Steel Corrosion In Concrete Structures Research Articles

Transfer learning enables prediction of steel corrosion in concrete under natural environments

Existing machine learning (ML) models for corrosion rate prediction of steel in cementitious materials are typically established based on laboratory datasets obtained under controlled material and environmental conditions, which questions their applicability to more realistic and complex scenarios. Transfer learning (TL), as a branch of ML, can extract knowledge from a source domain, which can be utilized to improve prediction accuracy on a target domain. In this work, a TL paradigm, grounded on an advanced ML model built for steel corrosion in mortars, is proposed to elevate the efficacy of existing ML models in forecasting corrosion rate of steel in concrete under natural environments. The results underscore the prominence of certain features, specifically electrical resistivity, chloride-to-hydroxide concentration ratio ([Cl−]/[OH−]), cement proportion, corrosion potential, porosity, and water content. In addition, the interplay of diverse quantities of features and feature amalgamations exercises a substantial influence on the performance of ML models. It is found that TL strategy enhances the ML model's predictability for corrosion rate in concrete under natural environments. The knowledge pertaining to steel corrosion under controlled laboratory conditions can be transferred to enhance the model's ability to predict steel corrosion in concrete under natural conditions. These results underscore TL's potential in enabling reliable corrosion rate predictions in existing in-service concrete structures, especially with limited data and deficient information for steel corrosion in concrete structures.

A Review on Study of Rehabilitation and Repair Techniques of R.C.C. Building

Abstract: Cement concrete reinforced with steel bars is an extremely popular construction material. One major flaw, namely its susceptibility to environmental attack, can severely reduce the strength and life of these structures. External reinforcement using steel plates have been used in earlier attempts to rehabilitate these structures. The most important problem that limited their wider application is corrosion. This project emphasize on Rehabilitation of R.C.C. structures. The purpose of this project is to highlight the various techniques of repair and rehabilitation methods to be undertaken for structures with defects and deficiencies that necessitate rehabilitation. Repair and Rehabilitation methods currently used are reviewed on the basis of present knowledge and the merits of a holistic system approach. This project focuses on visible symptoms of the problem rather than on invisible problems as well as the possible causes behind them. This project focuses on various techniques and repair materials used for the satisfactory performance of the repaired structure. This project presents an analysis of concrete illnesses, and problems leading to unsatisfactory performance of repaired concrete structure. This project describes the analysis the types of surface preparations that are commonly adopted in Indian conditions. This project highlights the problem of reinforcing steel corrosion in concrete structures and attempts to provide the remedial measures available in design to mitigate the effects of corrosion. In view of these limitations the various types of coatings are available and the precautions to be taken in the selection of coatings systems are also discussed. This also highlights the importance of epoxy resins and various methods of epoxy in the construction applications such as repairing of cracks, patching, grouting of concrete, structural adhesives and anti-corrosive linings etc. The conclusive part deals with cost comparison between present approximate estimated cost of new building & rehabilited building.

Iron-oxide-identifying imaging method based on a wide-energy neutron beam for corrosion inspection in reinforced concrete structures.

To prevent potential hazards caused by steel corrosion, there is an increase in demand for non-destructive inspection or monitoring of reinforcing steel corrosion in concrete structures. In this study, an iron-oxide-identifying imaging method is proposed that is based on a neutron resonance transmission imaging technique. According to the correlation analysis of the resonance characteristics of iron and oxygen and the elemental fractions, the iron oxides in the corroded reinforced concrete samples were accurately identified and mapped. The volume identification limit of the rust layer was further analyzed, and it is close to 0.1mm. For the resonance energies of nuclides Fe-56 and O-16 in the tens and hundreds of keV range, the intensity of neutrons at the corresponding energy is only lower about three orders of magnitude after passing through a 40-cm-thick concrete block. The iron-oxide-identifying imaging method could also obtain a clear image of the iron-oxide distribution inside the 20-cm-thick corroded reinforced concrete sample.

