Half-cell Potential Values Research Articles

Machine learning for predicting the half cell potential of cathodically protected reinforced cement concrete slabs subjected to chloride ingress

This research work predicts the Half Cell Potential (HCP) values of cathodically protected concrete slabs subjected to chloride ingress using machine learning techniques. Six classes of cathodically protected slabs were cast using centrally placed pure Magnesium (Mg) anodes and AZ91D of dimensions 1000 mm × 1000 mm x 100 mm. The input variables included are: distance of the point in x and y direction (Dist x and Dist y), Relative Humidity (RH), Temperature, Age of concrete in days, and the Class of slab. For each class, three slabs were cast and the average value of HCP was considered as output. Experimental values consisting of 80 HCP values per slab per day were collected for 270 days and were averaged to generate the prediction model. Linear regression, kernel ridge, stochastic gradient descent, support vector machine, decision tree, random forest, gradient boosting, and Light Gradient Boosting Machine (LGBM) machine learning models were used for validating the experimental dataset. Among the eight models tested, the LGBM consistently outperforms the others across all metrics. LGBM provides the highest R-squared score (0.9828), lowest Mean Square Error (0.0015), Root Mean Square Error (0.0386), and Mean Absolute Error (0.0220), a-10 index (0.8007), and a-20 index (0.8987) making it the preferred choice for this specific dataset and problem. The sensitivity analysis performed for the LGBM model showed that the ‘Age of concrete’ is the most influential input for predicting output, while 'Temperature' and 'RH' show lower significance and rest variables have negligible impact.

Utilizing Electrochemical Techniques for Assessing the Probability of Concrete Resistivity and Corrosion Potential in Reinforced Concrete Structures

Corrosion of reinforcing steel is a major durability issue for reinforced concrete structures exposed to aggressive environments. Early assessment of corrosion probability is important for effective maintenance planning. This study investigates the application of non-destructive electrochemical methods like concrete resistivity and half-cell potential measurement, along with integrated assessment and advanced techniques, for evaluating corrosion risk in reinforced concrete. Concrete specimens with and without Albizia amara resin coating were subjected to accelerated corrosion testing. Concrete resistivity and half-cell potential values showed an inverse correlation, with lower resistivity indicating higher corrosion risk. Resistivity and potential results for the coated samples exhibited intermediate values compared to the control and corroded samples, demonstrating the resin's partial passivating effects. Rebar diameter measurements before and after exposure confirmed corrosion led to reductions in diameter and cross-sectional area, which coating mitigated. Statistical analysis validated the significant impacts of original bar diameter and corrosion level on subsequent geometry changes. Mechanical testing of reinforcing steel bars found the control samples had the highest strength and ductility, while the coated bars exhibited properties closer to the controls than the corroded bars. The protective capabilities of the bio-based Albizia amara resin coating were validated through multipoint monitoring of material durability parameters. Overall, results demonstrated the effectiveness of integrated electrochemical testing with non-destructive techniques for comprehensive condition assessment and corrosion risk evaluation in reinforced concrete structures

Unveiling optimal half-cell potentials in RCC slabs through cutting-edge ANFIS, ANN and genetic algorithm integration

PurposeThe purpose of this study is to compare the prediction models for half-cell potential (HCP) of RCC slabs cathodically protected using pure magnesium anodes and subjected to chloride ingress.The models for HCP using 1,134 data set values based on experimentation are developed and compared using ANFIS, artificial neural network (ANN) and integrated ANN-GA algorithms.Design/methodology/approachIn this study, RCC slabs, 1000 mm × 1000 mm × 100 mm were cast. Five slabs were cast with 3.5% NaCl by weight of cement, and five more were cast without NaCl. The distance of the point under consideration from the anode in the x- and y-axes, temperature, relative humidity and age of the slab in days were the input parameters, while the HCP values with reference to the Standard Calomel Electrode were the output. Experimental values consisting of 80 HCP values per slab per day were collected for 270 days and were averaged for both cases to generate the prediction model.FindingsIn this study, the premise and consequent parameters are trained, validated and tested using ANFIS, ANN and by using ANN as fitness function of GA. The MAPE, RMSE and MAE of the ANFIS model were 24.57, 1702.601 and 871.762, respectively. Amongst the ANN algorithms, Levenberg−Marquardt (LM) algorithm outperforms the other methods, with an overall R-value of 0.983. GA with ANN as the objective function proves to be the best means for the development of prediction model.Originality/valueBased on the original experimental values, the performance of ANFIS, ANN and GA with ANN as objective function provides excellent results.

