Eco-bricks reinvented: transforming coal mine overburden and fly ash into sustainable building solutions

The escalating demand for construction materials coupled with the challenges of waste management has necessitated the development of sustainable alternatives. This study explores the potential of utilizing industrial by-products, namely coal mine overburden (OB) and fly ash (FA), for fabricating solid bricks compliant with IS: 12894 standards. Bricks were prepared with varying compositions of OB and FA, while keeping cement and sludge lime proportions constant. Physio-chemical analyses of the raw materials and manufactured bricks were conducted. The bricks were evaluated for compressive strength, water absorption, efflorescence, bulk density, and traces of heavy metals. The optimal composition—60 wt% fly ash, 20 wt% OB, 7 wt% cement, and 13 wt% sludge lime—achieved a compressive strength of 7.87 MPa. The study underscores the potential of these bricks for non-load bearing applications and highlights their contribution to sustainable waste management and economic circularity.