Sustainable integration of coal mine overburden as a substitute for natural sand in concrete to enhance its mechanical and durability properties

The viability of coal mine overburden (CMOB) as a sustainable substitute for natural sand (NS) in concrete production is investigated in this study, with a specific focus on the critical aspects of strength and durability. The reliability of select nondestructive testing (NDT) methods for evaluating the mechanical and durability properties of CMOB-incorporated concrete is rigorously validated. It is revealed that concrete strength and durability are significantly enhanced by the replacement of NS with CMOB up to 60%. Optimal mechanical strength, minimal void content, improved transport properties, and excellent chloride resistance are attained at this replacement ratio. Replacing 60% of NS with CMOB results in a substantial enhancement, with strength properties increasing by 10-35% and durability properties by 10-75%, compared to the control concrete made solely with NS. Furthermore, analytical models for estimating durability properties based on measurable strength characteristics are introduced, offering a practical quality assurance tool for construction projects. This research marks a significant step towards sustainable construction practices by validating NDT methods for evaluation of CMOB-incorporated concrete.