Multiphysics modelling of 3D concrete printing: From material model to process simulation and optimisation

Predictive simulation of 3D concrete printing is important to warrant printability and durability of print pieces and to optimise printing parameters, yet tedious due to the complexity of the material behaviour and printing process. From a constitutive model allowing a continuous description of the coupled chemo-thermo-poro-mechanical behaviour of cement-based materials from the early-age to the hardened state, a comprehensive finite element simulation framework is designed. It aims at modelling extrusion-based 3D printing processes, taking into account the sequential deposition of material. Study of the onset of plastic collapse on specific geometries at different printing speeds show the complexity of collapse prediction as well as the importance of process-related effects. An optimisation scheme is proposed to determine optimal printing speed modulations from numerical simulations with the perspective of increasing productivity in 3D concrete printing. The model shows good predicting capabilities when compared with experimental printing failures, and is able to extrapolate to other accelerator dosages without model re-calibration.