Conductivity/activation energy relationships for cement-based materials undergoing cyclic thermal excursions
Conductivity/activation energy relationships for cement-based materials undergoing cyclic thermal excursions
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DOI：
10.1007/s10853-014-8669-2
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发表时间：
2015-02
影响因子：
4.5
通讯作者：
W. McCarter;G. Starrs;T. Chrisp;P. Basheer;S. Nanukuttan;S. Srinivasan
中科院分区：
文献类型：
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作者：
W. McCarter;G. Starrs;T. Chrisp;P. Basheer;S. Nanukuttan;S. Srinivasan
通过在−30/+70 °C的扩展温度范围内进行多次加热和冷却循环，研究了一系列混凝土混合物（含和不含辅助胶凝材料（SCM））的电导率。当以Arrhenius格式呈现时，实验结果显示在热循环的低温端的滞后效应，并且在含有补充胶凝材料的那些混凝土中，在较高的水/粘合剂比率下，滞后效应在整个温度范围内是明显的，随着热循环次数的增加变得更加明显。可以清楚地识别在冻结和解冻点的凹陷，并用于估计孔颈和孔腔半径。本文提出了一种用电导率测量来估算冻结孔隙水体积比的简化方法。混凝土试件的电导率和活化能与水胶比、SCM类型、孔隙水的物理状态和热循环制度有关。
The electrical conductivity of a range of concrete mixes, with and without supplementary cementitious materials (SCM), is studied through multiple cycles of heating and cooling over the extended temperature range −30/+70 °C. When presented in an Arrhenius format, the experimental results display hysteresis effects at the low-temperature end of the thermal cycle and, in those concretes containing supplementary cementitious materials at higher water/binder ratios, hysteresis effects were evident over the entire temperature range becoming more discernible with increasing number of thermal cycles. The depression in both the freezing and thawing point could be clearly identified and was used to estimate pore-neck and pore-cavity radii. A simplified approach is presented to evaluate the volumetric ratio of frozen pore water in terms of conductivity measurements. The results also show that the conductivity and activation energy of the concrete specimens were related to the water/binder ratio, type of SCM, physical state of the pore water and the thermal cycling regime.