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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 electrical resistivity of concrete refers to its ability to withstand the transfer of ions under an electrical field. Its level largely depends on the microstructural properties of concrete, including pore size, distribution, and connectivity (i.e., tortuosity) within the matrix [43,44]. As a performance-based parameter, electrical resistivity plays a crucial role in evaluating the durability and structural integrity of concrete. ...
Ensuring the durability of concrete pavements against chloride ingress is critical, yet the relationship between electrical resistivity and chloride penetration remains underexplored. This study evaluates the effectiveness of entrained air and fly ash in mitigating chloride ingress using an electrical resistivity model and surface resistivity tests. Concrete samples with varying entrained air contents (0% to 10%) and Class C or Class F fly ash underwent three-year ponding tests in temperature-controlled indoor water baths and outdoor CaCl2-NaCl brine solutions. The results indicate that lower entrained air contents led to a more rapid increase in resistivity, with concrete mixes incorporating Class C fly ash exhibiting 1.5 times greater resistivity gains than those with Class F fly ash. Surface resistivity tests revealed that reaction factors were 67% higher in specimens with 3.5% entrained air compared to 10.0%, while decreasing by 57% and 41% in concrete mixes containing Class F and Class C fly ash, respectively, across all chloride concentrations. Using back-calculated environmental factors, corrosion initiation potential in concrete pavements was projected for exposure periods of up to 50 years. These findings provide insights for optimizing entrained air and fly ash formulations to enhance pavement performance and durability.
... The bulk electrical resistivity of concrete is a crucial parameter with various applications, primarily in assessing and enhancing the durability and longevity of concrete structures [41][42][43]. It serves as an indicator of the concrete's ability to resist the penetration of chloride ions and other aggressive agents, with higher resistivity correlating to better corrosion resistance [44]. ...
Graphene nanoplatelet aggregates (GNAs) are a low-cost, low-quality alternative to graphene nanoplatelets (GNPs), characterized by their three-dimensional stacked structure and porous surface morphology. Despite their affordability, limited research has been conducted on the effects of GNAs in cementitious systems. This study investigates the impact of GNAs on hydration kinetics, phase assemblage, mortar consistency, mechanical strength, bulk electrical resistivity, water absorption, and pore solution pH. Mortar mixtures with 0%, 0.05%, and 1% GNAs by cement weight were prepared using a water-to-cement ratio of 0.42 and cured for 28 days. The results showed that GNAs had minimal influence on hydration kinetics, with no significant changes in hydration products detected by XRD and TGA analyses. Mortar consistency consistently decreased with increasing GNA content. At 0.05%, GNAs had no significant effect on compressive strength or bulk electrical resistivity, whereas 1% GNAs reduced compressive strength by 10%. Water absorption was significantly lower in specimens with 1% GNAs as well, while pore solution pH increased at this dosage. The findings of this study indicate that the incorporation of GNAs at a 0.05% replacement level does not inherently enhance cementitious properties but can influence specific behaviors, such as workability and water absorption, when used at 1% dosages.
... As a heterogeneous material, the porous characteristics of concrete contribute to its permeability, which is influenced by its pore structure, porosity, strength, curing conditions, and service environment [6,19]. A finer pore network with less connectivity leads to lower permeability, whereas a porous microstructure with a larger degree of interconnections results in higher permeability and generally reduced durability [20]. According to [19], gas permeability of ordinary concrete increase with porosity and water-binder ratio. ...
... In other words, the resistance to corrosion (i.e., chloride ion penetration) is higher for concretes with higher resistivity. Similar findings have been reported by other researchers [20,[39][40][41]. For mixture HO-0.6, which has a lower porosity (18.6%), a lower surface resistivity was recorded compared to mixtures CR-0.65 (porosity of 19.5%) and LA-0.65 (porosity of 19.1%). ...
... Thus, the chloride diffusion coefficient values also indicated the same chloride penetrability as indicated by surface resistivity measurements. This suggests that resistivity can indeed be used as a reliable technique to obtain the diffusion coefficient of concrete structures [20]. ...
