Spragg R, Jones S, Bu Y, Lu Y, Bentz D, Snyder K, Weiss J
Purdue University, West Lafayette, IN.
Oregon State University, Corvallis, OR.
Cem Concr Compos. 2017 May;79:94-105. doi: 10.1016/j.cemconcomp.2017.02.003. Epub 2017 Feb 20.
Electrical tests have been used to characterize the microstructure of porous materials, the measured electrical response being determined by the contribution of the microstructure (porosity and tortuosity) and the electrical properties of the solution (conductivity of the pore solution) inside the pores of the material. This study has shown how differences in concentration between the pore solution (i.e., the solution in the pores) and the storage solution surrounding the test specimen leads to significant transport (leaching) of the conductive ionic species between the pore solution and the storage solution. Leaching influences the resistivity of the pore solution, thereby influencing electrical measurements on the bulk material from either a surface or uniaxial bulk resistance test. This paper has three main conclusions: 1.) Leaching of conductive species does occur with concentration gradients and that a diffusion based approach can be used to estimate the time scale associated with this change. 2.) Leaching of ions in the pore solution can influence resistivity measurements, and the ratio of surface to uniaxial resistivity can be used as a method to assess the presence of leaching and 3.) An estimation of the magnitude of leaching for standardized tests of cementitious materials.
电气测试已被用于表征多孔材料的微观结构，所测量的电响应由微观结构（孔隙率和曲折度）以及材料孔隙内溶液的电学性质（孔隙溶液的电导率）共同决定。本研究表明，孔隙溶液（即孔隙中的溶液）与围绕测试样品的储存溶液之间的浓度差异，会导致导电离子物种在孔隙溶液和储存溶液之间发生显著的迁移（浸出）。浸出会影响孔隙溶液的电阻率，从而影响通过表面电阻测试或单轴体积电阻测试对块状材料进行的电学测量。本文有三个主要结论：1.）导电物种的浸出确实会随着浓度梯度发生，并且可以使用基于扩散的方法来估计与这种变化相关的时间尺度。2.）孔隙溶液中离子的浸出会影响电阻率测量，表面电阻率与单轴电阻率之比可作为评估浸出是否存在的一种方法。3.）对胶凝材料标准化测试的浸出量进行估计。
