Ontology Framework for Sustainability Evaluation of Cement–Steel-Slag-Stabilized Soft Soil Based on Life Cycle Assessment Approach

Steel slag has become a promising supplementary cementitious material for soft soil stabilization. However, there is a lack of research on the integrated assessment of cement–steel-slag-stabilized soft soils (SCSs) from the performance, environmental, and economic perspectives. In this study, an ontology framework for the sustainable evaluation of SCSs was developed based on the life cycle assessment (LCA) approach, which combined a knowledge base with semantic web rules to achieve an automated decision design for soft soil stabilization, considering comprehensive benefits. The ontology framework was applied to a marine soft soil stabilization case to verify its scientificity and practicability and to evaluate the influence of the fineness, carbonation degree, and substitution ratio of steel slag on the sustainability of SCSs. The results show that, when compared to pure-cement-stabilized soil (S-C), using 10% and 20% of fine steel slag carbonated for 18 h (FSS-C-18h) as cement substitutes can significantly reduce carbon emissions and costs while achieving a similar strength performance as S-C, demonstrating the feasibility of steel slag as a sustainable supplementary cementitious material for soft soil stabilization.