Premature deterioration of reinforced concrete structures, often caused by chloride and carbonation-induced corrosion, significantly shortens service life. In many instances, signs of degradation such as cracks in the cover concrete appear within a few years of construction. This study evaluates the effect of mixture proportions on the durability-related properties of concrete. The results show that the non-carbonated concretes exceeded the porosity limits for exposure classes XC3 and XC4 by 24% to 38%. A reduction in porosity of about 16 to 23% was also observed in the fully carbonated zones. Furthermore, mixtures with higher compressive strength showed lower permeability and chloride penetration. An increase in aggregate content resulted in higher resistivity due to reduced porosity. It was found that 7 days of accelerated carbonation testing at 4% CO2 for the mixture with higher w/cm (CT-0.92) was equivalent to 1.5–2 years of natural exposure at 0.03–0.04% CO2, whereas the mixtures with lower w/cm ratios corresponded to about 2–7 months. Furthermore, mixtures CT-0.92 and LA-0.65 had lower alkali concentrations (0.28%–1.11%) than HO-0.61 and CT-0.71, which had higher K2O (up to 4.06%) and Na2O (up to 4.53%) levels, suggesting a higher potential risk for ASR. Also, the aggregates in mixtures CT-0.71 and HO-0.61 recorded higher reactive silica content (60–70%), suggesting a higher ASR risk. Additionally, mixture CT-0.92 was classified as non-reactive while the other mixtures were classified as potentially reactive with a pessimum effect (expansion ≥ 0.15%). The results also show that bond strength increases with an increase in strength.
... Regarding the feasibility of using this type of slag in specific structural elements, the results indicate that the concrete specimens containing EAF slag demonstrate exceptional mechanical properties, including a compressive strength of [35][36][37][38][39][40][41][42][43][44][45] MPa and an elastic modulus of up to 46 GPa, making them suitable for demanding applications such as bridge decks, marine structures, and high-rise buildings [9]. The high electrical conductivity observed in concrete containing this aggregate is a direct consequence of the formation of a conductive network through the interconnected iron oxide particles. ...
... The results indicate that replacing 50% of natural aggregate with EAF slag leads to increases in the compressive strength, tensile strength, and elastic modulus of concrete of 8.97%, 17.97%, and 5.05%, respectively. Furthermore, a 100% replacement of natural aggregate with EAF slag resulted in even more significant improvements, with increases of 30.90%, 35.71%, and 25.02% in compressive strength, tensile strength, and elastic modulus, respectively [11]. In another study conducted by Faleschini et al., the effect of utilizing electric arc furnace (EAF) slag as a building material in enhancing environmental sustainability was investigated. ...
... Electrical resistivity measurements have gained significant traction in recent years as a valuable tool for evaluating concrete properties. While standards for surface resistivity (AASHTO T358) [34] and volumetric resistivity (ASTM C1760) [35] exist, the development of standards for other measurement techniques, such as four-probe or half-cell methods, is still ongoing. Concrete durability is inextricably linked to its microstructure, particularly the pore size distribution, pore connectivity, and degree of saturation. ...
In recent years, there has been a growing interest in developing sustainable concrete alternatives that reduce reliance on natural aggregates and promote waste recycling. One promising approach involves the utilization of electric arc furnace slag (EAFS) as a fine aggregate replacement. This study aims to investigate the impact of EAFS on the mechanical properties, specifically compressive strength and electrical resistivity, as well as the durability of concrete. Given the importance of accurately estimating concrete performance in the durability domain, this study explores the application of gene expression programming (GEP) to predict the electrical resistivity of concrete containing EAFS. To achieve these objectives, a series of concrete mixes were prepared with EAFS replacement levels ranging from 0% to 100% at water-to-cement ratios of 0.3, 0.4, and 0.5. Experimental results indicated a decrease in compressive strength with increasing EAFS content, particularly at higher water-to-cement ratios. Conversely, electrical resistivity decreased significantly with higher EAFS replacement levels. To enhance durability, it is recommended to incorporate a pozzolanic material alongside EAFS. The GEP models developed in this study exhibited excellent performance in predicting the electrical resistivity of concrete containing EAFS. The high correlation coefficients obtained demonstrate the model’s accuracy and reliability. An accurate outcome is achieved by the model configured with 45 chromosomes, a head size of 15, and a multiplicative linking function. Given the strong correlation between electrical resistivity and other durability properties, such as permeability and corrosion resistance, the GEP model can be a valuable tool for optimizing concrete mixtures and predicting long-term performance in sustainable construction applications.
... The LR model aims to find a linear correlation between the input variables and the flexural strength of the 3D-printed beam, achieving a coefficient determination of 84.5%. The changes in electrical resistivity and permittivity over time do not follow a linear trend [50], suggesting that a linear model may not be the best for estimating the mechanical strength of 3D-printed structures, as indicated by the R 2 value. To find more complex patterns between the selected features and the flexural strength of 3D-printed beams, the SVR model with different kernels was employed. ...
The absence of formwork in 3D-printed concrete, unlike conventional mold-cast concrete, introduces greater variability in curing conditions, posing significant challenges in accurately estimating the early-age mechanical strength. Therefore, common non-destructive techniques such as the maturity method fail to deliver a generalized predictive model for the mechanical strength of 3D-printed structures. In this study, multiple machine learning (ML) algorithms, including linear regression (LR), support vector regression (SVR), and artificial neural network (ANN), were developed to estimate the early-age flexural strength of 3D-printed beams under varying curing conditions, utilizing data collected from embedded sensors. Six input variables were employed for the ML models, including relative permittivity, internal temperature, and curing method. For model development, 144 data points were collected from an extensive experimental study, and multiple statistical metrics were employed to evaluate the proposed models. The ANN model outperformed the other models in predicting early-age strength, achieving a coefficient of determination of 95.1%. Furthermore, the input variable analysis highlighted the curing method as the most influential factor affecting the strength of 3D-printed beams.
