A new scattering-filling process for regulating coarse aggregate and fiber spatial distribution in ultra-high performance concrete

In this study, a novel scattering-filling coarse aggregate process (SFCAP) was employed to prepare sustainable coarse aggregate ultra-high performance concrete (CA-UHPC) without compromising performance. The spatial distribution of CAs and steel fibers in the CA-UHPC were identified by artificial intelligence recognition technology to reveal the mechanism of SFCAP method on improving performance with high CAs contents compared to ordinary preparation process method. The experimental results showed that the SFCAP method could enhance the mechanical properties of CA-UHPC by 10% even at higher CAs content of 40%. Moreover, the SFCAP method improved the CAs homogeneity by 90% and optimized their orientation. The distance among CAs was shortened by SFCAP method, which was conducive to format a tight interlocking skeleton structure inside CA-UHPC. Additionally, the SFCAP method optimized the coordination between steel fibers and CAs and increased cracking paths, resulting in enhanced mechanical properties. Microstructure analysis indicated that the SFCAP method could improve the interface transition zone between CAs and paste and reduced the porosity of CA-UHPC. regression analysis was conducted to connect the spatial parameters of CAs and steel fibers with the mechanical properties of CA-UHPC, further emphasizing the feasibility of the SFCAP method in the production of CA-UHPC. Finally, the sustainability of CA-UHPC prepared by SFCAP method was demonstrated by energy consumption intensity, CO₂ emission intensity and cost intensity analyses.