钙铝水滑石在水泥基材料中的氯离子固化行为研究

Chloride Ions Binding of Calcium-Aluminum Hydrotalcite in Cementitious Material

目的研究硝酸根型钙铝水滑石(CALN)的制备与性能,并探究其掺量对水泥净浆力学性能和氯离子固化性能的影响。方法将模拟孔溶液中浸泡前后的CALN样品分别进行X射线衍射分析、综合热分析;并取浸泡过CALN的模拟孔溶液进行棕色环试验;对CALN掺量为0%、1%、2%、3%、4%的水泥净浆试块进行力学性能测试;基于力学性能测试得到CALN的最佳掺量,并进行电通量与氯离子固化量试验。结果自制CALN的物相与硝酸根插层钙铝水滑石标准卡片(PDF#89-6723)匹配;模拟孔溶液中浸泡后其物相为Friedel盐,且溶液中存在硝酸根离子,实现了氯离子与硝酸根离子的交换;CALN掺量为3%的水泥试块在各个龄期强度发展最优,28 d强度达到64.94 MPa;其电通量下降了27.3%;在浓度为0.5~0.7 mol/L的氯化钠溶液中,其固化氯离子能力提升了15.7%~25.2%。结论制备的CALN具有高效、快速、稳定的氯离子交换行为与固化能力;水滑石在水泥中的最佳掺量为3%,能显著提高水泥的固化氯离子能力。

The purpose of this paperis to study the preparation and properties of nitrate calcium aluminum hydrotalcite(CALN),and to explore the influence of its mass content on the mechanical properties of cement paste and chloride ion binding properties.X-ray diffraction analysis and comprehensive thermal analysis of the CALN samples before and after immersion in the simulated hole solution were carried out;and the simulated hole solution after CALN soakedwas tested for brown ring experiment;The mechanical properties of cement paste test blocks with CALN content 0%,1%,2%,3%,and 4%were tested,and then the optimal dosage of CALN was obtained;The experiments on electric flux and chloride ion curing amount were carried out.The phase of the self-made CALN matches the standard card of calcium-aluminum hydrotalcite with nitrate intercalation(PDF#89-6723);After immersing in the simulated pore solution,the phase is Friedel salt,and there are nitrate ions in the solution,which realizes the exchange of chloride ions and nitrate ions;The cement test block with 3%CALN mass content has the best strength development at each age,and the 28 d strength reaches 64.94 MPa;Its electric flux decreased by 27.3%;in addition,in a sodium chloride solution with a concentration of 0.5 mol/L to 0.7 mol/L,its ability to solidify chloride ions increased by 15.7%to 25.2%.The prepared CALN has efficient,fast and stable chloride ion exchange behavior and curing ability;The optimal mass content of hydrotalcite in cement is 3%,which can significantly improve the cement′s ability to cure chloride ions.