海水环境粉煤灰混凝土结构耐久性现场检测与评估分析

对服役12年的华南某跨海大桥典型构件开展碳化性能、氯离子扩散性能等指标的耐久性检测,评估了海水环境下掺粉煤灰的高性能混凝土长期耐久性。研究表明:随高程的增加混凝土碳化深度逐渐增大,其中大气区浪溅区水位变动区,碳化作用对粉煤灰混凝土结构耐久性的影响较小;粉煤灰可显著提升实体结构混凝土抗氯离子侵蚀性能,粉煤灰高性能混凝土的氯离子扩散系数不大于0.40×10-12m2/s,比普通混凝土氯离子扩散系数降低了约6倍;利用规范计算了引桥承台混凝土中氯离子含量计算值,其计算值与实测值吻合较好,可用于实体工程混凝土结构的耐久性评估,评估结果显示采用粉煤灰高性能的桥梁典型构件满足100年设计使用寿命的要求。

Field test and evaluation analysis on durability of fly ash concrete structures in seawater environment

The durability of the carbonization-resisting and chloride ion diffusion property typical components of a cross-sea bridge in the south of China was evaluated at 12 years service life. Results show that the carbonization depth of concrete increases with the increaseof height level, and that atmospheric zone >splash zone >tidal zone. Carbonation has little effect on the durability of fly ash concrete structures. Fly ash can significantly improve the resistance to chloride ion erosion of concrete. The chlorine ion diffusion coefficient of fly ash concrete is not greater than 0.40×10-12m2/s, and is reduced by 6 times that of ordinary concrete. The calculation value of chloride ion content in concrete bridge abutment is calculated by using specifications. The calculated value agrees well with the measured value, and can be used to evaluate the durability of concrete structures. The evaluation results show that the typical components of the bridge with high performance fly ash meet the requirements of the design service life of 100 years.