Probability Of Corrosion Research Articles

Mitigation of Steel Corrosion Threshold Utilizing Plant-Based Green Corrosion Inhibitors through Electrochemical Techniques

Corrosion of steel reinforcement is a major cause of deterioration in reinforced concrete structures. The corrosion process is influenced by the concrete-steel interface, with the alkaline concrete pore solution initially providing passivation. However, ingress of aggressive substances like chlorides can disrupt the passive layer, initiating active pitting corrosion above a threshold level often taken as 0.4% chloride by cement weight. Once the chloride threshold is exceeded, corrosion propagation depends on oxygen and moisture availability. The resulting rust formation causes expansive cracking and spalling of the concrete cover. Corrosion damage can be mitigated through use of inhibitors like calcium nitrite though high dosages impair concrete strength. Recently, plant-based organic compounds have shown promise as green corrosion inhibitors. The corrosion behavior of steel in concrete can be evaluated through impressed accelerated corrosion testing along with electrochemical techniques like half-cell potential mapping and resistivity measurements. These allow assessment of the probability of corrosion and corrosion rate. Techniques like linear polarization resistance and electrochemical impedance spectroscopy can also quantify instantaneous corrosion rate. Proper structural condition assessment and repair using both conventional and green inhibitors is crucial to control steel corrosion, maintain service life and ensure safety. Further research is needed on green corrosion mitigation methods and advanced non-destructive testing techniques.

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

A study of chloride binding capacity of concrete containing supplementary cementitious materials

Chloride-induced steel corrosion is known to be a very common kind of deterioration of reinforced concrete. It is beneficial to bind free chloride ions to reduce the corrosion probability of the reinforcement embedded in the concrete. The binding capacity of the concrete varies according to its cementitious system. This paper investigates the chloride binding capacity of different kinds of supplementary cementitious materials (SCMs): Ground granulated blast furnace slag (GGBFS), Fly ash, and Metakaolin as a partial replacement of Ordinary Portland Cement (OPC). Different properties of concrete after chloride binding are assessed by carrying out the following tests: half-cell potential, accelerated corrosion test, compressive strength, rapid chloride penetration test, sorptivity test, measuring pH value of concrete, and XRD. The results showed that utilizing the SCMs in concrete can enhance the chloride binding capacity, especially those materials that have high quantities of aluminate and calcium in their chemical composition like GGBFS. Based on testing results, it’s recommended that the limit of the chloride content in the different codes should be revised regarding the binding capacity according to the type and quantity of the cementitious materials used.

A dynamic risk assessment model based on multidimensional and quantitative inference theory

With the continuous increase in petroleum consumption and the trend towards more refined management, crude oil storage tanks are playing an increasingly crucial role in the petrochemical industry. However, the corrosion issue of crude oil storage tanks has consistently been a major factor limiting their service life, and leaks in crude oil tanks are often attributed to corrosion of the tank bottom. Due to the high cost and complexity associated with tank opening inspections, in this paper, directly observable information and physical quantities are utilized as indirect evidence, combined with Bayesian network, to indirectly determine the probability of tank corrosion. This approach allows for selective internal tank inspections, enabling effective risk assessment while also facilitating cost savings. Some parameters in the Bayesian network model are obtained through a probability estimation model combining expert experience and fuzzy set theory. Finally, the feasibility of the method is demonstrated by citing examples. The current model can offer a relatively reliable reference for evaluating the risks associated with tanks and their ancillary facilities, while also reducing the costs of tank inspections to some extent.

IoT for Cathodic Protection System as Iron Concrete’s Corrosion Protection

Iron concrete or reinforcement steel is steel used for reinforcement of concrete construction or known as reinforced concrete. Iron concrete can undergo a corrosion process caused by chemical or electrochemical reactions between reinforcement steel and its environment. One way to protect concrete from corrosion is cathodic protection. There are two types of cathodic protection, namely sacrificial anodes and impressed current cathodic protection (ICCP). ICCP is more commonly used for protection in reinforced concrete structures. In ICCP, negative current flows to the iron concrete and positive current flows to the anode. This is to protect the concrete from corrosion. In addition to the corrosion protection system, there is also a half-cell potential test to measure the chance of corrosion of the concrete. The project used IoT to monitor and control the ICCP. Measurements are made by reading the potential difference between the reference electrode and the iron concrete. The probability of corrosion can be determined by reading the corrosion probability table with ASTM C879-09 standard. The ICCP system in general still uses the manual method so that there are time efficiency problems in controlling the voltage and current for ICCP purposes, cannot schedule the provision of electric current and monitor it at any time, especially if the electric current flowing in the concrete is higher than the standard it should be. Based on the results of the tests carried out, the IoT system can regulate the power supply by setting the voltage and current and can schedule the power supply to provide electric current to the iron concrete and can provide notifications if the electric current flowing in the concrete is more than or less than ICCP standard.

