Abstract: Three-point bending tests were conducted on coal gangue concrete with I-shaped fractures. The aim was to investigate the impacts of coal gangue mass replacement rate, fly ash mass replacement rate, and water-cement ratio on load-crack opening displacement curve, load-midspan deflection curve, fracture toughness, and fracture energy. The obtained results were utilized in association with damage mechanics and the Weibull distribution function to establish the fracture damage constitutive model of coal gangue concrete. The findings indicate that the coal gangue mass replacement rate exerts the most significant influence on the fracture performance of coal gangue concrete with prefabricated I-type cracks, while fly ash mass replacement rate has a greater impact on the fracture toughness, and the water-cement ratio exhibits a greater influence on fracture energy. The optimal combination for enhancing the fracture toughness and fracture energy of coal gangue concrete is determined as follows: 25% coal gangue mass replacement rate, 10% fly ash mass replacement rate, and 0.5 water cement ratio. Upon comparison, the stress-strain curve derived from the constitutive model aligns closely with the test curve. These findings offer valuable insights for the formulation and practical application of gangue concrete.

Key words: coal gangue concrete, orthogonal test, fracture toughness, fracture energy, Weibull distribution, damage constitutive model