Valorization of Coal Mine Overburden as Sustainable Aggregate in Concrete Using Geotechnical and Geological Characterization

ABSTRACT Large‐scale coal mining in India produces vast overburden (OB) waste, contributing to land and environmental issues. This study is the first to evaluate OB from the Bhowra and Dhansar mines (Jharia Coalfield) as a sustainable alternative to conventional coarse aggregates in concrete. Five tons of OB were collected, processed, and subjected to comprehensive geotechnical, mineralogical, and mechanical characterization per Indian Standard methods. OB‐based mixes (25%–100% replacement) demonstrated specific gravity (2.77–2.52), water absorption (1.02%–2.21%), and bulk density (1.61–1.38 kg/L), with aggregate crushing and impact values meeting IS:383‐1970 guidelines. M‐30 concrete with Bhowra OB retained a compressive strength of 48 MPa at 56 days for 100% replacement, suitable for construction use. Mineralogical analysis identified primarily quartz, kaolinite, gypsum, hematite, and calcite, with high SiO 2 content and low hazardous metals. Microscopy and spectroscopic analyses confirmed mineral stability and absence of deleterious phases. The results show Bhowra OB is particularly effective at ≤ 50% replacement, providing strong mechanical performance and minimal strength loss. The findings present OB as a viable, environmentally responsible aggregate, potentially reducing the use of natural aggregates by 30%–50%, cutting mining waste by 5–10 Mt/year, and supporting circular economy goals in the construction industry.