The paper presents the results of a study of the effect of internal moisture on the electrical conductivity of cement composites with expanded graphite. Cement pastes with different content of expanded graphite were prepared for measurement. The electrical conductivity was determined by using impedance spectroscopy at different degrees of water saturation. The results of the impedance spectroscopy were presented in Nyquist plots. On the basis of the obtained Nyquist plots, electrical equivalent circuits were fitted for different water saturation. Capacitance and resistance were calculated from the fitted equivalent circuits. Additionally, DC four-probe resistance measurements were carried out. The results showed that internal moisture affects the electrical conductivity of composites not only for a low amount of expanded graphite but also for the content in the percolation zone. For composites with expanded graphite with percolation zone (4 and 5 wt%), the dominant conduction mechanism changed from electron to ionic with moisture content. This change is observed as a change in the nature of the Nyquist plot from a vertical line to a semicircle. Internal moisture does not affect the conductivity of cement composites with expanded graphite higher than the percolation threshold.

中文翻译：

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阻抗谱测定内部水分对膨胀石墨水泥复合材料电导率的影响


本文介绍了内部水分对膨胀石墨水泥复合材料电导率影响的研究结果。制备不同膨胀石墨含量的水泥浆进行测量。通过在不同水饱和度下使用阻抗谱测定电导率。阻抗谱的结果以奈奎斯特图呈现。在获得的奈奎斯特图的基础上，针对不同的水饱和度拟合了等效电路。电容和电阻是根据拟合的等效电路计算的。此外，还进行了直流四探针电阻测量。结果表明，内部水分不仅影响低含量的膨胀石墨，而且影响渗流区的含量，从而影响复合材料的电导率。对于具有渗滤区（4 和 5 wt%）的膨胀石墨的复合材料，随着水分含量的变化，主要传导机制从电子变为离子。这种变化被观察为奈奎斯特图的性质从垂直线到半圆的变化。内部水分不会影响膨胀石墨水泥复合材料的电导率高于渗滤阈值。