Ketahanan Korosi Baja Tulangan dalam Beton menggunakan Palm Oil Fuel Ash (POFA) dan Air Laut

POFA (palm oil fuel ash) and seawater have the possible to be used in concrete as an effort to reduce construction costs and environmental waste problems. POFA contains pozzolanic properties such as those contained in cement so it has the possible to be used as a mineral in concrete mixtures. Therefore, the use of POFA and seawater in concrete mixtures have the potential to be implemented, but it is obligatory to pay awareness to the potential for corrosion that also follows. This study aims to evaluate the use of POFA up to 20% as a replacement for cement and the effect of mixing seawater on the strength and corrosion of reinforcing bar in concrete. The compressive strength of concrete was evaluated by carrying out a compressive test on a cylindrical specimen with 100 mm in diameter and 200 mm in height at 7 days and 28 days of age. Furthermore, a concrete cylinder specimen with a diameter of 10 mm reinforcement was used to evaluate the potential for corrosion. Measurement of corrosion estimation using the half-cell potential (HCP) method based on ASTM C876-15. Test results show the use of up to 10% POFA to replace cement by mixing seawater and treated with fresh water has a high strength that is almost the same as normal concrete. The risk of corrosion is also not detected and proven by actual measurements of corrosion. Furthermore, HCP values more negative than -400 mV are predicted to experience corrosion in the reinforcement area above 10%.

Impermeability Evaluation Of Concrete With Fly Ash Aggregate And Prediction With Modelling

Concrete is the most synthesized material in construction sector which it has aggregate as one of its components. The use of natural aggregate in concrete preparation uses a significant amount of non-renewable resources and energy, having a significant environmental impact. Multiple research projects have been conducted to safeguard natural reserves, seeking a solution to the waste disposal issue, and reduce construction costs by utilizing waste materials. FA(Fly Ash) aggregate is one such material that can be a replacement for natural aggregate. Durability parameters of concrete with Fly Ash (FA) aggregate are studied in this work as an alternative for fine aggregate. In this study, 5 concrete mixes were prepared utilizing FA aggregate in percentage substitution of 0%, 10%, 20%, 30%, and 40% for each. The quantity of cement, compaction, curing rate, concrete cover, and porosity all influence the durability of the concrete. Concrete attributes such as strength in compression, retaliation to abrasion and half-cell potential were investigated. Durability parameters of the specimens were tested after 90-day curing. The results revealed that concrete with 30% FA aggregate had the highest compressive strength, improved resistance towards abrasion and least half cell potential values. Experimentation data were used to develop comprehensive prediction models by applying support vector machine (SVM) algorithm. The SVM model analyses R2 values with an accuracy of over 97%. As a result, we can use SVM to efficiently execute prediction modelling in construction area.

Effect of addition of sugarcane baggasse ash on half-cell potential of cathodically protected RCC structures subjected to chloride ingress

Sugar cane bagasse ash (SCBA) is a by-product generated from sugar boilers and alcohol factories. It mainly consists of amorphous silica, which makes it a suitable supplementary cementitious material (SCM), apart from providing an economically viable and environmentally sustainable solution. This is particularly true in Indian scenario, which is second largest producer of sugarcane. Ample literature is available which describe the strength and durability aspects of concrete containing SCBA. But, less literature is available on corrosion behavior of such concrete. In the present research, the effect of partial cement replacement by SCBA on the half cell potential (HCP) of reinforcements embedded in concrete is studied through twelve reinforced concrete slabs made of M20 grade and dimension 1000 mm X1000 mm X100 mm. The amount of SCBA in each slab was 20% by weight of cement, based on obtained experimental results of compressive and flexural strengths at 7, 28, 56 and 90 days. All the slabs were cathodically protected using pure Magnesium (Mg) anodes. Out of the twelve slabs, six slabs were subjected to 3.5% NaCl ingress while the remaining six acted as reference slabs with no chloride ions. The HCP were measured at 80 points on each slab for 280 days, to observe the trend of these values and were averaged for similar slabs. It could be concluded that the presence of SCBA significantly reduces the HCP values, thereby indicating lesser probability of corrosion. The HCP values were higher for slabs containing chloride ions. Thus, for structures subjected to marine atmosphere, a combination of incorporating SCBA and cathodic protection could be an effective solution to mitigate corrosion.

