Study on the mechanical properties of 3D printing concrete layers and the mechanism of influence of printing parameters

This paper introduces the influence of printing parameters (printing layer height, velocity, and time gap) on the bond strength (splitting tensile strength and shear strength) between 3D printing concrete layers. The optimal parameters were obtained through orthogonal and single-factor experiments. The layer height is 8 mm, the time gap is 10-15 min, and the velocity is 1.6 m/min. The influence mechanism of the parameters was discussed. The ratio of the layer height and the nozzle diameter is defined as the layer-diameter ratio D. with the increase of D, the printing materials change from overlapping to wavy swing. The increase of printing velocity reduces the height and width of printing concrete. The influence of the time gap on the bond strength of concrete shows a trend of first decreasing and then increasing. Due to the existence of maternal bleeding, the surface water content increases within 10-15 min, and the splitting strength and shear strength increase accordingly.