Sustainable approaches for soil stabilization: geotechnical and life-cycle perspectives

Abstract

Sustainable soil stabilization has emerged as a promising strategy for improving weak soils while reducing the environmental impacts associated with conventional cement-based treatments. This study presents a quantitative comparative assessment of four sustainable stabilizers—fly ash (FA), rice husk ash (RHA), lime kiln dust (LKD), and biochar—for the stabilization of low-plasticity clay, integrating geotechnical performance indicators, life-cycle environmental evaluation, and multi-criteria decision analysis. Data synthesized from 27 peer-reviewed studies published between 2020 and 2025 were analyzed to evaluate unconfined compressive strength (UCS), permeability reduction, resistance to initial cyclic degradation, carbon emissions, and energy consumption. The results indicate that all four additives improve soil performance relative to untreated clay. Among the evaluated materials, LKD provided the highest mechanical performance, achieving the greatest strength enhancement and the lowest degradation under reported low-cycle loading conditions. Fly ash demonstrated balanced geotechnical and environmental performance, whereas biochar exhibited a carbon-negative life-cycle footprint due to its carbon sequestration potential. Multi-criteria evaluation using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) ranked LKD as the most favorable overall alternative under equal weighting of engineering and environmental criteria. Unlike previous narrative reviews, this study integrates geotechnical performance, environmental sustainability, transport distance sensitivity, and decision-support analysis into a single comparative framework. The findings highlight the importance of balancing mechanical performance and environmental objectives when selecting sustainable stabilizers for geotechnical infrastructure projects. Limitations associated with heterogeneous literature datasets and the scarcity of long-term field validation data are also discussed to support appropriate interpretation of the results.