纳米碳酸钙对水泥石氯离子结合量的影响

Effect of Nano-Calcium Carbonate on Chloride Ion Binding Amount of Cement Stone

混凝土孔溶液中的自由氯离子转化为结合氯离子可有效降低沿海、盐湖地区钢筋混凝土结构中的钢筋的腐蚀程度。以纳米碳酸钙掺量和氯离子浓度为变量,研究了纳米碳酸钙对水泥石氯离子结合量的影响,采用电位滴定法测定结合氯离子含量,根据氯离子等温吸附理论绘制结合氯离子与自由氯离子的拟合关系曲线来分析水泥石的氯离子结合能力,通过XRD和热重分析研究水泥石的氯离子结合机理。结果表明:纳米碳酸钙的掺入提高了水泥石的氯离子结合量,当其掺量达3%(质量分数)时,水泥石的氯离子总结合量最大;随着氯离子浓度的提高,掺纳米碳酸钙的水泥石氯离子结合量会相应增加;纳米碳酸钙的掺入可以加快水泥水化,促进C-S-H凝胶和Friedel’s盐的生成,有利于水泥石的氯离子物理吸附和化学结合。

The conversion of free chloride ions into bound chloride ions in the concrete pore solution can effectively reduce the corrosion of reinforcing steel in reinforced concrete structures in coastal and salt lake areas.The effect of nano-calcium carbonate on chloride ions binding amount of cement stone was investigated.Potentiometric titration was used to determine the content of bound chloride ions,and the chloride ion binding capacity of cement stone was analyzed by plotting the fitted relationship curve between bound and free chloride ions according to chloride ion isothermal adsorption theory.The chloride ion binding mechanism of cement stone was analyzed by XRD and thermogravimetry analysis.The results show that the admixture of nano-calcium carbonate increases the chloride ion binding amount of cement stone,and the total bound chloride ions content is the largest when its admixture reaches 3%(mass fraction).With the increase of chloride ion concentration,the chloride ion binding amount of nano-calcium carbonate doped cement stone increases accordingly.The admixture of nano-calcium carbonate could accelerate the hydration of cement and promote the generation of C-S-H gel and Friedel’s salt,which is beneficial to the chloride ion physical adsorption and chemical binding of cement stone.