Recycled wastes as vertical drain aggregates: a critical review and feasibility assessment

Vertical drains such as pre-fabricated vertical drains, sand drains, gravel drains, and earthquake drains are extensively used for accelerating pore water pressure dissipation in geotechnical engineering. However, the reliance on synthetic and natural aggregates raises economic and environmental concerns due to high carbon footprints and rapid resource depletion. Simultaneously, solid waste management remains a critical global challenge. This review investigates the potential of utilising waste-derived materials – namely, recycled construction and demolition wastes, tyre-derived aggregates, and bottom ash from waste-to-energy plants – as sustainable alternatives to traditional drain materials. Their geotechnical properties, environmental implications, and applicability in vertical drainage systems are critically examined. The findings suggest that waste-derived materials can serve as a viable and eco-friendly substitute in vertical drainage applications, promoting both resource conservation and waste minimisation.