Hydration of potassium citrate-activated BOF slag

Basic Oxygen Furnace (BOF) slag is currently utilized with low-grade applications or landfilled. Here, we investigate a novel route to upgrade BOF slag to a high-performance binder by chemical activation with tri-potassium citrate. The impact of tri-potassium citrate on hydration and phase assemblag...

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Bibliographic Details
Published in:Cement and concrete research 2021-02, Vol.140, p.106291, Article 106291
Main Authors: Kaja, A.M., Schollbach, K., Melzer, S., van der Laan, S.R., Brouwers, H.J.H., Yu, Qingliang
Format: Article
Language:English
Subjects:
Basic converters
BOF slag
Brownmillerite
Calcium aluminum ferrite
Calcium silicate hydrate
Chemical activation
Compressive strength
Dicalcium silicate
Heavy metals
Hydration
Kidney stones
Leaching
Microstructure
Oxygen steel making
Pastes
Potassium
Reaction kinetics
Slag
Soil porosity
Tri‑potassium citrate
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Summary:Basic Oxygen Furnace (BOF) slag is currently utilized with low-grade applications or landfilled. Here, we investigate a novel route to upgrade BOF slag to a high-performance binder by chemical activation with tri-potassium citrate. The impact of tri-potassium citrate on hydration and phase assemblage of BOF slag is analyzed with a multi-technique approach. Results reveal that the addition of tri-potassium citrate considerably enhances the reactivity of brownmillerite and accelerates the hydration of belite at early ages. The majority of brownmillerite hydrates within 24 h, and the reaction kinetics is controlled by the activator dosage. The main products of BOF slag hydration are siliceous hydrogarnet and C-S-H gel. Acting as a strong water reducer, tri-potassium citrate enables the manufacture of slag pastes with high compressive strength (up to 75 MPa at 28 days) and low porosity. Leaching of heavy metals from the slag pastes fulfills the Dutch Soil Quality Decree limits.
ISSN:0008-8846
1873-3948
DOI:10.1016/j.cemconres.2020.106291