Investigation of digitally produced, interlocking concrete blocks for a modular slab construction

3D concrete printing has the potential to improve the cost, material efficiency and construction time. Combining the advantages of 3D concrete printing with modular construction enables the principle of topological interlocking of three-dimensional (non-convex) blocks without the use of binding materials. These interlocking blocks can be used in producing deconstructable slab or bridge structures through prestressing. The resulting structures exhibit high rigidity, which gives them considerable resistance to vibrations and crack propagation with 55% material savings. In this study, the mathematical generation of the design of these interlocking blocks is first discussed, followed by their validation using a 3D concrete printing process. The interlocking property and the 3D-printing technique both share the focus on the boundary as a material design concept. For interlocking purposes, the contact surfaces of two neighbouring blocks are essential which has to be part of the path finding algorithm. Several different blocks were printed and the variety of combinations tested. A suitable design was selected for mass production. High accuracy is essential to assemble the blocks into a slab system. In order to guarantee the interlocking property from the printed blocks, a custom path for 3D-printing is proposed. Furthermore, the accuracy in the resolution of printed blocks is ensured by continuous monitoring of the printing parameters followed by 3D scanning after printing. A 4 m long pre-stressed slab will be prepared by assembling the printed blocks of required design and accuracy. The slab will then be loaded to understand the deformation of the individual printed blocks and the overall slab. The data will be used to analyse the requirement of additional reinforcement. The method of in-line reinforcing of printed layers will be utilised accordingly.