  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. In this paper, two finite element
method (FEM) strategies are presented for simulating such 3D concrete printing
processes. The aim of these models is to predict the structural behaviour
during printing, while the concrete is still fresh, and estimate the optimal
print speed and maximum overhang angle to avoid print failures. Both FE
analyses involve solving multiple static implicit steps where sets of finite
elements are added stepwise until failure. The main difference between the two
methods is in the discretization of the 3D model. The first method uses
voxelization to approximate the 3D shape, while the second approach starts from
defining the toolpath and constructs finite elements by sweeping them along the
path. A case study is presented to evaluate the effectiveness of both
strategies. Both models are in good agreement with each other, and a comparable
structural response is obtained. The model's limitations and future challenges
are also discussed. Ultimately, the paper demonstrates how FEM-based models can
effectively simulate complex prints and could give recommendations with regards
to a better print strategy. These suggestions can be related to the maximum
printing speed and overhang angle, but also the optimal layer height and
thickness, the specific choice of the infill pattern, or by extension the
mixture design. When print failures can be avoided, this methodology could save
time, resources and overall cost. Future work will focus on the validation of
these numerical models and comparing them to experimental data.
