Mechanical Properties and Failure Mechanism of 3D Printing Ultra-High-Performance Concrete (2024-08)¶

Steel fiber reinforced 3D printing ultra-high performance concrete (3DP-UHPC) is prepared and experimentally studied. The effects of steel fiber content and various interlayer reinforcing materials on compressive, flexural, and splitting tensile properties are investigated, supplemented by Digital Image Correlation (DIC) technique for crack propagation analysis. Fabricated 3DP-UHPC specimens exhibited compressive strengths exceeding 160 MPa, with a peak at 205.2 MPa. Incremental increases in steel fiber content slightly enhanced compressive strength, whereas the addition of interlayer reinforcing materials, textile/steel wire mesh (SWM), reduced it due to altered interlayer bonding characteristics. The incorporation of textile/SWM significantly improved the flexural performance, enhancing energy absorption capacity and toughness. Specimens reinforced with SWM exhibited excellent flexural performance, with their flexural strength and ultimate deflection reaching 110.9 % and 192.5 % respectively of those before reinforcement. The splitting test revealed typical fractures along the interfaces between printed layers, with higher splitting strength obtained in the bottom layers. In specimens reinforced with carbon textile, glass textile, and SWM, the splitting strengths were more than double those of the subsequent layers. These insights contribute to a deeper understanding of 3DP-UHPC, paving the way for optimized use of reinforcing materials to improve structural integrity and performance.