Performance of Pre-Carbonated Basic Oxygen Furnace Slag as a Replacement for Natural Coarse Aggregates in Concrete
Tsematse TSEMATSE, Lewis PARSONS, Sunday NWAUBANI
Abstract. Basic Oxygen Furnace Slag (BOFS) is a significant by-product of the steel-making process, where over 250 million tonnes is produced annually around the world. However, the utilisation rate of the steelmaking by-product remains low due to the expansive hydration products formed by the BOFS. To support the potential high-volume use of the by-product as coarse aggregate in concrete, this study aimed to investigate the use of pre-carbonation over 7 days to pre-react the constituents that cause expansive behaviour. For this purpose, five concrete mixes were designed with a volumetric replacement of the Natural Coarse Aggregates (NCA) with the BOFS and the pre-carbonated BOFS (BOFC) at 0, 50 and 100% replacement percentages. X-ray diffraction (XRD) and water absorption analyses were conducted on both types of BOFS aggregates to support the compressive strength, prism expansion, and oxygen permeability tests, which were also performed in the study. The results from the compressive strength test showed a 10.7% and 1.4% higher 56–day compressive strength result for the concrete made with BOFC and BOFS, respectively, compared to the natural aggregates. Similarly, the oxygen permeability test showed that the concrete made with 50% BOFC was 2% less permeable than the untreated BOFS and at 28-days of curing, exactly the same compared to NCA mixes.. Lastly, the prism expansion test indicated that pre-carbonating the BOFS improved the volumetric stability of concrete made with BOFS over the 84-day curing regime. Therefore, the above results suggest that pre-carbonation can increase the utilisation rate of BOFS as a coarse aggregate in concrete.
Keywords
Carbon Dioxide, Durability, Concrete, Aggregate, Basic Oxygen Furnace Slag
Published online 4/2/2026, 11 pages
Copyright © 2026 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Tsematse TSEMATSE, Lewis PARSONS, Sunday NWAUBANI, Performance of Pre-Carbonated Basic Oxygen Furnace Slag as a Replacement for Natural Coarse Aggregates in Concrete, Materials Research Proceedings, Vol. 63, pp 175-185, 2026
DOI: https://doi.org/10.21741/9781644904053-20
The article was published as article 20 of the book Advances in Cement and Concrete Research
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
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