海水干湿交替区氯离子对混凝土侵入作用的现场检测和分析

为研究海水干湿交替区氯离子对混凝土结构的侵入规律，本文分别对作用时间为4年多和16年多的2个海港码头干湿交替区进行多次现场检测。考虑了混凝土的表层对流区深度，运用Fick第二定律对实测氯离子侵入资料进行拟合，研究了干湿交替区不同高程纯扩散区域的表面氯离子含量和氯离子扩散系数。根据该海区潮汐特征的统计资料计算得到不同高程的海水年浸润时间比例，研究了不同码头海水年浸润时间比例与平均表面氯离子含量和平均扩散系数之间的关系。结果表明，海水年浸润时间比例在0.3～0.5之间时，平均表面氯离子含量和平均氯离子扩散系数都较大，将可能对混凝土结构造成严重的侵蚀。本文引入海水年浸润时间比例，可以将干湿交替条件下的氯离子侵入规律应用到其它海域。

Field inspection on chloride ion intrusion effect of seawater in dry wet cycling zone of concrete structures

The inspection on chloride ion intrusion effect of seawater in dry wet cycling zone of concrete structures occurred to two harbor docks was carried out. The working durations of these docks were 4a and 16a respectively. Based on the Fick's second law the convective depth was taken into account and the surface chloride ion concentration and apparent diffusion coefficient in pure diffusion zone at different elevations of dry wet cycling zone were obtained by regression analysis on chloride ion intrusion profiles. The ratios of annual soakage time at different elevation were calculated according to the statistic result of tide characteristics. On this basis, the relationship between ratio of soakage time and average surface chloride ion concentration and the relationship between ratio of soakage time and average diffusion coefficient were obtained. The results indicate that both the average surface chloride ion concentration and average diffusion coefficient are very high when the ratio of annual soakage time is in the interval of 0.3 to 0.5,which may induce serious erosion of concrete structures.