Degradation processes in reinforced concrete structures that affect durability are partially controlled by transport of aggressive ions through the concrete microstructure Ions are charged and the ability of concrete to hold out against transfer of ions greatly relies on its electrical resistivity Hence, a connection could be expected between electrical resistivity of concrete and the deterioration processes such as increase in permeability and corrosion of embedded steel Through this paper, an extensive literature review has been done to address relationship between concrete electrical resistivity and its certain durability characteristics These durability characteristics include chloride diffusivity and corrosion of reinforcement as these have major influence on concrete degradation process Overall, there exists an inverse or direct proportional correlation between these parameters Evaluated results, from measuring the concrete electrical resistivity, can also be used as a great indicator to identify early age characteristics of fresh concrete and for evaluation of its properties, determination of moisture content, connectivity of the micropores, and even condition assessment of in-service structures This paper also reviews and assesses research concerning the influential parameters such as environmental conditions and presence of steel rebar and cracks on measuring electrical resistivity of concrete Moreover, concrete resistivity concept, application, and its various measurement techniques are introduced

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Electrical Resistivity of Concrete for Durability Evaluation: A Review

Many agencies are interested in using a rapid test method for measuring the electrical properties of concrete (i.e., the resistivity or conductivity) because the electrical properties can be related to fluid transport (e.g., ion diffusion). The advantage of electrical testing is that it is relatively easy to perform, and the test method is relatively fast (it takes less than a minute). Over the past century, many studies have investigated different approaches for measuring electrical properties. This paper describes the variability associated with measuring the bulk resistivity along the longitudinal axis of a cylinder after placing electrodes on either end. A multi-laboratory evaluation was performed at ten laboratories. Data from this evaluation provided variability data for 12 concrete mixtures at testing ages of 28, 56, and 91 days. Information on the variability is important in the development of precision and bias statements for standard test methods. In addition, this work discusses how the resistivity results obtained from this test can be correlated with surface resistivity measurements made using a Wenner probe. Linear agreement was noticed between the Wenner test and the measurement through the cylinder, but with a factor confirmed by previous research by Morris et al. (“Practical Evaluation of Resistivity of Concrete in Test Cylinders Using a Wenner Array Probe,” Cem. Concr. Res., Vol. 26, 1996, pp. 1779–1787). Additionally, the effect of electrode resistance is discussed, and for high resistivity concrete such as that used in much transportation infrastructure, this effect appears to be negligible; however, it can be accounted for easily.

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Variability Analysis of the Bulk Resistivity Measured Using Concrete Cylinders

This paper discusses a series of electrical measurements made on cementitious mortars containing water–NaCl solutions (0–23.3% concentration by mass) over temperatures in the range of 23 °C to −35 °C. Electrical impedance spectroscopy, acoustic emission, and thermal measurements were made during cooling and heating to detect phase changes and resulting damage. The influence of the degree of saturation (DOS) and NaCl solution concentrations are examined. Three phase changes were detected: (1) eutectic phase change (∼−24 °C), (2) ice/water phase change (∼−4 °C to −4 °C), and (3) chemical phase change (∼−4.5 °C to −5.5 °C). While the resistivity is highly dependent on changes in temperature, a drastic increase in resistivity is observed during freezing. Additionally, a comparison of specimens above and below the critical DOS (i.e., the DOS required for damage to occur) shows that resistivity measurements may able to be used to quantify damage.

Electrical response of mortar with different degrees of saturation and deicing salt solutions during freezing and thawing

Electrical properties can be important indicators for durability of cement-based porous materials (CBPMs). This study seeks to deepen the understanding of the effect of water saturation degree on the electrical properties of CBPMs. Taking into account the joint conduction effects of the phases of pore solution and surface adsorption, and the determination by the quadratic deviation factor, we analyze the experimental data in the literature and evaluate the important parameters, i.e. the percolation threshold and Archie exponent. The contribution of the adsorbed phase to the total electrical properties is minor in high water saturation degree region, and then becomes heavily important as water content approaches the threshold. More thoughtful interpretation of the electrical properties of CBPMs should be conducted to correlate the threshold and exponent data to the micro- and pore structures and the transport properties.

The effect of water saturation degree on the electrical properties of cement-based porous material

Electrical resistivity is increasingly being used as a nondestructive technique to evaluate the durability properties of concrete While concrete resistivity is temperature dependent, the effect of temperature that may cause misleading results has thus far not been properly taken into account In this paper, an extensive investigation was carried out to study the effect of temperature on the electrical resistivity of water-saturated and unsaturated concrete specimens Resistivity measurements were performed at temperature cycles ranging from 10 to 45°C (50 to 113°F) The profiles of resistivity versus temperature were found to conform to the Arrhenius law Furthermore, the activation energy (the amount of thermal energy required to promote a mole of the ions in the concrete pore solution to carry a current flow under an electric field) was found to be dependent on the resistivity of the concrete Based on these findings, a methodology was developed to normalize the resistivity values measured at different temperatures to the values at a reference temperature (for example, 21°C [70°F]), and to predict the resistivity variations due to temperature changes Compared with existing methods, the method proposed in this paper is more accurate for normalizing the temperature effect on concrete resistivity

Normalization of Temperature Effect on Concrete Resistivity by Method Using Arrhenius Law

Concrete resistivity is directly related to relative humidity (RH) and is also affected by temperature. In this paper, a theoretical discussion about how these two factors affect resistivities of concrete and mortar is provided. Moreover, experimental results on sensorized mortar probes are presented and correlated to analytical models of temperature and humidity influences. All measurements were performed under controlled conditions. Temperature, RH, and resistivity were measured simultaneously in a particular zone of the probes. Temperature scanning was performed over short periods of time (approximately 1 h) and the probes were covered with waterproof paraffin each time for constant humidity content. This was feasible as all sensors were embedded. Water contents were ensured during the experiment by weighting the probes. Conclusions on the applicability of these techniques, their advantages, and limitations, and correlation to Archie and Arrhenius laws of the results are made.

J. Fullea García

Papers

Influence of temperature and humidity on Portland cement mortar resistivity monitored with inner sensors