Durability properties of novel coating material produced by alkali-activated/cement powder

This paper presents a feasibility study on the use of alkali-activated/cement powder (AACP) paste as a potential coating material for improving the durability of structures and protecting buildings exposed to marine environments. The AACP was synthesized by geopolymer powder (GP), Portland cement (PC), and silica fume (SF). The water-to-binder ratio of 0.45 and sodium hydroxide solution of 2 M were used to activate the reaction products of the AACP paste. The experimental tests consisted of the retained compressive strength and weight change after exposure to 5 % sulfuric acid (H2SO4) solution, 5 % magnesium sulfate (MgSO4) solution, and tap water (H2O), and chloride migration coefficient (RCM). The corrosion probability of concrete reinforcement with surface treatment of deformed bar (DB) using the half-cell potential (HCP) test was also evaluated. Test results showed that the AACP paste exhibited superior durability to PC paste, as evidenced by its relatively low strength loss and weight change. In addition, the chloride diffusion coefficient of AACP pastes was 32.7 to 77.6 times lower than that of PC paste. For the corrosion probability of concrete reinforcement, the average HCP values of the AACP paste-treated-deformed bar were lower than those of the no-treated or PC paste-treated-deformed bar, especially for the AACP paste prepared by GP without PC.

Evaluating composite nanomaterials to control corrosion of reinforcing steel using different tests

There is limited research on the utilization of composite nanomaterials to control corrosion of reinforcing steel in concrete. Therefore, this work was initiated to evaluate the composite nanomaterials (zinc oxide and titanium dioxide) to control corrosion deterioration in reinforced concrete using different tests. The composite nanomaterials were utilized as coating cover over the reinforcing steel surface using two methods of nanofilms and nanoparticles. Fourteen reinforced concrete prisms (100 ×100×300 mm) with central reinforcing steel coated with nanocomposite were casted using w/c ratio of 0.45. After 28 days of moist curing, the prisms were exposed to an accelerated corrosion process using an electrical current supply. The ability of nanocomposite to control corrosion was evaluated using different tests including crack width, ultrasonic pulse velocity (UPV), half-cell potential (HCP) and pullout test. The experimental results showed that nanocomposite materials coated over the reinforcing steel surface significantly reduced the corrosion level of the reinforcing steel in concrete. The non-destructive tests (UPV and HCP) showed significant difference between the nanocoated and uncoated specimens. The damage index of the UPV of the corroded uncoated prisms showed higher values than those of the corroded coated prisms. The HCP values of the nanocoated prisms after corrosion showed significantly lower negative values than those of the control uncoated prisms. Moreover, prisms coated with nanocomposite revealed less corrosion crack width and attained higher ultimate bond load compared to the uncoated prisms. The composite nanolayer coated on the reinforcing steel surface showed higher performance to control corrosion compared to the single nanolayer coated on the reinforcing steel surface. Scanning electron microscopy images showed more homogeneous filling layers of the composite nanolayer coating compared to the single nanolayer coating.

Evaluating corrosion deterioration in self-compacted reinforced concrete beams and prisms using different tests

