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Electrical resistivity measuring techniques: (a) two-point uniaxial method; and (b) four-point (Wenner probe) method

Electrical resistivity measuring techniques: (a) two-point uniaxial method; and (b) four-point (Wenner probe) method

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Electrical resistivity measurement can be used for performance-based evaluation of concrete as an alternative to other tests methods that provide an indication of the concrete’s ability to resist chloride ion penetration. Several techniques have been developed and studied for measuring the electrical resistivity of concrete, including the bulk elec...

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Context 1
... determined with the aid of an equivalent circuit model representing the electrical properties of concrete and the electrode-concrete interface. Based on the proposed models, different measurement techniques have been developed, including two-point uniaxial and four-point (Wenner probe) techniques. Schematics of these test methods are shown in Fig. ...
Context 2
... this technique, the concrete sample is placed between two electrodes (usually two parallel metal plates) with moist sponge contacts at the interfaces to ensure a proper electrical connection ( Fig. 2(a)). An AC current is applied, and the drop in the potential between the electrodes is measured. Equation (2) describes the geometrical factor used in the uniaxial ...
Context 3
... widely accepted setup is the Wenner probe, where the four electrodes are located in a straight line and equally spaced. The two inner electrodes measure the electrical potential V created when the exterior electrodes apply an AC current I to the concrete (Fig 2(b)). For a semi-infinite homogenous material, the geometrical factor is defined by Eq. (3) ( 3) where a is the distance between the electrodes (equally spaced); and γ is the dimensionless geometry correction factor. ...

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Citations

... The appropriate conductivity and relative dielectric constants are allocated to the aggregate, rubber, and mortar in the numerical simulation of the mesoscale model of the rubberized concrete, as shown in Table 1, respectively. This provides to compute and assess the internal potential distribution [46][47][48][49][50][51]. ...
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Rubberized concrete is a multiphase composite material that is made up of aggregate, rubber, and mortar. The applied voltage is often considered as an influencing factor when studying its properties, such as chlorine ion impermeability and resistivity. However, the electric potential distribution inside the rubberized concrete under applied voltage conditions needs to be studied in depth. In this paper, mesoscale research was conducted on the effect of the rubber geometry on the electric potential of rubberized concrete. The results reveal three points. First, The inclusion of rubber has a certain attenuation or blocking impact on overall and local potential propagation, and the effect varies depending on the content, shape, and size of the rubber. Second, when the rubber contents and particle heights are equal, cube rubber outperforms octahedron and spherical rubber in terms of the potential barrier effect. Third, for the same rubber content, the smallest rubber size provides the best barrier effect of electric potential. The potential difference decreases as the rubber size increases, although the law is not fixed.
... It is important to note that except for the study carried out by Ghahari, Ghafari and Lu [23], all the other studies measured the electrical conductivity of the samples using a DC method. It has been reported in the literature that fast-switching DC or AC is the ideal method for measuring the electrical conductivity of cementitious materials [27,28], because cementitious materials are inclined to store electrical charge and thus generate an undesirable polarization effect if electrical resistance is measured using DC signals [29]. Apart from that, a combined effect of a resistive voltage component and a Seebeck voltage component is observed due to subjecting the sample to elevated temperatures. ...
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Thermoelectric materials enable the direct conversion of thermal to electrical energy. One application of this is ambient heat energy harvesting where relatively stable temperature gradients existing between the inside and outside of a building could be utilized to produce electricity. Buildings can thus change from energy consumers to energy generators. This could ultimately help reduce the surface temperatures and energy consumption of buildings, especially in urban areas. In this paper, research work carried out on developing and characterizing a cement-based thermoelectric material is presented. Cement-based samples are doped with different metal oxides (Bi2O3 and Fe2O3) to enhance their thermoelectric properties, which are defined through their Seebeck coefficient, electrical conductivity and thermal conductivity. The study also discusses the positive impact of moisture content on the electrical conductivity.
