High-performance concrete (HPC) represents a class of concrete with enhanced mechanical and durability properties, achieved through careful selection of materials and mixture proportions. The use of activated coal gangue as a supplementary cementitious material (SCM) in HPC is an innovative approach to improve concrete performance while addressing environmental concerns associated with coal gangue disposal. Activated coal gangue, processed through mechanical grinding, thermal treatment, or chemical activation, possesses pozzolanic properties that enhance the concrete matrix’s strength and durability.