Effects of Key 3D concrete printing process parameters on layer shape: Experimental study and Smooth Particle Hydrodynamics modelling

3D concrete printing (3DCP) is an innovative technology with significant potential in construction. However, it faces critical challenges in achieving precise layer geometry and dimensional accuracy, as small geometric deviations in individual layers can compromise the stability and performance of the entire structure. To investigate the underlying deformation mechanisms, this study develops an integrated analysis framework combining experimental study with Smooth Particle Hydrodynamics (SPH) modelling. Key rheological and process parameters for 3DCP are identified experimentally. For the first time, a novel three-dimensional (3-D) SPH model is devised to simulate single- and double-layer concrete printing processes, considering nozzle moving speed, material inlet speed, and nozzle height. The high consistency between experimental and SPH results demonstrates the accuracy of models in predicting layer shape and tracking inter-layer deformations. Parametric analysis reveals a self-compensatory effect of nozzle height on layer height variations and demonstrates that a lower nozzle speed to material inlet velocity ratio improves layer shape and structural performance. These findings provide insights into the control of construction materials to enhance printing quality and structural reliability in 3DCP.