... However, Shiyu et al. found that the electroneutrality of the pore solution and the surface properties of the hydration product influence the chloride transport in ternary blended cementitious systems more than their pore structure [15]. Additionally, electrical resistivity had an impact on chloride transport in cementitious systems, particularly when it came to the movement of chloride by electrical potential [16][17][18][19][20]. The approach fully excludes the impacts of other negatively charged species in the pore solution, making it the most disadvantageous of the electrically accelerated processes [21]. ...
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The objective of this study is to analyse the mechanical and durability properties of a high-performance mortars based on low grade kaolin clay and the effect of electrical conductivity and pore microstructure on the chloride penetration resistance. A total of six mixes were prepared with binary and ternary binders in which a high volume of cement was replaced by low-grade calcined kaolin clay, fly ash and limestone powder. The percentage of kaolinite in the clay used from the Southeast European region was less than 20%. The variations in compressive strength and chloride transport coefficient were analysed experimentally and related to the pore structure and electrical conductivity. Compressive strength, chloride migration and diffusion coefficients, and bulk conductivity were determined using mortar samples, while the pore size distribution was determined by mercury intrusion porosimetry (MIP) on hardened cement paste after 7,28, and 90 days of curing. To understand the capillary absorption of these mixtures, sorptivity indices were measured after 28 and 90 days. The experimental characteristics of the pore size distribution, such as mean pore entry radius (r 0.5), permeable porosity (P), capillary porosity (ɸ), and critical pore diameter (rc), were calculated using the cumulative data of the intruded volume as a function of pressure obtained by MIP. In addition, the extrusion-intrusion curve was used to calculate the pore entrapment fraction (α) and the degree of inter-connectivity of the pore structure. The evolution of pore structure parameters was monitored for up to 90 days and their effects on strength and chloride penetration were studied in detail. The results showed that all mixes (even those with low kaolinite content) can be used in high performance cement systems and the pore structure has a limited effect on chloride penetration.
... In the dry state, the electrical resistivity is 10 12 Ωmm, but in the wet state, concrete behaves like a semiconductor and has a resistivity of 10 5 Ωmm [7]. The electrical resistivity of concrete depends on the w/c ratio, pore size distribution, pore fluid conductivity and temperature [8]. According to [9,10], the electrical resistance of the W14 fastening system on the B70 2.6 W-60 concrete sleeper is greater than 5 kΩ. ...
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Since the rails serve as a current conductor from the vehicle to the electrical substation, the rail fastening system must have a certain electrical resistance to prevent current from leaking from the rail to the sleeper. The resistance can be determined using a laboratory test described in the standard EN 13146_5-2012. This standard specifies a test procedure for determining the electrical resistance of the fastening system and sleeper under wet conditions. The test uses a multimeter to record current and voltage over time. One rail is connected to the positive pole of the laboratory rectifier and the other rail is connected to the negative pole. The current from the rectifier flows into the rail and through the fastening system and sleeper to the other rail and back to the source. This paper describes the laboratory measurement of electrical resistance performed on a W-14 fastening system and a concrete sleeper. The measurement was performed at the Faculty of Civil Engineering, University of Zagreb, within the project "Development of the elastic fastening system DIV".
... The test is normally conducted on the bottom surface near the reinforcement in the concrete specimen in order to find out the cover chloride resistivity. Resistivity in the concrete decreases with an increase in the size and number of pores or cracks and also with an increase in the chloride ion concentration [22,23] . Specimen resistivity against chloride ions was measured in terms of electrical resistivity (kiloΩ-cm) by measuring the ratio between potential differences in two inner electrodes and the current flow in two outer electrodes. ...
... Specimen resistivity against chloride ions was measured in terms of electrical resistivity (kiloΩ-cm) by measuring the ratio between potential differences in two inner electrodes and the current flow in two outer electrodes. The test results depend on the cement paste and aggregate properties of concrete: where R es represents the resistivity of the concrete cover, 2π represents the constant equivalent for the concrete specimen, O represents the potential differences between two inner electrodes, I c represents the current flowing in the concrete using two outer electrodes and d represents the equal interval between electrodes (see Figure 6(a)) [22][23][24] . The test should be conducted in such a manner as to avoid the reinforcement in concrete as much as possible (see Figure 6(b)). ...
