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<p>Foamed lightweight concrete has gained increasing attention in cold region infrastructure construction due to its excellent thermal insulation properties and reduced structural loads. However, the durability performance under freeze-thaw cycles remains a critical concern that limits its widespread application. This study investigates the durability enhancement mechanism of fiber-reinforced foamed lightweight concrete subjected to freeze-thaw cycles through advanced microstructural analysis techniques. Specimens with polyacrylonitrile fibers and alkali-resistant glass fibers were prepared with a water-to-solid ratio of 1.75 and a target wet density of 6.5&#xa0;kN/m<sup>3</sup>, then subjected to five different curing environments including standard curing, water immersion, salt immersion, freeze-thaw cycles, and salt-freeze-thaw coupling. Industrial computed tomography (CT) scanning and nuclear magnetic resonance techniques were employed to quantitatively characterize the pore structure evolution during 75 freeze-thaw cycles (− 20&#xa0;°C to 20&#xa0;°C, 8&#xa0;h per cycle). Results demonstrate that fiber reinforcement significantly improves the pore structure by reducing the proportion of critical pores (1-10&#xa0;μm), thereby enhancing freeze-thaw resistance. The compressive strength retention rate of fiber-reinforced specimens reached 78.5% after 75 cycles under salt-freeze-thaw coupling conditions, compared to 45.2% for unreinforced specimens. CT analysis reveals that fiber networks effectively constrain pore expansion and interrupt seepage channels, with water seepage depth serving as a reliable indicator of freeze-thaw damage progression. The study reveals that fibers create a three-dimensional skeletal network that redistributes freeze-thaw stresses and mitigates damage accumulation. These findings provide theoretical foundation for the application of fiber-reinforced foamed lightweight concrete in cold regions and offer new insights into durability assessment methods based on microstructural characteristics.</p>

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Durability Performance of Fiber-Reinforced Foamed Lightweight Concrete under Freeze-Thaw Cycles

  • 期刊论文

  • 发表日期：

    2025年11月19日

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  • Youqiang Qiu,
  • Yang Liu,
  • Liujun Zhang,
  • Zhanqi Wang,
  • Panpan Guo

摘要

Foamed lightweight concrete has gained increasing attention in cold region infrastructure construction due to its excellent thermal insulation properties and reduced structural loads. However, the durability performance under freeze-thaw cycles remains a critical concern that limits its widespread application. This study investigates the durability enhancement mechanism of fiber-reinforced foamed lightweight concrete subjected to freeze-thaw cycles through advanced microstructural analysis techniques. Specimens with polyacrylonitrile fibers and alkali-resistant glass fibers were prepared with a water-to-solid ratio of 1.75 and a target wet density of 6.5 kN/m3, then subjected to five different curing environments including standard curing, water immersion, salt immersion, freeze-thaw cycles, and salt-freeze-thaw coupling. Industrial computed tomography (CT) scanning and nuclear magnetic resonance techniques were employed to quantitatively characterize the pore structure evolution during 75 freeze-thaw cycles (− 20 °C to 20 °C, 8 h per cycle). Results demonstrate that fiber reinforcement significantly improves the pore structure by reducing the proportion of critical pores (1-10 μm), thereby enhancing freeze-thaw resistance. The compressive strength retention rate of fiber-reinforced specimens reached 78.5% after 75 cycles under salt-freeze-thaw coupling conditions, compared to 45.2% for unreinforced specimens. CT analysis reveals that fiber networks effectively constrain pore expansion and interrupt seepage channels, with water seepage depth serving as a reliable indicator of freeze-thaw damage progression. The study reveals that fibers create a three-dimensional skeletal network that redistributes freeze-thaw stresses and mitigates damage accumulation. These findings provide theoretical foundation for the application of fiber-reinforced foamed lightweight concrete in cold regions and offer new insights into durability assessment methods based on microstructural characteristics.