Advances in Sustainable Geotechnical Engineering: A Review of Bio-mediated Soil Stabilisation, Cellular Confinement Systems, and Waste-Based Soil Improvements

The growing demand for sustainable infrastructure has accelerated the evolution of environmentally responsible practices in geotechnical engineering. Traditional soil improvement techniques, particularly those dependent on cement and lime, are associated with high carbon emissions, significant energy consumption, and long-term ecological consequences. In response, a new generation of green technologies has emerged, aiming to enhance soil performance while minimising environmental costs. This review explores three innovative approaches to sustainable ground improvement: bio-mediated soil stabilisation with a focus on Microbially Induced Calcite Precipitation (MICP), Cellular Confinement Systems (CCS), and waste-based soil improvement techniques. Bio-mediated methods offer biologically driven alternatives to chemical binders by promoting calcite precipitation, which strengthens soil and reduces erosion with a relatively low carbon footprint. CCS systems increase mechanical stability by redistributing loads through a geocellular matrix, often composed of recyclable or biodegradable materials. Waste-based improvements leverage industrial, agricultural, and construction-derived by-products such as fly ash, rice husk ash, and recycled concrete aggregates to enhance soil properties while advancing circular economy goals and reducing dependence on virgin resources. A comparative assessment highlights that each technique exhibits distinct advantages and limitations in terms of performance, environmental impact, scalability, and field applicability. Key challenges include regulatory uncertainty, material variability, and questions about long-term durability. Future directions point toward hybrid approaches that integrate multiple methods, AI-enabled monitoring systems to optimise treatment outcomes, and supportive policies that encourage widespread implementation. Taken together, these advancements mark a significant transition toward more resilient, efficient, and sustainable geotechnical engineering practices.