There is a limited reported research on the corrosion deterioration of self-compacted concrete (SCC) compared to conventional vibrated concrete (CVC). Therefore, this work represents a novel and innovative research to evaluate the corrosion deterioration of reinforcing steel in SCC compared to CVC using different tests. Sixteen reinforced concrete (RC) beams (100 × 150 × 1000 mm) and 16 RC prisms (100 × 100 × 400 mm) were casted using two w/c ratios (0.35 and 0.45) and two concrete types (SCC and CVC). After 28 days of moist curing, the beams and prisms were exposed to accelerated corrosion process using direct current supply. Different tests were performed to detect the corrosion deterioration in the RC specimens including crack pattern and width, ultrasonic pulse velocity (UPV), half-cell potential (HCP), and structural performance (flexural test for beams and pullout test for prisms).The innovative study showed that the SCC specimens (beams and prisms) exhibited higher performance in controlling the corrosion in comparison with CVC beams and prisms. The non-destructive tests (UPV and HCP) showed significant difference between the corroded SCC and CVC specimens. The damage index of the UPV of the corroded CVC beams showed higher values than that of the corroded SCC beams. The HCP values of the corroded CVC beams showed lower negativity than those of the corroded SCC beams. Flexural tests of corroded SCC beams showed higher performance than those of corroded CVC beams. Pullout behavior of corroded SCC prisms showed higher performance compared to corroded CVC prisms. As expected, the CVC and SCC specimens at w/c of 0.35 showed improved corrosion performance compared to the CVC and SCC specimens at w/c of 0.45.

Electrical Resistivity and Half-Cell Potential Studies to assess organic and inorganic corrosion inhibitors’ effectiveness in concrete

Very limited guidelines are available on the use of corrosion resistant inhibitors as a constituent material in concrete due to availability of statistics on its corrosion inhibiting efficiency. So the study is conducted on the M25 grade concrete mixed with few selected corrosion inhibitors of organic and non-organic nature to comprehend the impact of these corrosion inhibitors on the conductivity of electricity in these concretes. Based on the other researchers’ work, four well know corrosion inhibitors such as Calcium nitrate, Di-ethanolamine, Sodium nitrite and Hexamine and are chosen for study. Dosages of 1%, 2%, 3%, 4% and 5% the weight of cement are chosen. Measured electrical resistivity and half-cell potential values of all corrosion inhibitors admixed M25 grade concrete mixes indicates the superior corrosion inhibition ability of calcium nitrate and Di-ethanolamine’s with shows high electrical resistance.

Effect of Organic and Inorganic Corrosion Inhibitors on Strength Properties of Concrete

In the current study, the M25 grade concrete mixes are admixed with various locally available organic and non-organic corrosion inhibitors such as Calcium Nitrite, Sodium Nitrite, Hexamine and Di-ethanolamine to understand the influence of these organic and non-organic corrosion inhibitors on the strength and corrosion resistance properties of concrete. The percentage dosage of admixed inhibitors vary from 1 to 5% by the weight of cement. For M25 grade concrete the optimum percentages of corrosion inhibitor admixture was found to be 4% for Calcium Nitrite, 3% for Sodium Nitrite, 2% for Hexamine and 3% for Di-ethanolamine. Calcium Nitrite corrosion inhibitor admixture imparts increased compressive, split- tensile and flexural strength than other corrosion inhibitors at 28 days. All the corrosion inhibitors used in the study have enhanced the compressive strength, split tensile strength, and flexural strength of concrete. The initial gain of early strength decreased due to anodic process of inhibitors. Measured electrical resistivity and half-cell potential values of all corrosion inhibitors admixed M25 grade concrete mixes directs that calcium nitrate and Di-ethanolamine have shown high electrical resistance indicating their superior corrosion inhibition ability than sodium nitrite and hexamine. Accelerated corrosion test on reinforced concrete beams admixed with corrosion inhibitors confirmed that possible inception of corrosion in calcium nitrate admixed reinforced concrete beams is very low when compared to other corrosion inhibitors used for the study.

The role of Arabidopsis glutathione transferase F9 gene under oxidative stress in seedlings.

Arabidopsis thaliana contains 54 soluble glutathione transferases (GSTs, EC 2.5.1.18), which are thought to play major roles in oxidative stress responses, but little is known about the function of individual isoenzymes. The role of AtGST phi 9 (GSTF9) in the salt- and salicylic acid response was investigated using 2-week-old Atgstf9 and wild type (Wt) plants. Atgstf9 mutants accumulated more ascorbic acid (AsA) and glutathione (GSH) and had decreased glutathione peroxidase (GPOX) activity under control conditions. Treatment of 2-week-old seedlings with 10⁻⁷ M salicylic acid (SA) for 48 h resulted in elevated H₂O₂level and enhanced GST activity in Atgstf9 plants, 10⁻⁵ M SA treatment enhanced the malondialdehyde and dehydroascorbate contents compared to Wt. 50 and 150 mM NaCl increased the GST activity, AsA and GSH accumulation in Atgstf9 seedlings more pronounced than in Wt plants. We found that the Atgstf9 mutants had altered redox homeostasis under control and stress conditions, in which elevated AsA and GSH levels and modified GST and GPOX activities may play significant role. The half-cell potential values calculated from the concentration of GSH and GSSG indicate that this GST isoenzyme has an important role in the salt stress response.

