Experimental studies on coal mine over-burden incorporated concrete as a sustainable substitute for fine aggregate in concrete construction

Abstract The growing demand for sustainable construction has encouraged the exploration of utilizing industrial waste in cementitious materials, aiming to conserve natural resources and manage industrial waste efficiently. This study focuses on incorporating coal mine overburden (CMOB) as a substitute for natural fine aggregate in concrete mixes. The research systematically assesses concrete properties at curing ages of 28, 56, and 90 days. Laboratory tests are conducted to examine compressive strength, splitting tensile strength, flexural strength, and impact resistance of CMOB-incorporated concrete. Incorporating CMOB up to a 60 % replacement level enhances concrete strength, impact resistance, resistance to water penetrability, and microstructure. Optimal mechanical strength, enhanced impact resistance, and improved transport properties are achieved at this level, resulting in a 10–35 % increase in strength and a 13–29 % improvement in resistance to water penetrability compared to control concrete. Microstructural analysis indicates similarities in surface morphology and micro-cracks within the interfacial transition zone (ITZ) to normal concrete. Given the high water absorption of CMOB, the use of superplasticizers is advisable to maintain the desired workability. These findings support the practical utilization of CMOB in concrete applications, offering potential environmental and economic benefits.