Experimental and Numerical Study on the Flexural Behavior of 3D Printed Composite Beams with U-Shaped ECC Formwork (2024-05)¶

The conventional challenges of 3D-printed concrete reinforcement have yet to be resolved, and employing Engineered Cementitious Composites (ECC) as a 3D-printed prefabricated formwork seems to be a viable solution. This study conducted experiments on the flexural behavior of composite beams with variations in fabrication processes, fine aggregate replacement ratio, single-layer printing height of side panel, and bottom ECC printing height. Additionally, the finite element analysis which considered the thickness of the side panels and the strength of post-cast core concrete was also performed. The findings indicated that composite beams formed by 3D-printed ECC exhibited superior flexural capacity and peak displacement in bending compared to beams constructed using cast formwork. The 3D-printed composite beams with a ratio of the bottom ECC height to the beam height of 0.2 and the side panel thickness of 30 mm, demonstrated bearing capacities similar to reinforced concrete beams with reinforcement ratios ranging from 0.3% to 0.4%, and exhibited larger peak displacements. Furthermore, the improvement of bearing capacities in composite beams through increased side panel thickness and core concrete strength was limited by the bonding strength at the interface between the ECC formwork and core concrete.