Review on solid wastes incorporated cementitious material using 3D concrete printing technology

The substitution of cement, natural sand, and synthetic fibers in concrete with solid wastes substantially reduces CO₂ emissions. Incorporating solid wastes into 3D printed concrete, which reduces CO₂ emissions from labor and formwork, can achieve innovative low-carbon construction materials. However, the previous studies lack a comprehensive review on the inherent characteristics of various solid wastes and their impacts on the printability, mechanical performance, and functionality of 3D printed concrete. This paper reviews the present state of research and introduces feasible methods for the sustainable use of solid wastes in 3D printed concrete. Numerous types of solid wastes are investigated comprising their benefits, shortages, and fit dose to guide in selecting the optimal solid waste to enhance the performance of printed concrete. Additionally, the printability, functionality, and mechanical strength of printed concrete with solid waste addition are quantified and summarized. The preliminary exploration to achieve a balance between multi-functionality and mechanical properties using mixed solid wastes is conducted for 3D concrete printing. Finally, machine learning, broadening raw material sources, automated monitoring systems, multi-functionalized composite, and BIM are proposed to address current challenges.