A Novel Arch Infill for 3D Concrete Printed Beams (2026-01)¶

3D concrete printing (3DCP) offers significant potential for creating structurally efficient and lightweight structures. Yet, its application is often limited by concrete’s weak tensile strength and a lack of extensive studies in this aspect. To address these issues, this study compares the flexural performance of 3D printed concrete beams having optimized internal geometries against traditionally cast solid beams. Six beam types with identical external cross-sections were fabricated and tested: solid cast beams, truss infill beams, and arch infill beams, all with and without fibers. Center point bending tests were conducted to evaluate load-bearing capacity and failure characteristics, and the strength-to-weight ratios of the beams were compared. The results revealed that the fiber-reinforced arch infill beam demonstrated the most superior performance, achieving a 10.1 % greater load carrying capacity and a 124.2 % higher strength-to-weight ratio than the solid fiber reinforced cast beam. Subsequently, a finite element (FE) model was also developed and validated against experimental results. Overall, the findings show that by combining optimized internal geometries, such as arches, and fiber reinforcement, 3DCP can fabricate lightweight structural elements that are significantly stronger and more material efficient than cast beams.