Pumping-less 3D concrete printing using quick nozzle mixing

Abstract

Nozzle technologies for 3D concrete printing have been evolving to balance the conflicting demands of buildability and pumpability. This study introduces a simplified approach that eliminates the need for pumping by developing a customized system, the parameters of which were evaluated. The effect of process parameters (i.e., the flow rates of liquid and solid materials) and mixture proportions (i.e., the ratios of powder to sand and liquid to solid) on the extrudability and print quality was explored. Furthermore, the mechanical properties and microstructure of concrete printed using the Quick Nozzle Mixing system were examined. Results show that Quick Nozzle Mixing Technology not only enables high-quality printing but also exhibits the potential for achieving better process efficiency and higher aggregate content. The water-to-solid ratio is a critical factor influencing extrudability and buildability. Due to anisotropy caused by this new method, printed concrete has a lower strength than cast concrete.