Durability of Gangue Concrete under Freeze-thaw and Dry-wet Cycles

[Objective] In order to study the influence mechanism of changing the number of freeze-thaw cycles and the coarse aggregate replacement rate on the mechanical properties, frost resistance and sulfate erosion resistance of ordinary concrete and coal gangue concrete, [Method]this article focuses on analyzing key indicators such as the loss rate of compressive strength, mass loss rate and dynamic elastic modulus loss rate. [Result] Compressive strength of coal gangue concrete decreases significantly with an increase in the number of freeze-thaw cycles, specifically decreasing by an average of 30% for every 50 freeze-thaw cycles. Compared to ordinary concrete, coal gangue concrete exhibits more pronounced degradation effects at freeze-thaw action. The freeze-thaw damage model constructed based on the dynamic elastic modulus loss rate demonstrates higher fitting accuracy and effectively characterises the evolutionary patterns of the macro-mechanical properties of coal gangue concrete. [Conclusion]In dry-wet cycle tests, all specimens exhibited progressive damage characteristics. As the coal gangue content increased, the durability performance showed a regular decline. At the same number of dry-wet cycles, adding more gangue reduces durability. Specifically, R60, R80, and R100 were deemed structurally damaged when their compressive strength and corrosion resistance coefficients decreased to 75% after 60 dry-wet cycles.