The influence of coal gangue coarse aggregate on the mechanical properties of concrete columns

Abstract

Using coal gangue as coarse aggregate is one of the solutions for the sustainable development of construction engineering. In this paper, the mechanical properties of coal gangue concrete (CGC) columns are investigated. The test results show that the failure modes of CGC columns under different replacement ratios are similar. In the loading process, the strain difference between CGC and reinforcement is small, indicating that there is sufficient bonding force between them. Coal gangue coarse aggregate can not effectively prevent the expansion of cracks, resulting in a decrease in the crack resistance of CGC columns. With the increase of coal gangue replacement ratio, the total deformation of the specimen increases, but the ductility decreases gradually. The reliability index of the bearing capacity limit state of CGC members should be improved in the design. Due to the large deformation of CGC, the stirrup is more important for the restraint of CGC column deformation, so increasing the stirrup ratio will be an effective method to improve the mechanical performance of CGC column. When calculating the bearing capacity of the CGC column, the parameters α and β of the equivalent rectangular stress block should be corrected according to the change of coal gangue replacement ratio.