Reusing copper tailings in concrete: corrosion performance and socioeconomic implications for the Lefke-Xeros area of Cyprus

Copper mining and processing activities at an abandoned mine in the Lefke-Xeros area of Cyprus have created a huge environmental contamination problem in the locality. As an alternative mitigation and management measure, we reported in previous studies that these tailings could be used as a concrete making material. In this paper, results of an experimental investigation of the reinforcement corrosion performance and cost efficiency of 0.57 and 0.50 w/b ratio concrete containing copper tailings either as a cement replacement or an additive material are presented. The time to initiation of corrosion and half-cell potential (HCP) of reinforcements were measured. Actual corrosion status of extracted reinforcement bars was also verified by visual inspection. Results showed that while early corrosion initiation occurred in some samples containing tailings as a cement replacement material, delayed corrosion initiation was observed in all samples containing copper tailings as an additive. Although HCP values became slightly more electronegative as tailings content of samples increased, no substantial reinforcement corrosion was observed. Based on corrosion performance and cost efficiency analyses, utilization of 5% pre-wetted tailings either as a cement replacement or an additive material is the best tailings reuse approach. Increased tourism-related businesses associated with reduced pollution of the Lefke-Xeros coastal area would have a positive impact on the socioeconomic status of the community.

염화칼슘이 함유된 제설제로 인한 콘크리트 바닥판 단부의 염해에 관한 사례 연구

Abstract : In this study, the reinforced concrete rahmen bridge damaged by the chloride attack was investigated. According to the investigation, the degraded concretes on cantilever kerb and end part were intensively observed. Thus, the chloride content test and half-cell method were performed to evaluate the degraded parts. As a result, the contents of chloride on degraded parts were C and D grade. On the other hand, the half-cell potential values of rebar in degraded concrete were measured with the minor corrosion. This rebar corrosion is expected to progressing. Chloride content D grade is due to expansion pressure by corrosion of rebar and freeze-thaw by permeate water, could see progresses rapidly degradation. In order to prevent chloride attack to concrete deck caused by deicing salts, corresponding to the chloride critical concentration must maintain grade b or at least grade c. Chloride condition evaluation standard apply to evaluation of marine structure chloride attack with chloride attack by deicing salts.

Experimental investigation of time dependent non-linear 3D relationship between critical carbonation depth and corrosion of steel in carbonated concrete

This paper aims at the experimental investigation of time dependent non-linear relationship between critical carbonation depth and corrosion rate of steel in carbonated concrete by laboratory controlled experimentation under severe environmental condition. In this research, three-dimensional experimental observations are taken consecutively involving carbonation depth, half-cell potential and elapsed time as well as the gravimetric corrosion mass loss. The experimental observations revealed an interesting non-linear relationship between the above said measurements due to the varying resistivity of carbonated concrete. It is also found that the carbonation induced corrosion does not start until the carbonation depth reaches a certain critical level from the steel rebar and the half-cell potential values become constant after carbonation reaches the critical depth and then start rising again after carbonation reaches the rebar level.

Underwater half-cell corrosion potential bench mark measurements of corroding steel in concrete influenced by a variety of material science and environmental engineering variables

This paper aims at detailed investigation of the chloride induced corrosion potential in submerged reinforced concrete structures in comparison to various other relative humidity conditions. Corrosion cells with different concrete material compositions under four different environmental engineering conditions (air dry, submerged, 95% RH and alternate wetting–drying) were used to explore the underwater half-cell corrosion potential in a comparative study with reference to other environmental conditions by taking into account the actual field engineering material variables such as concrete cover depth, relative humidity, water–cement ratio and chloride content. From the experiment results it was verified that the half-cell potential values for reinforced concrete specimens submerged underwater are not the true representative of corrosion rate and need to be re-calibrated in the light of experiment results obtained in this research. For this purpose, detailed bench mark testing has been conducted in this paper involving a variety of material and environmental variables. This will provide basis for the future calibration of underwater half-cell potential values of corroding steel in chloride contaminated concrete in a variety of material and environmental variables for which the previous research data is limited.

