Effect of chemical admixtures on concrete’s electrical resistivity

Abstract

Purpose The purpose of this paper is to verify the influence of superplasticizer and air entrainment admixtures (AEs) in the electrical resistivity of concrete. Design/methodology/approach Ten different types of concrete have been studied. Three levels of superplasticizer and air AEs have been used (0.20, 0.35 and 0.50 per cent). Concrete samples were cast and the electrical resistivity was monitored at the ages of 28, 63 and 91 days. Compressive strength and density tests have also been executed. Findings The superplasticizer admixture presented an optimal level of 0.35 per cent that significantly increased the electrical resistivity. The air AEs at the same dosage caused a considerable decrease in the electrical resistivity. The concrete with air AEs showed highest resistivity/MPa ratio. Research limitations/implications The results should be carefully extrapolated for other materials and admixtures. Practical implications The usage of chemicals admixture in concrete is extremely common nowadays. However, only a few authors have studied the impact of such materials on the concrete’s electrical resistivity. Since many other researchers have already correlated electrical resistivity with other concrete’s properties, such as strength, setting time and corrosion probability, it is important to better understand how superplasticizers and air-entraining agents, for instance, impact the resistivity. Originality/value The vast majority of studies only tested the resistivity of cement paste or mortar and usually for short period of time (up to 28 days), which seems not to be adequate since the cement reaction continues after that period. This paper fills this gap and studied the impact of admixture on concrete and for a period of 91 days.

Correlations between water absorption, electrical resistivity and compressive strength of concrete with different contents of pozzolan

“…Revista ALCONPAT, 9 (2), 2019: 152 -166 Correlations between water absorption, electrical resistivity and compressive strength of concrete with different contents of pozzolan Bem et al (2018), chemical admixtures might affect the electrical properties of the concrete. Therefore, no chemical admixtures were used.…”

Corrosion performance of steel reinforcement in concrete admixed with magnesium chloride and sulphate

“…However, several researchers (Azarsa and Gupta, 2017;Hornbostel et al, 2013;Kurda et al, 2019;Medeiros-Junior et al, 2019;Mendes et al, 2018;Stefanoni et al, 2018) have studied the effect of different factors, such as w/cm ratio, cement type, supplementary cementitious materials, degree of hydration, temperature, relative humidity, size and type of aggregate, curing condition, on electrical resistivity. These studies also reported the various correlations of concrete properties such as compressive strength (de Bem et al, 2018;Medeiros-Junior et al, 2019;Wei et al, 2012), corrosion (Ahmad, 2014;Hornbostel et al, 2013;Yu et al, 2017) with the electrical resistivity of concrete. From the current study and earlier literature, it confirms that w/cm ratio, cementitious material type (expressed as calcium to aluminium content (Ca/Al) content) and compressive strength Figure 8 Histogram and frequency distribution function of corrosion data for steel reinforcement in concrete contaminated with magnesium chloride and magnesium chloride plus magnesium sulphate for w/cm ratio 0.51 Figure 9 Corrosion current density values of reinforcing steel in OPC and MK blended concrete contaminated with chlorides and sulphates are the deciding factors for the electrical resistivity of the concrete.…”

Correlation between concrete strength properties and surface electrical resistivity

“…Electrical resistivity can be defined as the ability of a material to withstand the electrical current passage. Therefore, resistivity is the inverse of conductivity [9]. In the concrete, electrical resistivity is a property that characterizes the difficulty with which the ions move in the concrete aqueous phase, subjected to an electrical field [18].…”

“…However, there are few studies that suggest other applications for the surface electrical resistivity test. Some authors, such as Lübeck et al [7], Chen et al [8], Bem et al [9] and Mendes et al [10], observed that the concrete resistivity increases as the compressive strength increases, whereas Medeiros-Junior and Lima [11] report that electrical resistivity measurements can be used to predict the compressive strength of Portland cement pastes.…”