干湿循环下煤矸石混凝土孔结构特性及抗氯离子侵蚀机理

氯离子侵蚀是影响混凝土耐久性的重要因素。通过干湿循环试验,研究了煤矸石混凝土的抗氯离子侵蚀性能,分析了煤矸石体积取代率(0%、20%、40%、60%)对氯离子浓度分布和表观扩散系数的影响。通过压汞试验,测定了煤矸石混凝土的孔结构参数,通过计算其孔隙体积分形维数,研究了孔结构对煤矸石混凝土抗氯离子侵蚀性能的影响。结果表明:随着煤矸石掺量的增加,自由氯离子的浓度先减小后增加,而表观扩散系数先增加后减小;煤矸石掺量为40%时,混凝土密实性最好,孔隙体积分形维数最大;与未添加煤矸石的混凝土相比,掺量40%的煤矸石混凝土氯离子浓度最低,此时抗氯离子侵蚀性能最好,且表观扩散系数下降35.68%。

Pore Structure Characteristics and Chloride Ion Corrosion Resistance Mechanism of Coal Gangue Concrete under Drying-Wetting Cycles

Chloride ion corrosion is an important factor affecting the durability of concrete.The chloride ion corrosion resistance of coal gangue concrete by drying-wetting cycles test was studied, and the effect of coal gangue volume substitution rate (0%, 20%, 40%, 60%) on the chloride ion concentration distribution and apparent diffusion coefficient was analyzed. The pore structure parameters of coal gangue concrete were determined by mercury intrusion porosimetry, and the fractal dimension of pore volume was calculated. The influence of pore structure on chloride ion corrosion resistance of coal gangue concrete was studied. The results show that with the increase of the content of coal gangue, the free chloride ion concentration decreases first and then increases, while the apparent diffusion coefficient increases first and then decreases. Compared with the concrete without coal gangue, when the content of coal gangue is 40%, the compactness of concrete is the best and the fractal dimension of pore volume is the largest. At this moment the chloride ion concentration is the lowest and the chloride ion corrosion resistance of coal gangue concrete is the best. The apparent diffusion coefficient of chloride ion decreases by 35.68%.