Study on the axial compressive properties of iron tailing sand concrete columns under high temperatures

Abstract This study examined the impact of replacing natural sand with iron tailing sand on the axial compressive behavior of reinforced concrete columns under high temperatures. Fire tests with constant load heating were conducted to assess these effects. Experimental tests compared temperature–time curves, axial displacements, and fire‐resistance limits of reinforcement and concrete under fire exposure. The study also systematically analyzed how concrete strength grades (C40, C50) and iron tailing sand replacement ratios (0%, 50%, 100%) affect the axial compressive behavior of concrete columns at elevated temperatures. The results show that the bursting of concrete columns under fire increases with higher iron tailing sand replacement rates. No significant difference was found in the cross‐sectional temperature field distribution between iron tailing sand and natural sand concrete columns. The lower the replacement rate of iron tailing sand and the higher the concrete strength grade, the better the fire‐resistance limit of the reinforced concrete columns. For C40 concrete columns, the fire resistance limit decreases by 15.5% and 24.1% with 50% and 100% iron tailing sand substitution. As the concrete strength grade increases from C40 to C50, the fire resistance limit improves by 12.2% and 22.7% with 50% and 100% iron tailing sand substitution. This study also established temperature field and heat‐force coupling models for iron tailing sand concrete columns. Empirical equations were fitted for the fire resistance limit of these columns based on the slenderness ratio and axial compression ratio. These equations provide a theoretical basis for their fire‐resistant design.