Monitoring Hydration In Lime-Metakaolin Composites Using Electrochemical Impedance Spectroscopy And Nuclear Magnetic Resonance Spectroscopy
Monitoring Hydration In Lime-Metakaolin Composites Using Electrochemical Impedance Spectroscopy And Nuclear Magnetic Resonance Spectroscopy
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DOI：
10.1180/claymin.2014.049.3.01
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发表时间：
2014-06
期刊：
影响因子：
1.5
通讯作者：
G. Pesce;C. Bowen;J. Rocha;M. Sardo;G. C. Allen;P. Walker;G. Denuault;M. Serrapede;R. Ball
中科院分区：
文献类型：
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作者：
G. Pesce;C. Bowen;J. Rocha;M. Sardo;G. C. Allen;P. Walker;G. Denuault;M. Serrapede;R. Ball
本文用电化学阻抗谱和核磁共振技术研究了偏高岭土(MK)与石灰的水力反应。试验在20℃、25℃和30℃下进行，石灰-MK浆料的质量比为10：1。通过28天的测试，可以确定EIS信号的相关变化，并使用热分析(TGA/DSC)、扫描电子显微镜(SEM)、压汞测孔仪(MIP)和单轴压缩测试对浆体进行表征。在较短的时间内(最多42小时)进行测试，可以更详细地研究在反应开始时形成的水力相。热分析结果证实了CSH、C4AH13和C3ASH6等水力化合物的形成，并显示了它们随时间的演化。MIP分析表明，与水力相的形成和转化有关的孔径分布发生了变化。阻抗响应随时间的变化与反应动力学有关。在反应的前42小时内，核磁共振信号的变化与氢氧化钙在孔道溶液中的溶解有关。总之，本文论证了核磁共振在石灰基材料水力反应研究中的重要性，以及EIS检测水力化合物的形成和氢氧化钙溶解过程结束的能力。
Abstract This paper describes a study of the hydraulic reactions between metakaolin (MK) and air lime using electrochemical impedance spectroscopy (EIS) and nuclear magnetic resonance spectroscopy (NMR). Tests were carried out at 20, 25 and 30°C on lime-MK pastes with 10:1 w/w ratio. Tests over 28 days allowed identification of relevant changes in the EIS signals and characterization of pastes using thermal analysis (TGA/DSC), scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP) and uni-axial compressive tests. Tests over shorter periods of time (up to 42 h) allowed more detailed studies of the hydraulic phases formed at the very beginning of the reactions. Results of thermal analyses demonstrate formation of hydraulic compounds such as CSH, C4AH13 and C3ASH6 and show their evolution over time. MIP analysis demonstrates changes in pore size distribution related to the formation and trasformation of hydraulic phases. Variations of impedance response with time are shown to be associated with reaction kinetics. Changes in the NMR signal within the first 42 h of reaction are shown to be associated with the dissolution of calcium hydroxide in the pore solution. Overall, this paper demonstrates the importance of NMR in the study of hydraulic reactions in lime based materials and the ability of EIS to detect the formation of hydraulic compounds and the end of the calcium hydroxide dissolution process.