Experimental Study on Crack Development and Fracture Performance of 3D Printed Green Engineered Cementitious Composites (2025-10)¶

The 3D printing technology is increasingly being recognized as a promising method for concrete fabrication in the construction industry due to its advantages of high efficiency, personalization, and the elimination of formwork. However, Engineered Cementitious Composites (ECC), a crucial material for 3D printing processes, have faced limitations in large-scale application due to their high cost and environmental impact. To enhance the green sustainability of 3D printed ECC, this study substitutes recycled concrete powder (RCP) and recycled brick powder (RBP) for quartz sand at a 1:1 ratio, partially replaces cement with recycled glass powder (RGP), (with particle sizes 75-150 μm), and polyethylene (PE) fibers are partially replaced by recycled polyethylene terephthalate (PET). Using RGP and PET substitution rates as variables, cast specimens were used as a control group, the crack development, crack mouth opening displacement (CMOD), fracture toughness and fracture energy of 3D printed green ECC were discussed by a three-point bending experiment on a single-edge notch beam. The results indicate that the 3D printed specimens exhibit significantly faster crack initiation and propagation compared to the cast specimens. PET fibers are less effective in bridging ability than PE fibers, and their incorporation has an overall negative effect on instability fracture toughness. However, the incorporation of RGP in the 3D printing process mitigates the negative impact, especially at PET substitution rates of 30 % and 40 %, fracture toughness significantly increases at high RGP substitution rates (25 %). The synergistic effect of RGP and PET fibers significantly improve the fracture properties of 3D printed green ECC.