Strategies for numerical simulation of 3D concrete printing : voxel-based versus extrusion-based meshing

Three-dimensional concrete printing (3DCP) has gained a lot of popularity in recent years. According to many, 3DCP is set to revolutionize the construction industry: yielding unparalleled aesthetics, better quality control, lower cost, and a reduction of the construction time. Nevertheless, many unknowns about 3DCP in the manufacturing stage still remain, such as the maximum number of printed layers before failure or the maximum speed at which a certain design can be properly printed. Previous research studies have shown that numerical simulation of 3D concrete printing can accurately predict the mechanical behaviour of freshly printed concrete and estimate when and how failure might occur. It is expected that these kinds of simulations will become standard practise in the design of digitally manufactured concrete structures. Although standard meshing algorithms work well when conventional designs are being simulated, 3D concrete printing also allows for the creation of very complex parts. In that case, constructing the finite element mesh is much more tedious, taking into consideration the layer-wise activation, contact-based properties, etc. In this work, two distinct meshing strategies are reviewed: a voxel-based and an extrusion-based approach. Their advantages and challenges are thoroughly discussed and compared. Further, we address some issues related to both strategies based on a very complex case study geometry. The results are helpful for further extensions of the voxel-based and extrusion-based simulation strategies.