Corrosion Of Steel In Concrete Research Articles

Social Parameter’s Role in BEM-PSO-Based Inverse Analysis for Locating Corrosion of Reinforced Concrete

The objective of this research is to investigate the effect of social parameter on the performance of boundary element inverse analysis (BEIA) to determine the location of reinforcing steel corrosion in concrete. BEIA was constructed by integrating the Boundary Element Method (BEM) and Particle Swarm Optimization (PSO) (PSO). BEM was used to calculate the corrosion potential on the whole surface of reinforced concrete. The cost function for detecting corrosion of reinforcing steel in concrete was evaluated using PSO. BEIA was conducted with 15 electrical potential data on the surface of reinforced concrete as a reference, such as from half-cell potential measurement. Numerical simulations of reinforced concrete with a single reinforcement reveal a difference in the speed of BEIA in locating corrosion sites. The higher the social parameter value, the faster the particles tend to migrate. However, if the parameter value is too high, the number of iterations required for the particles to converge increases, which has a negative effect on locating the corrosion point. Consequently, the variation of the social parameter affects the performance of BEIA in detecting the location of corrosion in reinforced concrete.

Analysis of Circumferential and Longitudinal Non-Uniformity of Steel Corrosion in Concrete Subjected to Mechanical Load

Reinforcement corrosion significantly impacts the service life of reinforced concrete structures. The present study investigates the circumferential and longitudinal non-uniformity of steel corrosion in concrete subjected to mechanical load. Results indicate that, in the case of steel corrosion in concrete subjected to mechanical load, the distribution of rust layer thickness around the perimeter of the steel bar is fitted well with a Gaussian distribution. As the corrosion rate gradually increases, the uniform coefficient is linearly proportional to the minimum thickness of the rust layer. With respect to the longitudinal non-uniformity of steel corrosion, load-induced transverse cracks have a significant impact on the non-uniformity of corrosion, leading to the formation of rust peaks near the locations of transverse cracks. In the vicinity of each rust peak, the corrosion rate of the steel bar follows a Gaussian distribution. With respect to the non-uniformity of corrosion along the longitudinal rebar, a Gumbel distribution is identified to fit well, both in the cases of the non-stressed section and the pure bending section, although with dissimilar non-uniform parameters. Crack coefficients (α and β) are introduced to describe the influence of transverse cracks on the longitudinal non-uniformity of steel corrosion.

Identification of carbonation‐induced corrosion of steel in concrete by electrochemical testing

AbstractCarbonation‐induced corrosion of steel in concrete can allow for premature degradation of structures. Corrosion probes in health monitoring systems can assess concrete carbonation and steel corrosion rates. The electrochemical noise (EN) technique has advantages for corrosion sensing. Instrumented concrete columns were fitted with a carbonation chamber for accelerated testing. EN was assessed through statistical evaluation of noise time signatures, noise resistance, and spectral analysis. The mean noise potential for the electrodes showed electronegative potential and correspondingly high rms noise current, indicative of corrosion activation in carbonated concrete. The estimated corrosion rates obtained from the noise impedance were comparable to those resolved from the polarization resistance and noise resistance. The shot noise analysis indicated isolated spontaneous noise events associated with the activation of local steel anodes. The outcomes of the testing indicate that the placement of low‐cost sensors and passive EN measurements can be used to monitor the onset of carbonation‐induced corrosion of steel in concrete and provide estimates on corrosion rates.

Experimental and numerical investigation on the effect of cracks on chloride diffusion and steel corrosion in concrete

Various environmental factors limit the durability of reinforced concrete. Chloride ion is the main factor causing rebar corrosion in concrete. It attacks the rebar surface with its strong diffusion ability, destroying the passive film and accelerating structural damage. Cracks in the structure also provide natural channels for chloride ion diffusion, increasing the rebar corrosion rate and reducing the structure service life. In this study, the influences of water–cement ratio, age, and crack width, depth, and spacing on chloride diffusion and steel corrosion were explored using the silver nitrate colourimetric method, X-ray diffraction, COMSOL finite element simulation, polarisation curve method, and electrochemical impedance spectroscopy. The rationality of the finite element simulation of the influence of cracks on chloride diffusion was verified, and the influence of chloride on reinforcement corrosion was analysed. This study provides a theoretical basis for optimising the modelling of chloride diffusion in concrete with cracks and improving the understanding of the damage evolution mechanism of cracks.

