Experimental analysis of coupled water and chloride transport in cement mortar
Experimental analysis of coupled water and chloride transport in cement mortar
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DOI：
10.1016/s0958-9465(03)00102-1
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发表时间：
2004-08
影响因子：
10.5
通讯作者：
R. Černý;Z. Pavlík;P. Rovnaníková
中科院分区：
文献类型：
--
作者：
R. Černý;Z. Pavlík;P. Rovnaníková
本文对水泥砂浆中水和氯的耦合传输进行了实验分析。初始水分含量相当于 45% 相对湿度的样品接受单侧氯化钠水溶液吸收，并在三个选定的时间间隔内测定水分分布和氯化物浓度分布。在评估测量的水分分布和氯化物浓度分布时，采用扩散模型。使用两种常用于水分剖面分析的方法，即双积分法和 Matano 法，将水分扩散率确定为水分含量的函数，将氯离子扩散系数确定为氯离子浓度的函数。两个系数的最高值是通过Matano方法获得的，对应于溶液暴露24 h的曲线，Matano方法获得的最低值是168 h，双积分法获得的结果介于两者之间。为了比较而进行的以蒸馏水作为渗透液的补充实验没有显示出这一特征。据观察，氯化物溶液在初始时间段内的水输送比蒸馏水更快，而在后期则较慢。因此，观察到的水分扩散率和氯化物浓度系数计算表观值的差异归因于 Cl- 和 Na+ 离子比水分子更快地吸附在孔壁上的事实。这种效应应包含在使用离子结合等温线的数学模型中。
Coupled water and chloride transport in cement mortar is analyzed experimentally in the paper. Samples with initial moisture content corresponding to 45% relative humidity are subjected to one-sided sodium chloride-in-water solution uptake, and moisture profiles and chloride concentration profiles are determined in three chosen time intervals. In the evaluation of measured moisture profiles and chloride concentration profiles, diffusion model is employed. Moisture diffusivity is determined as function of moisture content and chloride diffusion coefficient as function of chloride concentration using two methods commonly used for analysis of moisture profiles, namely the double integration method and the Matano method. The highest values of both coefficients are obtained by Matano method for the curves corresponding to 24 h exposure to the solution, the lowest values by Matano method for 168 h, the results obtained by double integration method are in between. The complementary experiments with distilled water as penetrating liquid performed for the sake of comparison do not show this feature. It is observed that water transport in the initial time period is for the chloride solution faster and in later times slower than for distilled water. Therefore, the observed differences in the calculated apparent values of moisture diffusivity and chloride concentration coefficients are attributed to the fact that Cl−and Na+ions are adsorbed on the pore walls faster than water molecules. This effect should be included into the mathematical models using ion binding isotherms.