Influence of fine particle content on soil stabilization using KR desulfuration slag

This study investigates the potential of Kambara Reactor (KR) desulfurisation slag, a by-product of the steel industry, as a soil stabiliser. KR slag, with low swelling potential, is mixed with three different soils (Sa100, Sb100, and Sc100) at an 80:20 soil-to-KR ratio. The influence of fine particle content on stabilisation effectiveness is evaluated using standard geotechnical tests like the California Bearing Ratio (CBR) and expansion tests. Analytical techniques such as X-ray fluorescence spectrometry, scanning electron microscopy (SEM), and X-ray diffractometry are used to explore the stabilisation mechanisms. Results show that soils with higher fine contents and longer curing periods achieve better CBR values, indicating the role of clay minerals and curing time in stabilisation. Chemical analysis suggests that the cation exchange between soil minerals and the calcium oxides in KR slag plays a key role in the stabilisation process. SEM images show needle-like structures in soils with higher clay content, potentially contributing to improved mechanical performance. The proposed soil–KR interaction model suggests that the dissolution of KR slag releases Ca²⁺, Mg²⁺, and OH⁻ ions, which interact with soil minerals to enhance densification and stabilisation, particularly in clay-rich soils.