Abstract
High-Al steel slags, such as ladle metallurgy furnace (LMF) slag, substantially retard the early hydration of cement when incorporated into cement pastes, primarily due to the high mayenite content. In this study, carbonation of slag at elevated temperatures of 60°C and 80°C, combined with gypsum addition, was proposed to synergistically mitigate the retardation effect and enhance the early-age strength of cement pastes. The physical and chemical properties of slags carbonated at various temperatures were analyzed to elucidate their impact on cement performance as a supplementary cementitious material. The results indicate that higher temperatures enhance carbonation reactivity, accelerating the carbonation of mayenite and katoite. The main carbonation products are calcite, Al gels, and gibbsite, the latter of which is absent under ambient temperature carbonation. Reactivity tests demonstrate that Al gels and gibbsite formed at higher temperatures tend to delay aluminum release into the solution at early stages and, thus, mitigate its inhibitory effect on C3S hydration when blended with cement. The synergistic effect of carbonation at elevated temperatures and the addition of gypsum could markedly enhance compressive strength, particularly at 1d and 3d, increasing by 10.8 and 14.2 folds, respectively. The addition of gypsum serves a dual function: first, it further suppresses the dissolution of Al phases; and second, it facilitates ettringite formation, which uses Al-rich phases to densify the microstructure.
Recommended Citation
N. Zhang et al., "Carbonated High-Al Steel Slag as Supplementary Cementitious Material: Synergy of Carbonation at Elevated Temperature and Addition of Gypsum," Construction and Building Materials, vol. 493, article no. 143088, Elsevier, Sep 2025.
The definitive version is available at https://doi.org/10.1016/j.conbuildmat.2025.143088
Department(s)
Civil, Architectural and Environmental Engineering
Publication Status
Full Text Access
Keywords and Phrases
Carbonation; Early-age hydration; Gypsum; High-Al slag; Ladle metallurgy furnace (LMF) slag; Strength
International Standard Serial Number (ISSN)
0950-0618
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2025 Elsevier, All rights reserved.
Publication Date
26 Sep 2025
