A critical review on reducing the environmental impact of 3D printing concrete: Material preparation, construction process and structure level.

[Display omitted] • This paper presents a critical review on sustainable 3D printing concrete (3DPC). • The performance of 3DPC based on recycled aggregate and fibre is investigated. • Effect of fibre on mechanical and anisotropic properties of 3DPC is evaluated. • Structural behaviour, environmental impact and cost of 3D printed strucrure is given. This paper presents a critical review of reducing the life-cycle environmental impact of 3D printing concrete (3DPC) systems from the perspectives of material preparation, construction process and structure level. The material requirements of 3DPC are first introduced, then the utilization of low-carbon cementitious materials, recycled aggregates, admixture and fibres in 3DPC is explored, along with their effect on workability and mechanical property. The potential for improving the environmental benefits by applying better design and printing parameters are discussed in the subsequent part. Two main delivery systems and the effect of printing parameters (including printing speed, standoff distance) are presented. Finally, the behaviour of 3D printing components (beam, slab and column) is examined at the structural level. 3D printing technology has a high degree of freedom, thus better understanding of the component behaviour can save materials and improve strength. Finding a balance between component's performance and environmental impact is a crucial work in future. [ABSTRACT FROM AUTHOR]