Relationship model between surface strain of concrete and expansion force of reinforcement rust

Concrete cracking caused by corrosion of reinforcement could significantly shorten the durability of reinforced concrete structure. It remains critical to investigate the process and mechanism of the corrosion occurring to concrete reinforcement and establish the theoretical prediction model of concrete expansion force for the whole process of corrosion cracking of reinforcement. Under the premise of uniform corrosion of reinforcing steel bars, the elastic mechanics analysis method is adopted to analyze the entire process starting from the corrosion of steel bars to the cracking of concrete due to corrosion. A relationship model between the expansion force of corrosion of steel bars and the surface strain of concrete is established. On the cuboid reinforced concrete specimens with square cross-sections, accelerated corrosion tests are carried out to calibrate and verify the established model. The model can be able to estimate the real-time expansion force of reinforced concrete at any time of the whole process from the initiation of steel corrosion to the end of concrete cracking by measuring the surface strain of concrete. It could be useful for quantitative real-time monitoring of steel corrosion in concrete structures.

Reinforcement bar Corrosion - Causes and Management

Concretes are composite materials which decay as a result of steel corrosion in concrete structures is mostly accelerated in environments laden with chlorides and industrial effluent gases as well as harsh chemicals employed in and those generated from wastes in agricultural industries. This review summarises the effects of various environmental pollutants which promote deterioration of concretes with resultant corrosion of reinforcing bar (rebar). An overview of traditional and current methods for significant reduction of this mode of material deterioration is described. Discussions on management tools for rebar corrosion in agricultural and marine environments have been highlighted. Repair methods include the traditional application of patch repair mortar which has been modified with polymeric materials to improve adhesion and reduce porosity. The use of cathodic protection system to reduce rebar corrosion to its barest minimum has gained currency. Attention should be directed at corrosion reduction practices at the design and planning stages as well as modification concrete mixes with modified agricultural wastes/products and polymers.

Monitoring Steel Bar Corrosion in 3.5 Wt.% NaCl Solution Using a Fiber Optic Corrosion Sensor

