14 - Latest development of 3D printing adopting recycled aggregate

Abstract

3D concrete printing has received worldwide attention while the development on recycled aggregates for 3D printing is inadequate. In this study, a printing system including supporting subsystem, controlling subsystem, feeding subsystem, and extruding subsystem was developed by considering the properties of the 3D mortar printing (3RMP) with recycled sand, and which employed the recycled sand instead of natural sand to achieve 3D concrete printing and investigated the mechanical behavior and hardened properties of this extrusion-based material. The effects of replacement ratio of recycled sand, curing age, nozzle height, and anisotropic behavior were evaluated based on the compressive tests, tensile splitting tests, and flexural tests. Moreover, the digital image correlation (DIC) technique was adopted to capture the strain behavior and failure pattern of this layered and printed concrete. The compressive, tensile splitting, and flexural strength of 3D printed concrete with recycled sand had obvious anisotropy. The replacement of recycled sand had limited effect on the anisotropy of compressive and flexural strength, but had certain effect on the tensile splitting strength. Since recycled sand is one of those major products derived from the construction and demolition waste, it is believed that the employment of recycled sand to the mix of 3D printed concrete will significantly improve the sustainability of 3D printed concrete structures.