Utilizing CO2 mineralization and aluminate synergistic activation of metallurgical solid waste to produce highly reactive powders: Toward sustainable engineering materials

Carbonation treatment can improve the hydration reactivity of steel slag powders. However, the reaction rate and degree of CaCO 3 contained in carbonated steel slag powders were usually low, which cannot fully exert its hydration reactivity. This paper utilized a synergistic strategy of CO 2 mineralization and aluminate activation to fully stimulate the hydration reactivity of ladle furnace slag (LFS), and prepared highly reactive powders (HRPs). There was a significant synergistic hydration effect between carbonated LFS and MK. CaCO 3 in carbonated LFS and the active aluminum phase in MK could generate monocarbonate in the early - age hydration, while consuming Ca(OH) 2 , which greatly refined the pores of cement-based materials and improved the interface structure between steel slag particles and matrix. At the age of 3 day, the compressive strength of cement mortar mixed with carbonated LFS was 2.1 MPa higher than that mixed with LFS. The addition of MK could increase this effect to 7.7 MPa. When the dosage reached 40 wt%, the compressive strength of composite cement at 3 day, 7 day, and 28 day was much higher than that of pure cement mortar. This article provides theoretical and technical support for exploring the characteristics and reaction mechanisms of Ca - containing alkaline solid waste and aluminum - rich solid waste, optimizing carbonation processes and composite schemes, and achieving sustainable development and carbon neutrality. • Highly reactive sustainable engineering materials were prepared using metallurgical solid waste. • The effect of CO 2 mineralization on the composition and microstructure of ladle furnace slag powder was investigated. • The synergistic hydration mechanism between carbonated ladle furnace slag powder and metakaolin was revealed. • The influence mechanism of highly reactive powders on the microstructure of cement-based materials was revealed.