembling the final structure [2]. This, again, limits reusability. To support the transition of the construc-tion industry towards circularity, this contribution presents the design considerations, experimental testing, and numerical modelling of dry joints for 3DCP.