Potassium citrate-activated pure BOF slag-based mortars utilizing carbonated and autoclaved BOF slag aggregates

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Abstract

This study proposes novel basic oxygen furnace (BOF) slag mortars formulated with tri-potassium citrate (TPC) activated BOF slag as binder and treated BOF slag (carbonated (CB) and autoclaved (AB)) as aggregates, aiming to maximize the utilization of BOF slag in the construction industry. Untreated BOF slag (UB) and natural sand (NS) were employed as reference aggregates. The effects of carbonation and autoclaving were investigated, focusing on the interfacial transition zone (ITZ) properties through SEM-BSE greyscale thresholding and constituent segmentation analysis. Results indicate that both treatments reduce the free CaO, promote CaCO3 formation, and modify the aggregate surface. The 28 d compressive strength of pure BOF slag-based mortars with UB, CB, and AB aggregates are 25.8, 29.4, and 34.8 MPa (average at varying TPC dosages), significantly higher than that with NS (19.6 MPa). Pure BOF slag-based mortars also show narrower ITZ thicknesses and the absence of bond cracks. Mortars with CB and AB aggregates exhibit fewer unreacted particles and more hydration products within the integral binder region compared to those with UB. Overall, pure BOF slag-based mortars present a more robust aggregate/binder interface that is further enhanced by the aggregate treatments. Leaching values of all mortars are well below the Dutch legal limits. The findings suggest promising application prospects for pure BOF slag-based mortars in substituting cement mortars and valorizing BOF slag.
Original languageEnglish
Article number105564
Number of pages16
JournalCement and Concrete Composites
Volume150
Early online date29 Apr 2024
DOIs
Publication statusE-pub ahead of print - 29 Apr 2024

Funding

This work was supported by the China Scholarship Council (fund No. 201906950015, No. 202006950032). We also want to express our sincere gratitude to Anneke Delsing for assisting with the ICP-AES tests. The support of the research laboratories of Tata Steel Netherlands is acknowledged for facilitating the analysis and providing the raw materials.

FundersFunder number
China Scholarship Council201906950015, 202006950032

    Keywords

    • Autoclaving
    • BOF slag
    • Carbonation
    • Interfacial transition zone (ITZ)
    • Leaching
    • Tri-potassium citrate

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