Deterioration characteristics of coal gangue concrete under the combined action of cyclic loading and freeze-thaw cycles

Coal gangue is a kind of solid waste. Adding coal gangue as aggregate into concrete can realize the resource utilization of solid waste. The deterioration law of coal gangue concrete under the combined action of cyclic loading and freeze-thaw was studied by macro and micro methods. The mass loss, relative dynamic elastic modulus loss, and compressive strength loss of specimens under the combined action were analyzed. The microscopic morphology and pore structure deterioration law of gangue concrete were investigated by scanning electron microscopy and mercury compression test. The quantitative relationship between the pore structure and compressive strength damage was established. The results show that with the increase of cyclic loading and freeze-thaw cycles, the mass of the specimen first increases and then decreases. The relative dynamic elastic modulus and compressive strength gradually decrease. The larger fractal dimension indicates the higher complexity of the pore structure. The fractal dimension decreases with the increase of cyclic loading times and freeze-thawing, implying that the pore structure gradually deteriorates under the combined action. The regression effect between compressive strength damage and composite pore structure parameters and fractal dimension is evident, describing the quantitative relationship between compressive strength damage and pore structure under the combined action of cyclic loading and freeze-thaw cycles. • The mechanical properties gradually deteriorate under the combined action. • The larger fractal dimension indicates the higher complexity of the pore structure. • The deterioration degree of coal gangue concrete is greater than ordinary concrete. • Establishing the pore structure-strength damage multiple regression model.