Reinforcement steel in concrete structures is initially protected by a passive film formed due to the alkaline concrete pore solution, which contains hydroxyl ions released from cement hydration. This protective film may be destroyed due to neutralization of the concrete pore solution or penetration of aggressive chemicals such as chloride from de-icing salt or marine environments. Breakdown of passive film causes initiation of corrosion that is followed by corrosion propagation, and over time results in cracking of concrete cover, reduction of mechanical properties of steel bar, bond loss between steel and concrete, as well as reduction of carrying capacity of concrete structural members and systems. According to a NACE report released in 2002, the annual direct corrosion cost for replacement and maintenance of highway bridges in the U.S. was estimated $13.6 billion [1]. The indirect cost due to traffic delay or loss of productivity during the replacement or maintenance period is ten times higher than the direct cost. Moreover, steel corrosion in concrete structures is also a potential threat for human life if structures collapse when the key members are subjected to corrosion attack. A lot of methods or techniques have been proposed or developed to monitor corrosion of reinforcement steel in concrete structures, which can be broadly divided into two categories: electrochemical and non-electrochemical. Electrochemical methods include half-cell potential measurements, electrochemical noise, electrochemical impedance, linear polarization resistance and solid embeddable reference electrodes. Non-electrochemical methods use techniques such as acoustic emission, ultrasonic wave, piezoelectric transducer, ground penetration radar, and optical fiber. Use of optic fiber to monitor steel corrosion in concrete structures have many advantages compared with conventional methods, such as small size, immunity to electromagnetic interference, high precision and sensitivity, capability of multiplexing in large sensor networks. In our previous study, an optical fiber corrosion sensor was proposed based on the sensing principle of long period grating [2], and its mechanism and sensitivity was characterized in 3.5 wt.% NaCl solution [3]. However, the effectiveness of this corrosion sensor to monitor corrosion evolution of reinforcement steel has not been investigated yet. In this study, the corrosion sensor was employed to monitor corrosion behavior of steel bar in 3.5 wt.% NaCl solution, and its correlation with corrosion evolution of steel bar and its effective service life were studied experimentally. This fiber optic corrosion sensor was coated with an inner layer of silver and an outer layer of Fe-C coating. The inner silver was sputtered coated with a thickness of 800 nm, and the outer Fe-C coating was electroplated with a thickness of 20 um. A small piece of steel bar was cut, prepared and tested in 3.5 wt.% NaCl solution, together with the fiber optic corrosion sensor. The corrosion behavior of both the outer Fe-C layer and the steel bar was investigated with electrochemical impedance spectroscopy (EIS), and the change in the light spectrum was recorded with an optical sensing interrogator. EIS results showed that the corrosion behavior of steel bar remained stable throughout the whole test period, while the corrosion resistance of Fe-C layer gradually decreased with time. Due to the limitation of interaction range between the coating layer and the light propagating in the fiber as well as the coating thickness, this fiber optic corrosion sensor can only monitor the corrosion of steel bar for 18 hours in 3.5 wt.% NaCl solution. P.H. Koch, N.G. Brongers, Y.P. Thompson, “Corrosion Costs and Preventive Strategies in the United States”, NACE International Houston, TX, USA, 2002 Publication No. FHWA-RD-01–156.Chen, F. Tang, Y. Bao, Y. Tang, G. Chen, “A Fe-C Coated Long-Period Fiber Grating Sensor for Corrosion-Induced Mass Loss Measurement”, Optics Letters, Vol. 41, pp 2306-2309, 2016.Chen, F. Tang, Y. Tang, M. J. O’Keefe, G. Chen, “Mechanism and Sensitivity of Fe-C Coated Long Period Fiber Grating Sensors for Steel Corrosion Monitoring of RC Structures”, Corrosion Science, Vol. 127, pp 70-81, 2017.

Integrated sensor network for monitoring steel corrosion in concrete structures

<p class="Abstracttext-VITRUVIO">Corrosion is one of the main triggering factors affecting the service life and durability of structures. Several methods are used for corrosion studies but electrochemical techniques are the most commonly applied. Corrosion processes monitoring and control by means of non-destructive techniques, such as the implementation of embedded sensors, has been the target of many works. It is possible to obtain relevant information of structural corrosion processes in real time. This document describes a system including specific equipment and which allows obtaining relevant information about these corrosion processes. This system is formed by a sensor network. There are several types of electrodes, which are distributed throughout the structure under study and a specific equipment developed by the research group, which is used to determine pertinent parameters such as the corrosion potential (E<sub>corr</sub>) and the corrosion density (i<sub>corr</sub>) by applying sequences of potentiostatic pulses. The system allows to reliably determine the corrosion rate in different areas of the structure. The sensor, due to its configuration, provides information of a specific area of the structure, but on the other hand it is involved in the galvanic events that can occur along the structure by differential aeration, galvanic cells, etc. because the sensor is not isolated from the structure. This system also procures information of buried and submerged elements. Besides, it is possible to obtain information related to temperature, concrete resistance. The system includes specific potentiometric sensors to monitor chloride access and carbonatation processes.</p>

Evaluation of damage progression in concrete structures due to reinforcing steel corrosion using acoustic emission monitoring