Analyzing chloride diffusion for durability predictions of concrete using contemporary machine learning strategies

Analyzing the migration of chloride ions in concrete can enhance its durability and decrease the probability of corrosion. Furthermore, machine learning (ML) offers a promising, cost-effective, and less intricate alternative to traditional experimental methods for accurately forecasting cementitious composites' chloride migration coefficient (Dnssm). This study utilized advanced ML methods like support vector machine (SVM), artificial neural network (ANN), and k-nearest neighbor (KNN) to forecast the Dnssm of concrete accurately. A comprehensive database was established considering significant input features that can impact Dnssm. The models undergo verification with unseen data, utilizing various statistical performance measures. The verification findings validate that all three models (SVM, KNN, ANN) accurately predicted the Dnssm with high precision. However, the SVM model outperformed with a higher coefficient of determination (R2) score of 0.90, whereas ANN and KNN yielded R2 scores of 0.88 and 0.83, respectively. The model has the capacity to substitute laborious, resource-intensive and time-consuming lab testing. Moreover, the RReliefF analysis indicated that water/binder and cement type are the prominent input factors affecting the target variable Dnssm.

The Italian Guidelines for special inspections of post-tensioned concrete bridges: review and case study

Post-tensioned (PT) concrete bridges are structural systems characterized by intrinsic fragility. The assessment of their health condition is very difficult due to their nature, which prevents the detection of degradation in PT elements through conventional investigation methods and/or visual inspections. For this reason, the Italian Guidelines for the maintenance of existing bridges envisage special inspections to assess the condition of the post-tensioning system. According to the dedicated Guideline, the special inspection procedure consists of four steps. First there is Step O, which identifies the number and location of PT samples to be investigated based on the historical•critical review of available documentation and the visible defects in the post-tensioned members. Then, in Step 1 a preliminary analysis of the identified PT elements is performed, identifying the presence and location of active defects and grout voids, as well as the probability of corrosion of the reinforcement through non-destructive tests. In Step 2, the analysis of defects becomes more accurate, determining the probability of corrosion and estimating the level of stress in the concrete and in post-tensioned cables through locally destructive tests. Step 3 is applied if the outcome of Step 2 is uncertain and involves the experimental analysis of the overall structural response of the bridge. Eventually, in case the presence of damaged PT elements is confirmed, a load assessment of the structure is performed. The objective of this study is to evaluate the effectiveness of the investigation method proposed by the Italian Guidelines, highlighting its strengths and potential weaknesses. The procedure is applied to the Dora Riparia River Bridge, located in Avigliana (Turin) on provincial road SP197. The bridge consists of seven spans, 21.4 m long, and is characterized by a simply supported static layout; each span has four post-tensioned I-shape beams and four post-tensioned diaphragms.

Understanding and Modeling the Stochastic Nature of Corrosion Reactions in Atmospheric Conditions

Corrosion is a detrimental materials degradation mechanism to many in-service alloys and alloy systems. The stochastic nature of corrosion processes makes prediction and identification of degradation a monumental task. Additionally, the wide range of materials utilized in complex systems, coupled with variable environments, further complicates this process. Here, we utilize Finite Element Method (FEM) models coupled with statistical software (Dakota), and machine learning techniques to build a generalized framework to evaluate the probability of corrosion occurring. The ability to input defined, statistically distributed model parameters allows for the identification of corrosion probability and provides for the discovery of important parameters for future experimental efforts. In addition to the statistical predictions of corrosion, machine learning (ML) techniques allow for accelerated predictions from models, potentially reducing both time and computation effort for corrosion predictions (i.e., rate and extent of corrosion). The framework for corrosion modeling will be discussed and applied to various models, including reactive transport models. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. This document is SAND2023-02444C.