... The effect of depassivation in the reinforcement does not have any significant effect on the resistivity readings, although a slight increase in decrement rate for the 15 mm cover in comparison to the 30 mm clear cover was observed at a later period after depassivation of the rebar started. This is due to lesser clear cover and the development of minute cracks resulting in the quicker ingression of chloride ions [22] . ...
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The reliable monitoring of the progression or extent of pitting-type corrosion in reinforced concrete members requires great effort due to non-uniformity. This paper presents a new approach for measuring the progression and extent of pitting-type (non-uniform) corrosion in reinforced concrete members by combining both non-destructive testing with optical fibre sensing results. Accelerated corrosion on the reinforcement (rebar) of the specimen was produced artificially using an alternate wetting and drying process in sodium chloride solution with 7.5% and 10% concentrations. The multimode optical fibre patch cords were attached to the reinforcement in three different arrangements in a single specimen (normal optical patch cord and loose and firm microbend patch cords). Intensity loss in a propagating light travelling inside an optical fibre takes place due to the development of pressure from surrounding concrete on the fibre from rust formation (corrosion). The study also describes the effect of corrosion in half-cell potentiometer, chloride ion resistivity and indirect pulse velocity readings obtained from the specimen. A later study found that the use of an optical microbend sensor is an effective alternate method for determining the starting time of initial depassivation in the reinforcement and validates it using half-cell potentiometer values. The study also developed models to predict overall mass loss in the rebar due to corrosion using combined non-destructive testing methods.
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... The Er behavior depends on diverse features such as the cement, the inorganic additives, the water-cement rate, and the porosity of the structure. 21 For this study, the Er was measured using an electrical resistance meter according to Layssi et al. 22 Table 3 depicts the resistivity markers test described in Guzmán Torres. 23 Figure 1 shows the device used for testing electrical resistivity on concrete specimens in this research, and the Er is given by ...
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Innovations are being developed with different additives in concrete mixtures to enhance their performance under certain conditions. This work models the split tensile strength through the electrical resistivity using a machine learning (ML) algorithm in different concrete mixtures. One of the most frequent non-destructive tests used on concrete is electrical resistivity (Er) for the simplicity of taking measurements on concrete elements. ML involves methods that provide solutions to advanced problems employing computational algorithms. This research employs a support vector regression algorithm, which might predict the split tensile strength value using a non-destructive test. The outcomes of this research exhibit a high correlation between electrical concrete resistivity and split tensile strength of over 90%. The support vector regression algorithm achieves an accuracy of over 93% in the forecasting task. Of note is that the modified concrete contains starch as an addition to prove its performance compared to conventional concrete.
... These ions remain trapped in the hardened cement pastes and can be affected by any passing current. In fact, the direct current (DC) has been avoided in the electrical resistivity measurement devices to avoid the polarizing effect of the ions in the cement pastes [20]. Polarizing effect of the DC on hardened cement pastes was reported previously. ...
... In addition, to record the produced piezoelectric voltage, wet sponges were placed between the faces of the specimen and the neoprene pads, which were then connected to a data acquisition (DAQ) device using insulated lead wires. The wet sponges were utilized to ensure maximum contact between the surface of the specimen and the electrode, this choice of electrodes was adopted from the two-points uniaxial bulk resistivity testing procedure [20]. The loading frequency was 1 Hz and the data acquisition rate was 50 Hz. ...
