Activated coal gangue refers to the processed form of coal mining waste, which is treated to enhance its pozzolanic properties, making it a beneficial supplementary cementitious material (SCM) for cement and concrete. The activation process involves mechanical grinding, thermal treatment, or chemical activation, transforming coal gangue into a reactive material that can replace a portion of Portland cement in concrete. This substitution not only reduces the carbon footprint associated with cement production but also addresses the environmental issue of coal gangue disposal.