Modeling of chloride-induced corrosion in concrete bridge using the simplified and full probabilistic methods

Concrete and reinforced concrete structures are subjected to chloride corrosion, which can shorten their service life and safety of use. Reliability and safety prediction of concrete structures is a crucial task for optimizing their life cycle design and maintenance and for minimizing their life cycle costs. In the paper a probabilistic analysis of concrete durability in structural members is presented. Two methods: simplified-probabilistic and full-probabilistic have been applied for modelling chloride-induced corrosion in concrete structures. The uncertainty of the key parameters including surface chloride concentration, chloride threshold, cover depth and diffusion coefficient, which govern the chloride ingress into concrete and corrosion of reinforcing steel have been analyzed. A case study of a reinforced concrete bridge has been used to illustrate the capability and efficiency of these probabilistic methods in modeling the uncertainty and predicting the time-dependent probability of corrosion. FREeT-D and ProCAAT software have been used for the analysis.

Durability design and construction enhancing of concrete structures in mesoscopic approach: A case study of a large-scale anchorage structure

The durability challenges in concrete infrastructure are complex, with difficulties in considering the multiscale material variation and multiphysics deterioration mechanism during long-term service. This study aims to investigate the structural durability from material scale and predict the probabilistic evolution of structural performance by numerical approach. This paper considers the influence of concrete mesostructure by mesoscopic modeling. For the actual large-scale concrete structure, the different durability problems and different environmental exposures are investigated comprehensively in numerical approaches. Based on the evaluation of reliability indices on structural durability, suggestions are proposed for the structural design and detailed protective measures. With the simulation with 0.1 mm element size and 3-hour time step, the durability deteriorations on the anchorage structure of the Shiziyang Link Project are analyzed, revealing chloride ingress depths, carbonation depths, and the occurrence of corrosion. For the atmospheric zone with a 50 mm concrete cover, carbonation is the governing factor leading the reinforcement corrosion, and the extreme frontal depth can reach 59.4 mm. For the splashing and tidal zone, the carbonation with an extreme depth of 53.0 mm is the major concern for durability, but the 70 mm concrete cover is thicker to protect the structure from local corrosion. For the immersed zone over 10 m underwater, the chloride ingress depth can reach 70 mm thickness of concrete cover after short service. By comparing the depth distributions with the thickness of the concrete cover, the failure probabilities of reinforcement corrosion of three zones can reach 65.5%, 0.0%, and 100%, respectively, after the 100-year service. To meet the restricted durability limit state requirement with under 1% of target corrosion probability, the service lives of three zones range from 6.1 years to over 100 years. The improvement solutions are presented and evaluated for anchorage structural durability. The change of aggregates from rounder shapes to slender shapes can reduce the deterioration depth by about 2.4%, and the probability of reinforcement corrosion under concrete cover can be reduced a lot. For the concrete joint, the recommended seal takes advantage of these basic types, and its resistance to the local carbonation in the joint is also verified by comparison.

Influence of stone dust content on carbonation performance of manufactured sand concrete (MSC)

This study investigates the influence of stone dust content on the carbonation performance of manufactured sand concrete (MSC) to improve its durability and promote the application of manufactured sand. The carbonation depth, pH of the pore solution, and half-cell potential of the rebar were tested using MSC with different stone dust contents. The mechanism of MSC carbonation was also analysed using scanning electron microscopy (SEM). The test results showed that the carbonation depth and corrosion probability of the rebar first decreased and then increased with an increase in stone dust content. The carbonation depth and pH of the pore solution of MSC can be divided into complete carbonation, partial carbonation, and non-carbonation zones. When the stone dust content was 7% and at different carbonation ages, the carbonation depth reached its minimum value, the half-cell potential of the rebar reached its maximum value, and the end depth and length of the partial carbonation zone reached their minimum values. Meanwhile, the rebar half-cell potential was only in the medium-probability corrosion zone when the carbonation age was 120 d and the stone dust content exceeded 7%, whereas the remaining cases remained in the low-probability corrosion zone. SEM showed that a low stone dust content increased the density of concrete through physical filling and chemical reactions. However, high stone dust content reduced the working performance of concrete and increased its porosity after forming. In conclusion, the optimum stone dust content was 7% when comprehensively evaluating the carbonation properties of the MSC.

