Assessing the viability of using BOF steel slag treated with tartaric acid as coarse aggregate in concrete

Abstract

This study investigated the effectiveness of tartaric acid treatment in inhibiting the expansive behaviour of basic oxygen furnace (BOF) steel slag, aiming to optimize its utilization as a sustainable replacement for natural coarse aggregate in concrete. Tartaric acid-treated steel slag (TTSS) and non-tartaric acid-treated steel slag (NTSS) were comprehensively characterized for particle size and shape properties, physical and mechanical behaviour, and durability aspects including MgO stability factor and iron unsoundness. Chemical, morphological, mineralogical, and microstructural analyses were conducted using XRF, SEM-EDS, XRD, FT-IR, and optical microscopy, elucidating the impact of tartaric acid treatment. Compressive strength tests were then performed with TTSS incorporation levels of 30 %, 40 %, 50 %, and 0 % as reference batch (RB). As a result, TTSS showed 7.44 % and 10.92 % better physical and mechanical properties than NTSS respectively. Whereas on durability aspects, TTSS depicts 40 % better results on iron unsoundness and 36.43 % higher water absorption over NTSS. Furthermore, a maximum compressive strength of 44 MPa was achieved with a significant improvement of 15.80 % from RB. Additionally, TTSS aggregate-based cement concrete exhibited a denser microstructure and improved performance. This work highlights the potential of BOF steel slag as an aggregate resource, contributing to a circular economy and mitigating the environmental burdens associated with traditional aggregate production.