不同干湿制度下氯离子在混凝土中的传输特性

Transport Characteristics of Chloride Ion in Concrete under Dry-Wet Cycles

设计了8种干湿循环侵蚀制度,定量分析了不同侵蚀制度同混凝土中氯离子传输深度、氯离子含量分布规律、表面氯离子含量、氯离子扩散系数、对流区及氯离子传输效率之间的关系.结果表明:干湿循环加速氯离子的传输仅限于一定范围;不同干湿制度下,表面氯离子含量随干湿比的增加而有所增加;干湿循环下混凝土中对流区的出现具有时间性;随着干湿循环周期的增加,对流峰值以幂函数增加,且干湿比越大越有利于氯离子峰值浓度的积累;干湿循环制度不同,但干湿循环1个周期的时间相同且干湿比为5:1时,氯离子向混凝土内的传输效率最高.

Different dry-wet cycle system for analyzing the transport characteristics of the chloride ion in concrete was designed. Eight kinds of cyclic erosion system was also designed, then the influences of differ- ent cyclic conditions on the transport depth of chloride ion, the distribution of chloride ion concentration, surface chloride ion concentration, chloride ion diffusion coefficient, convection zone and chloride ion transport efficiency in concrete were investigated. The following conclusions are drawn from the test re- sults：the acceleration effect of wet and dry cycles on the chloride ion transportation is limited to a certain extent; for the different wet and dry systems, the chloride ion concentration increases with the increase of dry-wet ratio; the appearance of the convection zone in concrete under wet and dry cycles show time de- pendent; with the increase of the cycle period, convection peak gradually increases in the form of power function, and the increase of the dry-wet ratio is conducive to the accumulation of peak concentration; in the same period of the cycle, when dry-wet ratio is 5 ~ 1 the highest transport efficiency of the chloride ion in concrete is achieved.