Mechanical and macrostructural properties of 3D printed concrete dosed with steel fibers under different loading direction.

• 3D printed concrete is prepared with steel fiber and showed nice buildability and printability. • 3D printed concrete performs well when printing layers are 90° to the loading orientation. • Fractal dimension does not present a statistical self-similarity in 3D printed concrete. Currently, the 3D manufacturing of cementitious materials is at the preliminary stage. The utilization of the various materials and the anisotropic behavior of 3D printed mix is still an uncharted section. This study investigates the significance of loading orientation on 3D printed concrete infilled with steel fibers. The fresh characteristics and compressive strength were tested using conventional techniques under different loading directions (0°, 45° and 90°). Whereas porosity, fractal characteristics and failure planes of the 3D printed concrete were characterized using X-Ray computed tomography (X-CT). The fractal characteristics and porosity showed a strong correlation between each other. Moreover, the tradeoffs between the layer orientation and loading planes directly reduce the compressive strength. The mix with 0.75% of steel fibers showed the highest compressive strength at an angle of 90° to the loading direction. No interlayer pores were observed in the X-CT scan because of the better quality and compaction of the 3D printed concrete. [ABSTRACT FROM AUTHOR]