Magneto-assisted 3D printing of steel fiber-reinforced concrete for enhanced buildability and interlayer bonding

This study developed a proof-of-concept system to enhance the buildability and interlayer bonding of 3D printed steel fiber-reinforced concrete by applying magnetic stimuli after filament deposition. The results indicate that the cumulative height of the bottom layers directly above the magnetic field increased by 6.9% compared to unmagnetized regions, due to the increased stiffness of cementitious materials and vertical expansion of magnetically induced fiber alignment. However, this was accompanied by increased surface irregularities, characterized by fibers protruding from the filament surfaces. The magnetic intervention had a negligible effect on the acoustic and compressive properties in the transverse (Y) and height (Z) directions, but caused slight reductions of 2.1% and 7.9% in the printing (X) direction, respectively. In addition, the interlayer bonding strength increased by 31.1%, mainly attributed to the bridging effect of magneto-aligned fibers crossing the interfaces, as evidenced by the fiber distribution and orientation findings obtained from X-ray computed tomography. This study provides experimental support for the enhancement of buildability and interlayer bonding in 3D printed members by magnetic methods, validating the feasibility of applying magnetic intervention in assisting 3D concrete printing. © 2026 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.