Experimental study on in-situ mesh fabrication for reinforcing 3D-printed concrete

The lack of reinforcements persisted as a significant issue in 3D-printed concrete, particularly concerning the continuous vertical reinforcement along the direction of mortar stacking. This paper introduced an in-situ mesh fabrication technique that involved injecting high-flowability material to connect reinforcement segments, resulting in a reinforcing mesh within the stacked mortar. Parallel and interwoven reinforcing steel fibers were inserted and epoxy-coated in-situ within the cast and 3D-printed beams for flexural experiments and interfacial characterizations. The in-situ fabricated mesh exhibited more significant enhancement than the parallel independent reinforcements, both in the horizontal and vertical directions, achieving a maximum flexural enhancement of 123.6 % by an epoxy-coated steel fiber mesh. The high-flowability epoxy healed the gaps inside the concrete caused by the mesh fabrication. This paper provides experimental validation for the feasibility of reinforcement integration in all directions within the final 3D-printed concrete structure, thereby supporting the practical application of 3D printing technology.