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<p>The use of coal gangue as aggregate in concrete is an important pathway for the large-scale recycling of solid waste; however, its mechanical behavior under fire-induced high temperatures remains insufficiently understood, which limits its safe application in fire-resistant structures or post-fire rehabilitation. In this study, high-temperature uniaxial compression tests were conducted on 20 groups of coal-gangue concrete prism specimens to systematically investigate the independent and coupled effects of exposure temperature (25&#xa0;°C, 300&#xa0;°C, 500&#xa0;°C, 800&#xa0;°C) and coal-gangue replacement ratio (0–100%) on their stress–strain responses. The results indicate that, at the same exposure temperature, the elastic modulus decreases continuously as the replacement ratio increases, the axial compressive strength first decreases and then increases, and the peak strain gradually rises. Specimens with high replacement ratios exhibit higher residual strength after high-temperature exposure. At a constant replacement ratio, the elastic modulus decreases sharply with increasing temperature, dropping to 20–30% of its room-temperature value at 500 °C and to only about 10% at 800 °C; the axial compressive strength shows a temporary increase at 300&#xa0;°C but decreases significantly beyond 500 °C; and the peak strain continues to increase. The failure mode transitions from oblique shear at room temperature to an X-shaped pattern after high-temperature exposure, with severe fragmentation observed at 800 °C. Based on the test data and the segmented constitutive model proposed by Professor Guo, a modified stress–strain model was developed by incorporating fire temperature (<i>T</i>) and coal-gangue replacement ratio (<i>r</i>) as key variables in the parameter formulations. The proposed model demonstrates good agreement with the experimental curves and provides a more targeted theoretical basis for performance assessment and repair design of coal-gangue concrete structures after fire exposure.</p>

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Experimental investigation on the influence of fire exposure on the uniaxial compressive stress–strain response of gangue concrete

  • 期刊论文

  • 发表日期：

    2026年4月18日

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  • Zhengyao Yu,
  • Bo Wen,
  • Yadong Li,
  • Guanyi Gao,
  • Huaizheng Wang

摘要

The use of coal gangue as aggregate in concrete is an important pathway for the large-scale recycling of solid waste; however, its mechanical behavior under fire-induced high temperatures remains insufficiently understood, which limits its safe application in fire-resistant structures or post-fire rehabilitation. In this study, high-temperature uniaxial compression tests were conducted on 20 groups of coal-gangue concrete prism specimens to systematically investigate the independent and coupled effects of exposure temperature (25 °C, 300 °C, 500 °C, 800 °C) and coal-gangue replacement ratio (0–100%) on their stress–strain responses. The results indicate that, at the same exposure temperature, the elastic modulus decreases continuously as the replacement ratio increases, the axial compressive strength first decreases and then increases, and the peak strain gradually rises. Specimens with high replacement ratios exhibit higher residual strength after high-temperature exposure. At a constant replacement ratio, the elastic modulus decreases sharply with increasing temperature, dropping to 20–30% of its room-temperature value at 500 °C and to only about 10% at 800 °C; the axial compressive strength shows a temporary increase at 300 °C but decreases significantly beyond 500 °C; and the peak strain continues to increase. The failure mode transitions from oblique shear at room temperature to an X-shaped pattern after high-temperature exposure, with severe fragmentation observed at 800 °C. Based on the test data and the segmented constitutive model proposed by Professor Guo, a modified stress–strain model was developed by incorporating fire temperature (T) and coal-gangue replacement ratio (r) as key variables in the parameter formulations. The proposed model demonstrates good agreement with the experimental curves and provides a more targeted theoretical basis for performance assessment and repair design of coal-gangue concrete structures after fire exposure.