Assessment of Electrical Resistivity and Oxygen Diffusion Coefficient of Cementitious Materials from Microstructure Features

Abstract

A newly proposed modified non-contact electrical resistivity measurement was used to test the resistivity of concrete and cement mortar. The oxygen diffusion coefficients of concrete and mortar were determined by a gas diffusion measurement, and the capillary porosity of concrete and cement mortar was measured by mercury intrusion porosimetry (MIP) measurement. The obtained electrical resistivity and capillary porosity results were verified with other researchers’ data, the measured electrical resistivity results can be estimated by a simple equation from the capillary porosity results. The obtained oxygen diffusion coefficient results were quantitatively correlated with capillary porosity and electrical resistivity measurement results. The proposed equations can be practically used to assess the electrical resistivity and oxygen diffusion coefficient.

Influence of Sulphate Attack on Properties of Modified Cement Composites

“…The durability of cement composite is determined not only by its physical and mechanical properties, but also by its electrical characteristics, and can ensure the operational reliability of materials. Studies aiming to stabilize the dielectric properties and the resistance to sulphate attack of electrically insulating concrete have been successfully performed in recent decades [1][2][3]. However, the corrosion resistance to sulphate attack of electrically conducting composites has not been sufficiently studied.…”

“…As the most widespread and hybrid type of destructive process, the degree of material resistance to sulphate corrosion is considered to be the main criterion for the effectiveness of waterproofing [7][8][9]. Hybridity relates to the fact that sulphates in water increase the solubility of the components of cement matrix, and also initiate the development of exchange reactions between the components of cement matrix and a sulphate-containing solution [2,6,7].…”

“…Studies of synthesized pure samples of ettringite and thaumasite, and hydration products formed in the structure of cement matrices [2,7], have shown that it is not possible to draw unambiguous conclusions about the volume of these minerals [2,6,7,10].…”

“…Most researchers describe the effect of sulphate attack as a process in which the sulphate ions in water, when penetrating into concrete, significantly increase the solubility of the components of the solid phase of concrete, which accelerates the corrosion of the first type [2,6]. Simultaneously, the development of exchange reactions occurs with the substitution of the cation in the sulphate for the calcium ion from the concrete, which initiates corrosion of the second type [2,6].…”

“…The proposed model focuses on the analysis of three aspects: the process of sulphate ion transfer [7]; chemical reactions caused by the process of sulphate corrosion [6]; and the combination of the hydraulic pressure of the solution and the chemical reaction between the sodium sulphate solution and the components of solid phase of concrete [2].…”