Influence of migrating inhibitor concentration on corrosion resistance of steel reinforcement in concrete

To increase the service life and durability of reinforced concrete structures, new technologies have been developed, such as cathodic protection, re-alkalinization, chloride extraction, and the use of corrosion inhibitors. This study evaluated the influence of cement type, concrete cover thickness, and the addition of organic migrating corrosion inhibitor (MCI) on the corrosion resistance of the embedded steel in concrete against the induced action of chloride ions. To accomplish this, corrosion tests were carried out using electrode potential techniques simultaneously with acceleration cycles of chloride attack. Four mixtures with two levels of reinforcement cover (25 and 40 mm) were subjected to 30 weekly cycles of chemical attack: a reference mixture (without inhibitor) and three others adopting concentration levels of 0.30%, 0.45%, and 0.60% of MCI in the volume of concrete. The concrete properties (compressive strength, voids, specific gravity, and water absorption by immersion and capillarity) were verified. In the corrosion tests on reinforced concrete with lower cover thickness, the mixture with 0.60% MCI addition showed the best results: corrosion potential values less negative than -200 mV, with less than 10% probability of corrosion.

Assessment of AC Corrosion Probability in Buried Pipelines with a FEM-Assisted Stochastic Approach

In this paper, a stochastic approach is combined with field theory and circuit methods to study how the geometrical and electrical properties of holidays (defects or pores in the insulating coating) in a metallic pipeline influence the probability of exceeding the current density limit for corrosion. Three-dimensional FEM simulations are conducted to assess the influence of the shape and electrical resistivity of the pore on the computed spread resistance value. The obtained results are then used to evaluate the probability of exceeding a given current density value for different sizes of pore and soil resistivities. Finally, a case of 50 Hz interference along a pipeline-transmission line routing is examined. The probabilistic approach presented in this paper allows the pipeline sections more subjected to the induced AC corrosion risk to be identified to be used as an auxiliary tool for adopting preventive protection countermeasures. Lastly, unlike most papers devoted to assessing electromagnetic interference on pipelines, the present work uses a probabilistic rather than a deterministic approach, representing its main novelty aspect.

Long-term reinforcement corrosion in low carbon concrete with a high volume of SCMs exposed to NaCl solutions and field marine environment

Chloride-induced corrosion in low carbon concrete with a high volume of SCMs exposed to (i) accelerated corrosion by impressed current, (ii) 9-year NaCl-simulated tidal condition and (iii) 5-year field marine tidal condition was compared in this study. The effectiveness of different exposure conditions and indicators in distinguishing the parameters affecting the corrosion resistance of concrete was investigated. The results showed that at a high w/b ratio of 0.6, the accelerated corrosion test provided inconsistent ranking for the corrosion resistance of binders when continuous and intermittent impressed voltage were applied. At a w/b ratio of 0.4, the electrochemical measurements from both accelerated corrosion and laboratory-simulated tidal exposure confirmed the advantage of 30 % FA blended cement concrete in protecting reinforcement, whereas results from two exposure conditions denoted opposite ranking for the corrosion resistance of GP cement and 50 % slag blended cement concrete. The statistical analysis of the 674 independent data points (Ecorr, Rp) suggested that using −465 mVSCE as the upper limit for indicating a higher than 90 % corrosion probability was more reliable than the −350 mVSCE from ASTM C876. Compared to field marine tidal exposure, long-term wet/dry cycles in 3 % NaCl induced faster corrosion initiation and propagation, thereby higher weight loss of reinforcement. The chloride contents permitting corrosion initiation were higher for concrete with more binder due to a higher alkalinity. The complex interaction between chloride, alkalis and reinforcement corrosion leads to difficulty in discriminating the corrosion resistance of various binders, especially in long-term exposure.

Experimental Investigation on Carbonation due to Climate Change Impacts

<p>Various investigations have been carried out to evaluate the infrastructure’s augmented vulnerability owing to concrete carbonation persuaded by the changes in the environment during recent years. Due to global warming and its effect, carbon dioxide emission levels in the atmosphere get increased and this would further increase the probability of carbonation-induced corrosion in concrete structures. In this present study, an empirical model is used to identify the diffusion coefficient of carbon dioxide (CO2) in concrete. Water cement (w/c) ratio of 0.45, 0.5, and 0.55 has been considered with emission scenarios of Representative Concentration Pathway (RCP) 8.5 and 4.5 respectively. The research findings through empirical modeling proved that the depth of carbonation has a direct relationship with water cement ratio and it is also predicted that by the year 2100, considering 2000 as the base year, the carbonation depth may raise up to 78% for reinforced concrete structures subject to various climatic conditions such as temperature, humidity, etc.</p>

