【摘要】 通过干湿循环硫酸盐侵蚀试验和SEM微观结构表征，研究了不同粉煤灰掺量对混凝土在硫酸盐侵蚀环境下的劣化机制及耐久性能演化规律。基于抗压强度损伤量和粉煤灰掺量影响系数，构建了混凝土耐久寿命预测模型。结果表明：在干湿循环硫酸盐侵蚀过程中，粉煤灰混凝土的质量变化率、孔隙率和抗压强度均呈现先增大后减小的非线性变化特征，其中30次循环时达到峰值，90次循环后出现显著劣化；硫酸盐侵蚀过程中钙矾石的持续生成是导致混凝土结构劣化的主要因素，而适量粉煤灰的掺入可有效优化混凝土孔隙结构，提高基体密实度，从而增强其抗硫酸盐侵蚀能力；当粉煤灰掺量为20%时，混凝土表现出最优的抗硫酸盐侵蚀性能，其预测耐久寿命较普通混凝土延长41%,表明粉煤灰的掺入对改善混凝土长期耐久性能具有显著效果。研究结果可为硫酸盐侵蚀环境下粉煤灰混凝土的耐久性设计与寿命预测提供理论依据和技术支持。更多还原

【Abstract】 Through sulfate attack tests under dry-wet cycles and scanning electron microscopy( SEM) microstructural characterization, the degradation mechanisms and durability evolution of concrete with different fly ash contents in sulfate environments were investigated. A durability lifespan prediction model for concrete was established based on compressive strength degradation and fly ash content influence coefficients. The results indicated that during sulfate attack under dry-wet cycles, the mass variation rate, porosity, and compressive strength of fly ash concrete exhibit nonlinear variation characteristics — initially increasing and then decreasing, peaking at 30 cycles and showing significant deterioration after 90 cycles. The continuous formation of ettringite during sulfate attack is the primary factor causing structural deterioration, while an appropriate fly ash content(20%) optimizes pore structure, enhances matrix compactness, and improves sulfate resistance. Concrete with20% fly ash demonstrates optimal sulfate resistance, with its predicted durability lifespan extends by 41% compared to ordinary concrete,confirming the significant role of fly ash in enhancing long-term durability. This study provides theoretical and technical support for the durability design and lifespan prediction of fly ash concrete in sulfate environments.更多还原