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This study investigates an innovative polarizing technique that can enhance the piezoelectric behavior of Portland cement pastes. This technique utilizes a direct current (DC) during the initial curing stage to polarize the cement paste. The simplicity of this technique makes it attractive for future real-world applications, especially in the structural health monitoring (SHM) field. The scope of this work is to study the effect of the mixing water, and different curing voltages on the piezoelectric behavior of a total of 24 specimens. 12 specimens were prepared by mixing the cement with deionized (DI) water and other 12 specimens with tap (T) water. 3 T specimens and 4 DI specimens were not cured under the effect of DC to serve as reference. The rest of the specimens were cured under different voltages, namely: 5 V, 10 V, and 25 V. All the specimens were tested under cyclic compression loading that oscillates between 3 kN and 12 kN, and the produced piezoelectric voltage was recorded. The cyclic loading was applied on the faces that are parallel to the polarizing direction for all the treated specimens. The results show that the DC curing of cement pastes produces denser specimens. In addition, the DC curing increases the produced piezoelectric voltage for the T specimens. The g 33 when compared to the reference specimens demonstrated an increase of approximately 163%, 134%, and 143% when cured under the effect of 5 V, 10 V, and 25 V, respectively. However, mixing with deionized water approximately eliminates the piezoelectricity of the cement paste.
... Changes in the temperature and characteristics of the pore solution during the rapid chloride penetration (RCP) test are mostly responsible for the nonlinear relationship between electrical resistivity and RCP values. For quantification, a link between electrical resistivity and diffusion coefficient would be more acceptable [48]. A typical test setup for the electric resistivity is shown in Figure 4. ...
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Corrosion study of conventional reinforcement in concrete has been accorded wider importance in the last few decades based on the losses occurring in monitoring concrete structures. It is well known that the presence of chloride ions is one of the most significant factors contributing to the corrosion of reinforcing steel. Practically, it is observed that in the marine environment, the activating substances such as chlorides that penetrate the steel can counteract the passivity locally when the electrolyte is highly alkaline. The concrete cover is changed chemically when chloride ionspenetrate into the material, whereupon the pore solution is neutralized. Based on numerous studies, it is evident that steel fibers and glass fibers have less impact on cracked sections in a chloride environment and can oppose chloride infiltration. Glass fibers, when exposed to repeated freeze and thaw conditions, protect the passive layer. This review article highlights the corrosion behavior of reinforced concrete involving various factors such as cracking behavior, transportation, electric conductivity, resistivity, and diffusion of chloride ions in the presence of steel and glass fibers.
... In order to analyze the dispersion quality, a resistivity test was carried out on the mortar specimens using the uni-axial method of measurement [38] as shown in Figure 2. A potentiostat/galvanostat provided by Gamry Instruments was used and the galvanostatic pulse method was adopted to measure the electrical resistance of the material. The current was injected from the electrodes, the instantaneous drop in voltage between two current peaks was measured as shown in Figure 3, and the corresponding electrical resistance was calculated using Ohm s law. ...
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This study focuses on different techniques for dispersing Multi-Walled Carbon Nanotubes (MWCNTs) in cementitious materials. The impact of dispersion is observed through electrical resistivity and mechanical properties of cementitious composites. Two contents (0.5 and 1% by mass of cement) of MWCNTs are investigated and three different techniques were used to disperse CNTs in water by sonication: (i) pristine, P-CNT, (ii) functionalized carbon nanotubes by classical approach (dispersive agent, D-CNT), and (iii) by an innovative approach (annealing, A-CNT). Self-sensing response of the material under cyclic compressive loading is measured with Wheatstone Bridge (WSB) circuit. Results showed a detrimental effect of dispersive agent on the resistivity and mechanical properties of cementitious composites irrespective of the content of CNTs. However, the impact of P-CNT and A-CNT on the reduction of mechanical properties is slight. With the use of 1% content of A-CNTs, a stable resistivity response of the material is observed irrespective of the saturation degree. This indicates that content higher than 1% of A-CNTs is not required for the development of smart cementitious composites for structural health monitoring (SHM). The test results of self sensing measurements indicate a poor repeatability of the electrical response for plain mortar under each loading cycle while, stable response is noticed with specimens incorporating 1% of A-CNTs. The maximum variation in fractional change in voltage (FCV) shown by plain mortar is 6.3% indicating high electrical resistance of plain mortar, while in case of mortar containing 1% A-CNTs, variation in FCV is 35% indicating lower electrical resistance and better sensitivity of the material.