... Therefore, these mechanical results corroborate the porosity results (open and quantitative through SEM) that had a low pore content, making the matrix denser and increasing its mechanical properties. The microstructure of cementitious composites is directly related to their durability (Aguiar, 2018), since electrical resistivity is a non-destructive test and can be a method to evaluate their quality and durability (Layssi et al., 2015). The surface electrical resistivity of 28 days (Figure 10), 300 kΩ.cm, was well above 47.5 kΩ.cm (Karein et al., 2017), being in the range characterized as insignificant in terms of corrosion potential (BALESTRA et al., 2020). ...
The objective of this work is to evaluate the use of silica fume captured in bag filters on the mechanical and physical properties, durability and microstructure of a high-performance structural mortar. The mix ratio was defined through particle packing and the following properties were evaluated: compressive and flexural strength, water absorption, porosity, dynamic modulus of elasticity, electrical resistivity and microstructure. Mixture proportion through particle packaging promoted densification of the mortar, improving the mechanical properties and durability. As a result, the filler effect was maximized by particle packing, and the pozzolanic effect promoted the improvement of properties in the long term. It is concluded that it is possible to use waste from producing metallic silicon and iron silicon captured in bag filters as silica fume. Resumo O objetivo do trabalho é avaliar a utilização de sílica ativa capturada em filtros de mangas nas propriedades mecânicas, físicas, durabilidade e microestrutura de uma argamassa estrutural de alto desempenho. O traço utilizado foi definido por meio do empacotamento de partículas e as seguintes propriedades foram avaliadas: resistências à compressão e tração, absorção de água, porosidade, módulo de elasticidade dinâmico, resistividade elétrica e microestrutura. A dosagem pelo empacotamento de partículas promoveu densificação da argamassa, melhorando a resistência mecânica e a durabilidade. Consequentemente, o efeito filer foi maximizado pelo empacotamento de partículas e efeito pozolânico promoveu melhoria das propriedades a longo prazo. Os resultados indicam que que é possível utilizar os resíduos provenientes da produção do silício metálico e ferro silício captada em filtros manga como sílica ativa. Palavras-chave: Sílica ativa; Resíduos de silício metálico; Resíduos de ferro silício; Argamassas estruturais; Argamassas de alto desempenho.
... Figure 8 illustrates the relationship between electrical resistivity and compressive strength. The durability of concrete is primarily dependent on its compres- sive strength, which is influenced by factors such as the impermeable matrix of its microstructure, including pore size distribution and interconnection geometry (Layssi et al., 2015). The disparities in chemical and physical characteristics between the binding matrix and the foams in the binder might lead to an unequal dispersion of hydration products in the ultimate bulk specimens. ...
In recent years, mortar bricks or autoclaved aerated concrete (AAC), also known as foamed concrete, have been widely used as masonry wall materials. Foamed concrete, like bricks, can be produced by adding a foaming agent to achieve the desired weight and density, while meeting requirements for strength and durability. However, the search for sustainable construction materials has become imperative , including the use of waste materials to partially replace cement. The incorporation of SCM in the production of cement-based materials, such as foamed concrete, has a significant impact on reducing CO 2 emissions and promoting a sustainable environment. POFA, a secondary product derived from the palm oil industry that is typically left on the ground , poses environmental problems. Due to its good performance and pozzolanic reactions, POFA-based construction materials have great potential as alternatives to ordinary Portland cement. Unlike previous studies, this research evaluates the strength and durability of foamed concrete with variations in foam agent dosages, including finer particles of POFA (100μm) as a partial cement replacement. The study produced a total of 6 batches of foamed concrete, measuring compressive strength, porosity, water absorption, and electrical resistivity. Additionally, the research examined the correlation between compressive strength and porosity, as well as compressive strength and electrical resistivity. This study concludes that an ideal content of 10% POFA with a foaming agent-to-water ratio (fa/w) of 1/60 can achieve the best strength of foamed concrete. Furthermore, a partial cement replacement with 20% POFA could potentially increase the compressive strength to levels similar to those of normal foamed concrete (without POFA).
... Concrete Surface Resistivity A concrete surface resistivity test has been conducted to evaluate the chloride diffusion coefficient (D rcm ). The standard techniques to assess surface resistivity are two-point uniaxial and four-point techniques [12]. For this study, the four-point technique has been used. ...