Corrosion resistance of self-consolidating concrete in full-scale reinforced beams

Abstract The corrosion of steel reinforcement embedded in full-scale self-consolidating concrete (SCC) beams was investigated compared to normal concrete (NC). 400 mm width × 363 mm depth × 2340 mm length beams containing epoxy- and non-epoxy-coated stirrups were monitored under an accelerated corrosion test. The corrosion performance of NC/SCC beams was evaluated based on the results of current measurement, half-cell potential tests, chloride ion content, mass loss and bar diameter degradation. The investigation also included the effect of admixture type and the size of specimen on corrosion performance. In general, SCC beams showed superior performance compared to their NC counterparts in terms of corrosion cracking, corrosion development rate, half-cell potential values, rebar mass loss and rebar diameter reduction. However, SCC beams showed localized corrosion with concrete spalling due to non-uniform concrete properties along the length, which was a result of the casting technique. The results also showed that the difference between SCC and NC mixes in terms of corrosion was more pronounced in large-scale beams, and that types of admixture used in SCC have no influence on corrosion performance.

Cathodic protection of concrete structures containing calcareous aggregates in tropical‐humid marine environments

PurposeTo evaluate the performance of two cathodic protection (CP) systems applied to steel reinforced concrete structures manufactured with calcareous aggregates and exposed to the tropical‐humid marine environment at the Yucatán peninsula in Mexico.Design/methodology/approachRectangular concrete beams were manufactured using a water/cement ratio = 0.65, with and without the addition of NaCl in the mixing water. Specimens subjected to CP, eight to impressed current cathodic protection (ICCP) and eight to sacrificial anode cathodic protection (SACP) were partially immersed in natural seawater during 360 days. The half cell potential (HCP) and the current consumption were recorded during the total exposure time.FindingsThe measured HCP values of the steel rebar in the beams subjected to SACP did not attain protection potential levels. However, the galvanic couple Zn‐steel provided enough current for the protection of the steel. Visual inspection of concrete cores extracted from the beams indicated that corrosion products were not present at the steel‐concrete boundary. On the other hand, the ICCP applied to eight concrete beams provided excellent corrosion protection to the steel rebar.Originality/valueThis work revealed that the SACP system (thermally sprayed zinc) works well in high relative humidity environments and can be successfully used to protect steel reinforced concrete structures manufactured with calcareous aggregates which are endemic of the region and commonly used for infrastructure construction in the Yucatán peninsula.

Critical polarization resistance in service life determination

The service life of concrete exposed to chloride environments was measured experimentally, and polarization resistance and half-cell potential values were used to monitor corrosion. Service life was considered as the combination of the initiation phase and a part of the propagation phase in which the degree of corrosion is lower than an “tolerable” degree of corrosion. Polarization resistance corresponding to this tolerable degree of corrosion was termed the “critical polarization resistance,” or CPR. Subsequently, CPR was used to establish the service life of four grades of concretes prepared from four cements; the influence of the type of cement was also studied. Polarization resistance was found to be a much more useful and reliable technique in service life evaluation than the half-cell potential.

Corrosion Surveys of Prestressed Bridge Members Using a Half-Cell Potential Technique

Abstract Potential surveys were conducted on prestressed bridge girders using a copper-copper sulfate (Cu-CuSO4) half-cell. The study demonstrated good correlation between half-cell potential values and results of other tests, particularly visual examination, provided there was electrical continuity between the standard and in-situ half-cells. Especially reliable data regarding the state of corrosion of prestressing steel were obtained in pretensioned girders reinforced with seven wire strands and in post-tensioned girders reinforced with bonded tendons with a steel sheath. Results obtained from examination of girders reinforced with post-tensioned unbended tendons were not conclusive.