氯盐浸泡的水泥基材料的表面氯离子浓度(英文)

Chloride Ion Concentration on the Surface of Cement-Based Materials in Chloride Solutions

水泥基材料的表面氯离子浓度(cs)是Fick’s第二定律寿命预测模型的1个重要参数,它通过将Fick’s第二定律与氯离子浓度分布拟合而得到。当水泥基材料浸泡在一定浓度的氯盐溶液中时,水泥基材料的cs和浸泡溶液的氯离子浓度(c)之间的关系仍未得到很好的理解。一些发表的文献表明cs要高于c,Nagataki将其称为浓缩现象。本文研究了cs和c之间的关系,并探索了其机理。将普通Portland水泥、80%(质量分数,下同)水泥+20%粉煤灰和60%水泥+40%矿渣3种5 mm厚的硬化水泥浆体薄片分别浸泡于氯离子浓度为0.15 mol/L,0.5 mol/L,1 mol/L的3种氯化钠溶液中,浸泡35 d和120 d后,采用压滤法将硬化水泥浆中的孔溶液压滤出来,测量其氯离子浓度,并与c进行对比。结果表明:c较低时(0.15 mol/L),压滤法得到的孔溶液的氯离子浓度约比c高30%;当c较高时(>0.5 mol/L),压滤法得到的孔溶液的氯离子浓度与浸泡溶液浓度相当。分析认为双电层是产生该现象的关键因素。

Chloride ion concentration on the surface of cement-based materials（cs） is an important parameter of the Fick＇s second law service life prediction model.The cs can be obtained by fitting chloride ion profile based on the Fick＇s second law.When ce-ment-based materials are in contact with chloride solutions,the relation between the cs and the chloride ion concentration（c） of the exposure solution could not be well understood.Some previous work indicated that the cs is higher than the c.This is called conden-sation phenomenon by Nagataki.This paper investigated the relation between the cs and the c,and explored the corresponding mechanism.Three types of cement discs with the thick of 5 mm [ordinary Portland cement（OPC）,20%（in mass,the same below） fly ash＋80% OPC,40% slag＋60% OPC] were immersed in sodium chloride solutions with the c of 0.15 mol/L,0.5 mol/L and 1 mol/L,respectively.After 35 and 120 d,the pore solutions of the cement discs were squeezed out by a pore expression method.The chloride ion concentrations were measured,and compared to the c of exposure solution.The results show that,the c obtained by the pore ex-pression method is 30% higher than that of exposure solution at 0.15 mol/L.At c0.5 mol/L,the c was equal to that of the exposure solution.The effect of electrical double layer could be responsible for this phenomenon.