Influence of Printing Speed and Nozzle Size on Buildability of 3D Printed Concrete Walls (2025-10)¶

The increasing adoption of additive manufacturing in construction necessitates robust simulation frameworks capable of capturing the time-dependent mechanical behaviour of fresh concrete. This study examines the influence of printing speed and nozzle size on the buildability of infilled concrete walls using finite element (FE) simulations. A nonlinear fracture-plastic constitutive model was employed to simulate the time-dependent mechanical behaviour of fresh concrete, with the modelling framework first validated against previously published experimental data to ensure reliability. Subsequently, six wall configurations were analysed, incorporating nozzle diameters of 30 mm and 40 mm, and printing speeds of 20, 30, and 40 mm/s. The results demonstrate that printing speed exerts a dominant influence on buildability. At the highest simulated speed (40 mm/s), premature structural failure was observed, limiting maximum wall heights to 0.56 m for the 30 mm nozzle and to 0.50 m for the 40 mm nozzle. At the intermediate speed (30 mm/s), structural stability improved markedly, with wall heights of 1.16 m and 1.12 m achieved for the 30 mm and 40 mm nozzles, respectively. At the lowest speed (20 mm/s), both wall models successfully reached the full target height of 3 m without collapse, and displacements remained minimal. While nozzle size had a less pronounced effect overall, it was found that the larger nozzle (40 mm) exhibited earlier collapse at higher speeds due to increased self-weight.