Acoustic emission (AE) monitoring was employed to detect and identify the extent of degradation resulting from reinforcing steel corrosion in concrete structures. Reinforced concrete samples were subjected to an accelerated corrosion test and corroded until they reached five different levels of mass loss of steel: 1, 2, 3, 4, and 5 %. The corrosion activity of all samples was continuously monitored using attached piezoelectric AE sensors and a multichannel data acquisition system. The results obtained from AE monitoring were analysed and compared to those obtained from half-cell potential (HCP) measurements, the amount of anodic current passing with time, and concrete cover cracking. The study analysed AE signal strength parameters including cumulative signal strength, historic index [H(t)], and severity (Sr) to detect the corrosion initiation, and subsequently, to classify the extent of damage following the corrosion progression. The study also aimed to correlate these parameters to both the degree of mass loss and concrete cover crack width. The results showed that the AE signal strength parameters can be exploited to characterize different degrees of damage from corrosion initiation and up to 5 % steel mass loss. These parameters can be analysed to detect the corrosion initiation earlier than the HCP test. This study also presented damage classification charts that can be used to correlate the level of steel mass loss and/or crack width to the AE signal strength parameters. Given these points, the outcomes of this investigation are substantial for advancing the application of acoustic emission for structural health monitoring in concrete structures.

Non-Destructive Inspection Method and Application Research of Steel Corrosion in Concrete Structures

In the reinforced concrete structure, steel corrosion is a major factor affecting the durability of existing structures, it is necessary to explore the extent of steel corrosion in order to take the necessary measures. Based on non-damaged concrete components or structures, by measuring the performance of concrete-related physical quantities, non-destructive inspection could presume strength, compactness, uniformity and defects of concrete components or structure. Combined with engineering example, non-destructive inspection technique and its application in the degree of steel corrosions inspection have great prospects through further validation.

Exploration into Anticorrosive Property of Antirust Compound-Admixture

This paper studied the influence on corrosion resistant performance through the rust resistance performance tests and the resistance to chloride ion penetration tests. In the tests, four test specimens were prepared: (a) blank sample without corrosion inhibitors or composite admixture; (b) mix 20% composite admixture replacing the cement; (c) mix 2% organic inhibitor replacing the cement; (d) combine 20% composite admixture and 2% organic inhibitor replacing the cement. The results showed that both of the composite admixture and the organic inhibitors had the ability to prevent steel corrosion in concrete structures and had their own advantages respectively. Mixing mineral admixture and inhibitor together had synergy effect and had more obvious anticorrosion effect, which helped the specialized production of antirust compound-admixture to ensure homogeneity of concrete.

3D Numerical modelling of steel corrosion in concrete structures

The paper deals with a 3D numerical model for transient analysis of processes after depassivation of reinforcement in concrete, which are relevant for calculation of corrosion rate. The aim of the study is to investigate the influence of the concrete quality, cracking and water saturation in concrete on the current density. The results show that the corrosion rate is higher in poor quality concrete than in good quality concrete. The model predicts that cracks do not influence corrosion rate for the case where the only influence of the crack is on the rate at which oxygen can reach the steel.

Modeling Steel Corrosion in Concrete Structures - Part 2: A Unified Adaptive Finite Element Model for Simulation of Steel Corrosion

Modeling Steel Corrosion in Concrete Structures - Part 2: A Unified Adaptive Finite Element Model for Simulation of Steel Corrosion

Modeling Steel Corrosion in Concrete Structures - Part 1: A New Inverse Relation between Current Density and Potential for the Cathodic Reaction

Modeling Steel Corrosion in Concrete Structures - Part 1: A New Inverse Relation between Current Density and Potential for the Cathodic Reaction

Formulation of a Nondestructive Technique for Evaluating Steel Corrosion in Concrete Structures

This work was supported by Sustainable Building Research Center of Hanyang University which was supported the SRC/ERC program of MEST (Grant # R11-2005-05601003-0).

A Novel Optical Fiber Sensor for Steel Corrosion in Concrete Structures

Steel corrosion resulting from the penetration of chloride ions or carbon dioxide is a major cause of degradation for reinforced concrete structures,. The objective of the present investigation was to develop a low-cost sensor for steel corrosion, which is based on a very simple physical principle. The flat end of a cut optical fiber is coated with an iron thin film using the ion sputtering technique. Light is then sent into a fiber embedded in concrete and the reflected signal is monitored. Initially, most of the light is reflected by the iron layer. When corrosion occurs to remove the iron layer, a significant portion of the light power will leave the fiber at its exposed end, and the reflected power is greatly reduced. Monitoring of the reflected signal is hence an effective way to assess if the concrete environment at the location of the fiber tip may induce steel corrosion or not. In this paper, first the principle of the corrosion sensor and its fabrication are described. The sensing principle is then verified by experimental results. Sensor packaging for practical installation will be presented and the performance of the packaged sensors is assessed by additional experiments.

