Abstract
This study evaluated the innovative use of basalt rock powder (BRP), a by-product of basalt mining, as an eco-friendly stabilizer for soft clay soils, with a particular focus on Kasaoka clay in Japan. The challenges associated with managing clay-rich surplus soils—such as poor engineering properties, high water retention, and disposal restrictions—were addressed by utilizing BRP in combination with blast furnace cement type B (BFCB) to form a hybrid stabilizer. Laboratory experiments were conducted to assess the geotechnical performance, environmental benefits, and scalability of the proposed stabilization approach. The results showed that BRP significantly improved the strength and compaction characteristics of Kasaoka clay. At a BRP content of 30%, the treated clay met embankment material standards, achieving a cone index ( q c ) greater than 800 kN/m 2 . Furthermore, the hybrid stabilizer combining BRP and BFCB demonstrated enhanced strength gains due to synergistic reactions. The maximum dry density ( ρ dmax ) increased from 1.51 g/cm 3 for untreated clay to 1.65 g/cm 3 for BRP-treated clay, with further optimization observed in the hybrid mixes Environmental analysis highlighted the potential for significant reductions in CO 2 emissions through the use of BRP. Compared with conventional stabilizers such as ordinary Portland cement, the hybrid stabilizer reduced CO 2 emissions by 59.3% without carbonation and by 78.1% when carbonation was considered. These findings underscore the sustainability benefits of the proposed method, aligning with global efforts to reduce the carbon footprint of construction materials. In conclusion, the study demonstrates that the BRP–BFCB hybrid stabilizer offers a promising solution for the sustainable reuse of industrial by-products in soil stabilization. It effectively addresses technical challenges while promoting resource efficiency and environmental sustainability. Future research is recommended to validate these results through field-scale studies and to explore the incorporation of additional waste materials to further enhance performance and cost-effectiveness.