Reactor-controlled Carbonation Of Basic Oxygen Furnace Steel Slag For CO2 Uptake And Reactivity Enhancement As A Potentially Carbon-negative Supplementary Cementitious Material
Abstract
Utilizing basic oxygen furnace (BOF) steel slag for CO2 sequestration is attracting attention due to environmental and economic concerns regarding the management of steelmaking by-products and decarbonization of cement. In this study, BOF slag was carbonated using circulated and pressurized reactors, and the carbonation efficiency, mineral transformation, microstructural refinement, and reactivity enhancement were systematically evaluated. The circulated reactor enables rapid carbonation, achieving a CO2 uptake of 12.89 g CO2/100 g BOF within 2 h, while the pressurized reactor attains a higher overall uptake of 19.27 g CO2/100 g BOF after 24 h, both at ambient temperature. Carbonation induces pronounced mineral reconfiguration, marked by calcite formation, development of amorphous Si-rich gels, and progressive decalcification, with the surface Ca/Si ratio decreasing from 3.37 to 1.30 and 0.75 in the circulated and pressurized reactors, respectively. These changes are accompanied by significant particle refinement, reflected by increases in specific surface area of 227.51% and 610.32%, as well as rapid alkalinity neutralization. When used as a supplementary cementitious material (SCM), carbonated BOF slag shows enhanced reactivity. Overall, a higher carbonation degree is associated with higher reactivity, and regardless of reactor type, comparable carbonation degrees yield comparable reactivity. The formulation containing 20% pressurized-carbonated BOF (for 24 h) achieves a 7-day cumulative heat release of 237.08 J/g (96.1% of control) and a 28-day compressive strength of 41.7 MPa (i.e., 93.8% of control).
Recommended Citation
Y. Huang et al., "Reactor-controlled Carbonation Of Basic Oxygen Furnace Steel Slag For CO2 Uptake And Reactivity Enhancement As A Potentially Carbon-negative Supplementary Cementitious Material," Cement and Concrete Composites, vol. 174, article no. 106754, Elsevier, Nov 2026.
The definitive version is available at https://doi.org/10.1016/j.cemconcomp.2026.106754
Department(s)
Civil, Architectural and Environmental Engineering
Keywords and Phrases
BOF slag; Carbonation efficiency; Circulated carbonation reactor; CO2uptake; Pressurized carbonation reactor; Reactivity
International Standard Serial Number (ISSN)
0958-9465
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2026 Elsevier, All rights reserved.
Publication Date
01 Nov 2026
Comments
U.S. Department of Energy, Grant DE-FE0032395