Product quality and processing of additively manufactured concrete components strongly depend on the flow processes during material extrusion. To control layer deformations and enable purposeful design, numerical analyses with varying process and material parameters were performed to obtain a deeper understanding of flow processes and forces developing in the vicinity of the nozzle using the Lagrangian-based Particle Finite Element Method in association with a Bingham constitutive model. This model was validated by comparing the simulated layer geometries with those obtained from laboratory 3D-printing experiments. Within the investigated parameter range, the forces generated under the extrusion nozzle can be 6 times higher than those induced by self-weight and may cause deformations in substrate layers. Since the distribution of extrusion forces may change substantially under the nozzle for varying parameters, a novel indicator based on the yielding material is introduced to find optimal 3D-printing parameters to prevent plastic deformations in substrate layers.