The construction industry in Bangladesh is actively pursuing the goal of preserving the equilibrium between the amount of greenhouse gases (GHGs) produced and expelled from the atmosphere. An ideal way to reduce CO 2 emissions from concrete production is the utilization of industrial by-products like class F fly ash, slag, etc. as supplementary cementitious materials (SCMs). On the other hand, reducing the life cycle cost (LCC) through the extension of service life could also be an effective way to reduce the overall carbon footprint of any RC infrastructure, particularly in saline exposure. Higher service life ensures lesser repair work for a corroded marine RC element and eventually results in reduced CO 2 emission in the lifetime. Therefore, it is evident that producing concrete with proper proportions of SCMs and other mix parameters to achieve the desired service life can reduce both the initial and long-term carbon emission potential of an RC structure in saline exposures. With this end in view, a case study is presented where concrete mixes have been prepared using different binder types (both customized and commercially available composite blends) for a particular design strength commonly used in Bangladesh. The service life and repair frequency of an RC element made of considered concrete mixes have been predicted through the electrical resistivity of the mixes. LIFE-365 software has been used for the analysis. It has been found that commercially available CEM III and the blended mix of CEM I with 30% slag plus 20% fly ash exhibited prolonged corrosion initiation time, least repair requirements during the service life of 100 -years and consequently, lower LCC and overall CO 2 emissions as compared to other mixes used. The outcome of the study thus necessitates the inclusion of required policies and guidelines in local construction supply chains and practices to reduce embodied carbon of RC construction.
... In this context, resistivity measurements can be used to estimate pore size and connectivity. The lower the resistivity value read, the higher the corrosion content of the concrete [39,40]. AASHTO T 358-17 [41] categorizes concrete resistance level to chloride penetration based on the resulting electrical resistivity values, as seen in Table 2. ...
... The grouting and jacketing test specimens with a corrosion rate of about 30% differ in the average decrease in resistivity value of 21%. This occurs because pre-cracked loading produces cracks that create space in the interconnection of concrete structures, thus affecting the resistivity value [39]. The slope results of the linear regression of both conditions show almost the same value, showing no effect of pre-cracked loading on the relationship between resistivity and actual corrosion. ...
... The difference in resistivity increase is due to the closing of gaps or pores created by cracks with grouting mortar. The fewer pores in the concrete, the greater the resistivity value and the more difficult it is for chloride ions to reach the iron reinforcement [39]. The GRT 30 test specimen obtained the lowest result at 3.29 kΩ-cm. ...
Under extreme environmental conditions, concrete is often damaged, ranging from cracking to destruction caused by corrosion of steel reinforcement. Damage caused by steel corrosion must be repaired immediately to prevent the wider spread of steel corrosion. This study carried out grouting, jacketing, and self-healing concrete repairs. Encapsulated Bacillus subtilis bacteria were used to make self-healing concrete. The specimen was a reinforced concrete (RC) beam measuring 62x15x15 cm damaged by steel corrosion. The reinforcement in the concrete was subjected to accelerated corrosion with mass loss (corrosion levels) of 20%, 25%, and 30%. The concrete beams were subjected to pre-cracked loading to produce cracks, which were then repaired. This study utilised resistivity, one of the NDT methods, as a parameter to measure the quality of reinforced concrete. Additionally, flexural strength was tested to evaluate the quality of the repair. The results indicated a decrease in resistivity and flexural strength as the corrosion level increased. Grouting and jacketing repairs showed a positive correlation between resistivity and flexural strength, whereas self-healing concrete exhibited a negative correlation. Resistivity testing on these repairs is limited, making this research crucial.
... A microstructure characterised by smaller pores and reduced connectivity corresponds to diminished permeability. Conversely, a porous microstructure marked by a greater extent of interconnections translates to heightened permeability and an elevated propensity for chloride ingress in most cases (Layssi et al., 2015). Chloride penetrability classification (Thomas et al., 2018) based on bulk resistivity is presented in Table 4. ...
The growing demand for sand and the environmental impact of sand mining have prompted efforts to find sustainable alternatives. The Ministry of Environment, Forest, and Climate Change, Government of India, advocates for the use of M-sand and recycled sand in construction to reduce dependency on
natural sand. This study explores the potential of coal mine overburden (CMOB) sand as a substitute for natural sand in concrete production. Comprehensive tests, including chemical, petrographic, and physical analyses, were conducted to evaluate CMOB sand’s suitability. Concrete mixes with CMOB sand were tested for strength, workability, and durability. Results reveal that CMOB sand can fully replace natural sand without compromising
structural integrity. The concrete demonstrated excellent compressive strength, moderate workability, and strong resistance to carbonation, chloride penetration, and acid attacks. This highlights CMOB sand as an eco-friendly, effective alternative, reducing reliance on natural resources while ensuring
durable concrete applications.