First-principles study on the corrosion-resistant of lead-bismuth to rough stainless steel surface

The corrosion of lead-bismuth on steel has received much attention in ADSs. Unfortunately, the current studies are mostly based on the ideal Fe surface, but in reality, the surface of the steel is rough. In this work, the rough surface is built. By performing first-principles calculations, using adsorption and escape energies to evaluate the mechanism of dissolution corrosion on rough surfaces. The smaller adsorption energy indicates more stable adsorption properties on the rough surface for adatoms. According to the process of dissolution corrosion, the surface is more likely to be corroded. The energetics results mean that bismuth atoms are more stable on the rough surface. Combined with escape energy, rough surfaces are more susceptible to corrosion than ideal surfaces. This is further demonstrated by calculating the charge density difference of surface. Based on previous research, three alloying elements, Al, Si, and Mo, which have the best corrosion resistance, were selected for further discussion. Finally, adsorption energy is utilized to evaluate how alloy atoms affect surface dissolution corrosion. The results show that when there are four alloy atoms on the surface, the probability of Pb or Bi atom corrosion on the surface is the least.

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.

Non-uniform Corrosion Mechanism and residual life forecast of marine engineering concrete reinforcement

Reinforced concrete structures are commonly employed in civil engineering due to their low cost and high performance. However, their exposure to the marine environment, which is typically characterized by elevated salt content and humidity levels, heightens the probability of corrosion. Such corrosion can lead to a decrease in the service life of these structures, which is of utmost importance to predict in order to prevent potential safety hazards. To address this issue, this study investigated the corrosion mechanism of reinforced concrete structures in the marine environment and found Cl- concentration to be the most critical parameter for the corrosion of steel. Afterward, a predictive model is proposed based on the Back Propagation Artificial Neural Network (BPANN) to estimate the residual service life of reinforced concrete structures in different marine environments by forecasting the Cl- concentration in reinforced concrete components. The results demonstrate the high accuracy of the proposed BPANN model, with a maximum relative error of 6.292 %. Consequently, the residual service life forecast system of reinforced concrete structures proposed in this study can provide useful guidance based on the simplistic framework for designing concrete structures in the marine environment by predicting their effective service life. Thus, this study provides valuable insights for promoting the safety and economic benefits of reinforced concrete structures in the marine environment.

Investigating the corrosion resistance of Cu-doped Ni-Mo low alloy steel through electrochemical tests

Corrosion resistance of Cu-doped Ni-Mo low alloy steel (Ni-Mo steel) in marine environments was systematically investigated through microstructure observation and galvanostatic polarization tests. Results show that solid solution Cu improved the corrosion thermodynamic stability of steel. The increasing Cu content promoted the formation of Cu-rich precipitates, martensite-austenite island, granular bainitic and high angle grain boundary, increasing the surface potential difference and the occurrence probability of local galvanic corrosion on steel surface. The addition of Cu improved the protectiveness of corrosion product film after galvanostatic polarization tests relying on the functions of CuFeO2 and CuO, whose formation was mainly related to the solid solution Cu in Ni-Mo steel.

Repair mortars with water treatment plant sludge (WTPS) and sugarcane bagasse ash sand (SBAS) for more eco-efficient and durable constructions

Water treatment plant sludge (WTPS) and sugarcane bagasse ash sand (SBAS) can be used as fine aggregate in cementitious composites. This paper aims to evaluate carbonation depth, chloride penetration, steel corrosion probability, and corrosion rate of cementitious repair mortars produced with 3% WTPS and 30% SBAS. The results showed SBAS mortars have the best performance in relation to carbonation and chloride penetration tests. WTPS mortars have similar results to the reference sample. Both mixes with by-products were able to provide a more protective environment for steel reinforcement. They presented a delayed steel corrosion probability of 25% (for 3WTPS) and 113% (for 30SBAS) in comparison to the reference sample. This is due to increased alkalinity and refinement of pores given by incorporation of fine waste materials. Moreover, 3WTPS and 30SBAS can significantly reduce corrosion rates of steel reinforcement in the order of 70% and 97%, respectively. Therefore, 3WTPS and 30SBAS composites can be satisfactory used in jacketing repair mortars for more eco-efficient and durable constructions.