Microstructural characterization of 3D printed concrete

Abstract 3D concrete printing technique offers a novel approach to build new infrastructure. However, the microstructure of 3D printed concrete has rarely been studied so far. This study presents the microstructural characterization of 3D printed concrete by using MIP and X-ray CT. The void size distribution reported in this study covers a wide spectrum. The mechanical performance of the 3D printed concrete, along different directions, is also investigated. This study reveals that a higher amount of macropores and large voids are present in the 3D printed samples, attributed to the movement of the printhead , elimination of vibration, and rapid moisture loss. Moreover, the morphologies of the voids are more irregular and elongated. This is more pronounced at the interlayer than in the filament. As a result, the strength of 3D printed samples is lower than that of mould-cast specimens.