Mining overburden sand from lignite mines as a partial replacement for fine aggregates in concrete

Abstract

Extensive opencast mining activities have resulted in massive generations of overburden dump materials which have become a significant global contributor to environmental pollution, land degradation and pose a threat to environmental sustainability. This study explores the potential of utilizing overburden material of the Neyveli lignite mine area as a sustainable alternative to natural river sand for construction application. The research involves a comprehensive physio-chemical and mechanical analysis of overburden sand extracted from the Neyveli mine site area, assessing its mineral contents, distribution of particle sizes and compressive strength. The result reveals that overburden sand is predominantly composed of quartz and alumina, meets IS standards for fine aggregates and demonstrates comparable performance to manufactured sand. Concrete specimens incorporating overburden sand exhibited satisfactory strength with a compressive strength of 58 MPa at 28 days, which is comparable to manufactured sand-based concrete 60 MPa at 28 days. Additionally, XRD, XRF, SEM and sieve analysis confirmed that overburden extracted sand possesses desirable properties for construction applications. The study highlights the dual benefits of repurposing overburden i.e., reducing environmental hazards and mitigating the depletion of natural sand resources in rivers. Overburden extracted sand proves to be a viable and eco-friendly substitute for fine aggregates. Further studies on long-term durability, large-scale implementation and economic feasibility are recommended to enhance its widespread adoption in sustainable construction.