Extrusion nozzle design and print parameter selections for 3D concrete printing

3D concrete printing is a rapidly emerging technology. This study presents theoretical formulations for concrete extrusion resistance as a function of nozzle parameters. Results show that the extrusion resistances are related to the extrusion velocity of concrete and the cone angle and length of the nozzle. Lowering the extrusion velocity and nozzle length can reduce the extrusion resistance in the nozzle. Based on the results, a nozzle was customized to investigate the effects of print parameters, namely, printing speed (50–200 mm/s), printing height (5–40 mm), and extrusion velocity (96–288 mm/s), on printing quality. The reduction of printing speed increased the limits of layer thickness. Finally, the relationship among nozzle dimensions, print parameters, and filament dimensions was found, which can be used to pre-estimate the printing quality before printing and help preset appropriate printing parameters.