Optimization of Mix Proportion and Performance Study of 3D-Printed Concrete for Slope Protection (2026-04)¶

To promote the automated construction of slope protection engineering, this study proposes a stepwise optimization strategy of “solid waste substitution + fiber reinforcement” and conducts mix proportion optimization research to address the problems of shrinkage cracking and weak interlayer bonding in the application of 3D-printed concrete (3DPC). The crack resistance and interlayer bonding performance of 3DPC are initially improved by incorporating fly ash (FA) and silica fume (SF), and then further enhanced by adding polypropylene (PP) fibers. The workability, mechanical properties and early-age crack resistance of the concrete are systematically evaluated. The results show that the optimal mix proportion is 20% FA + 10% SF + 0.4% PP fibers. Compared with ordinary 3D-printed concrete, the early-age cracking of the optimized concrete is completely suppressed, and the compressive strength, flexural strength and interlayer splitting tensile strength are increased by 29.5, 17.7 and 56.7%, respectively. Microscopic analysis reveals the synergistic enhancement mechanism of solid waste materials. This study provides a practical material solution for the automated construction of medium-sized high and steep slope protection.