Design and multi-scale characterisation of low-carbon soil stabiliser through simplex centroid optimisation of the steel slag-phosphogypsum-slag ternary system

The aim of this study was to develop a low carbon supersulfate cement (SSC) soil stabiliser agent based on Steel Slag (SS)-Phosphogypsum (PG)-Ground Granulated Blastfurnace Slag (GGBS). The mechanical and durability properties were evaluated by optimising the proportions using the simplex-centroid method. The results showed that the compressive strength of SS-PG-GGBS (SPG)-SSC peaked at a water-cement ratio of approximately 0.25. The optimum proportion of 13.3% SS, 23.3% PG, and 63.3% GGBS resulted in a compressive strength of 84 MPa and a flexural strength of 9.1 MPa. The increase in SS content resulted in a significant increase in drying shrinkage. The strength of the SPG-SSC stabilised river silt stabilised was superior to that of the Portland cement with the same dosage. Microcharacterisation revealed that Ettringite formation and dense structure were the key mechanisms for strength development. This study provides a basis for the application of SSC to roadbed stabilisation.