Analysis of Chloride Penetration into the Corner Zone of Concrete Structure Member

Chloride penetration into concrete is the main cause of steel corrosion in concrete structures exposed to chloride-rich environments. In general, conditions on the diffusion process are dominant among various penetration mechanisms, such as ionic diffusion, capillary sorption, and so on. In recent analysis of current literature, chloride diffusion is as a simplified one-dimensional diffusion process. However, for the rebar in the corner zone of concrete beam, the diffusion belongs to a two-dimensional diffusion. Based on a galerkin finite element method, a two-dimensional diffusion differential equation is built and solved numerically and the different chloride concentration is compared to one dimensional diffusion and two-dimensional diffusion process. The service life of concrete structure members under two-dimensional chloride penetration is predicted by compared with a critical threshold chloride concentration. Compared with general one-dimensional chloride attack, the service life is considerably reduced in a corner zone due to two-dimension penetration.

Modelling steel corrosion in concrete structures

A comprehensive finite element model for predicting the rate of steel corrosion in concrete structures is developed. The model consists of initiation and propagation stages which are cast in the same time and space domains; i.e., processes which commence in the initiation stage, such as temperature, moisture, chloride ion, and oxygen transport within concrete, continue in the propagation stage while active corrosion occurs contemporaneously. This allows the model to include the effects of changes in exposure conditions during the propagation stage on corrosion and the effects of the corrosion reactions on the properties of concrete. The corrosion rates on steel surface are calculated by solving the Laplace's equation for electrochemical potential with appropriate boundary conditions. These boundary conditions include the relationship between overpotential and current density for the anodic and cathodic regions. Due to the non-linear nature of these boundary conditions, a non-linear solution algorithm is used. The developed model will enable designers to carry out comprehensive sensitivity analyses and to gauge the significance of variations in the values of certain parameters on the rate of corrosion in concrete structures.

Advanced modelling of concrete deterioration due to reinforcement corrosion

A comprehensive model is presented for predicting the rate of steel corrosion in concrete structures and the consequent formation and propagation of cracks around the steel reinforcement. The corrosion model considers both the initiation and the propagation stages of corrosion. Processes commencing in the initiation stage, such as the transport of chloride ions and oxygen within the concrete and variation in temperature and moisture, are assumed to continue in the propagation stage while active corrosion is occurring contemporaneously. This allows the model to include the effects of changes in exposure conditions on the corrosion rate and the effects of the corrosion reactions on the transport properties of concrete. The corrosion rates are calculated by applying the finite-element solution of the Laplace equation for electrochemical potential, with appropriate boundary conditions. Because these boundary conditions are nonlinear, a nonlinear solution algorithm is used. The results of the analysis are compared with available test data, and the comparison is found to be satisfactory. Key words: reinforced concrete, steel corrosion, finite-element modelling, durability.

Modelling steel corrosion in concrete structures

Modelling steel corrosion in concrete structures

Numerical Modeling of Steel Corrosion in Concrete Structures due to Chloride Ion, Oxygen and Water Movement

A comprehensive numerical system is proposed for the attempt to solve the problem of the deterioration of reinforced concrete structures subjected to chloride-induced corrosion. This numerical system was created by combining the physicochemical models related to the migration of corrosion-related substances in concrete, such as chloride ions, oxygen and vapor, and the electrochemical models dealing with the formation of half-cell potential from the viewpoints of macrocell corrosion and corrosion current of RC members under chloride-induced corrosion. Chloride ions concentration, oxygen concentration, water content, current density and the loss of cross-sectional area at any position of the rebar can be calculated by this system.