3D PRINTED CONCRETE BEAMS WITH VARIED REINFORCING TECHNIQUES' STRUCTURAL BEHAVIOUR

Abstract

3D printing of concrete (DCP) opens up a wide range of new options. By creating more efficient buildings, this technology has the potential to boost construction productivity while also reducing the industry's environmental effect.There has been very little work made into devising reinforcing techniques that are compatible with 3DCP and characterising their structural behaviour, despite major advancements in materials science. As a result, 3DCD does not meet structural integrity standards. Extrusion 3DCP beams reinforced with different forms of reinforcement were tested in nine four-point bending tests in this research. Steel cables (0.1 percent) or aligned end-hook fibres (0.3 and 0.6 percent) were employed as interlayer shear reinforcement. Unbonded post-tensioning and conventional bonded passive reinforcement were considered as options for longitudinal reinforcement. Digital image correlation was used to monitor the fracture patterns and their associated kinematics. As a consequence of concrete crushing during bending, the post-tensioned beams failed in a brittle manner, with deformations confined to a few bending fractures. The brittle failure of the interlayer shear reinforcement in the conventionally bonded longitudinal reinforcement reduced the ultimate load in the beams. As observed crack motions reveal, the interlayer shear reinforcement handled the bulk of the applied stress during the cracking process. Based on these findings, a simple mechanical model is developed to understand the mechanical behaviour and to pre-design the required amount of interlayer shear reinforcement.