Monitoring and Accelerating Methods of Corrosion for Reinforced Concrete: A Review

AbstractCorrosion is the irreversible, interfacial reaction of metals in the presence of an electrochemical environment which ultimately results in the deterioration of metals. Corrosion of reinforcement is the major problem in the reinforced concrete (RC) structure. Corrosion of reinforcement is a slow process because of the protective layer of concrete. Even in a severely corrosive environment corrosion process takes time to be initiated and propagated. Since to carry out research work, some techniques are required to accelerate the corrosion process in the shortest period. To overcome this problem, in the past, many researchers use a different method to accelerate the corrosion of steel in concrete. In this paper, a review is presented of various techniques used for accelerated corrosion testing. The suitability of reviewed methods on corrosion acceleration for several research works is presented. After that few case studies review to make use of various predicted empirical models and an experimental technique for predicting corrosion rate and the assessment of the remaining life of the structure. And finally, the paper is concluded by comparing the natural method of corrosion and the accelerated method of corrosion and the future scope of accelerated corrosion.

Corrosion of carbon steel rebar in binary blended concrete with accelerated chloride transport

Samples with two different binary blended concrete mixes were prepared, one containing cement replacement of 50% slag (referred here as SL mix) and the other containing cement replacement of 20% fly ash (termed here as FA mix). The water to cementitious ratio used to produce concrete specimens was 0.41. On the top surface of each specimen, various reservoir lengths that ranged from 2.5 cm to 17.5 cm were fitted, and these reservoirs were filled with a 10% NaCl solution. Electromigration was used to accelerate the transport of chlorides, with an applied potential of 9 V at first, and subsequently reduced to 3 V after about a week. The electromigration was applied for a short period (few weeks to a couple of months). For a period of about 1100 days, the corrosion related parameters such as concrete solution resistance, rebar potential, and corrosion current were monitored via the rebar potential measurements, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) measurements, the latter used only to obtain the solution resistance. The corrosion current values determined through experimental observations were then converted to mass loss using Faraday’s law. The readings of corrosion current values (last 7 sets of readings) as well as the calculated mass loss values were found to be larger for the rebars embedded in specimens prepared with SL mix, followed by rebars embedded in specimens prepared with FA mix. Corrosion current and calculated mass loss values in general tended to increase with increasing solution reservoir lengths. No cracks or corrosion products that reached the surface of the concrete were observed on the specimens for the duration of the reported monitored propagation period. This study offers a framework for future studies on accelerated steel corrosion in concrete.

Deep learning-based extraction and quantification of features in XCT images of steel corrosion in concrete

The corrosion of rebars in concrete has been regarded as one of the most predominant factors for the degradation of reinforced concrete (RC) structures. The accurate predictions of corrosion damages are the basis for the safety assessment of in-service RC structures and the enhancement of new structure designs. X-ray computed tomography (XCT), known for its non-destructive capabilities, has been widely utilized to understand the corrosion process inside the concrete, offering three-dimensional (3D) visualization and aiding in the identification of the parameters in the predictive model of steel corrosion. This study uses U-Net, a deep learning network, to detect various phases of steel corrosion evolution in concrete, including the identification of rebar, corrosion products, pores, cement mortar, and corrosion-induced cracking. A galvanostatic accelerated corrosion test was conducted to simulate rebar corrosion within the mortar. The XCT test was performed, producing a series of XCT images that revealed the corrosion-induced cracks in the concrete. This set of images formed a comprehensive training database for the U-Net model. The performance of the model was significantly improved by data augmentation within the training dataset, thereby enabling it to recognize corrosion-induced cracking and pores. The U-Net model proved effective in accurately segmenting the XCT images into different phases, demonstrating a high accuracy rate of 99.18% on the validation dataset. A mean Intersection over Union (IoU) of 82.1% and a mean F1 score of 89.1% are observed on the test dataset, showing superior segmentation performance on XCT images. This significant advancement has automated the process of visualizing and 3D reconstructing the steel corrosion process inside the concrete. Concurrently, it has enabled the quantification of the volumetric expansion coefficient of corrosion products. The findings reveal spatial and temporal variations in this coefficient due to the migration of the corrosion product through the cracks.

Effects of bonding on Fiber Bragg Grating (FBG) sensor for monitoring steel corrosion condition in concretes

Steel corrosion in concrete is harmful but invisible. Until now, it is still very hard to measure the steel corrosion condition by non-destructive method accurately. In this paper, Fiber Bragg Grating (FBG) sensors include single and three grating sensors, are proposed to bond with steel bar and embed in concrete for monitoring the steel corrosion condition. The steel corrosion condition is evaluated by the corrosion ratio and volume expansion coefficients of steel, which are derived from the wavelength shift of FBG. Bonding materials and bonding ways are investigated in detail for improving the accuracy of FBG sensors. The mechanism of bonding effects on FBG sensor for optimizing the accuracy, has been discussed. The results suggested that the steel corrosion condition is successfully monitored by calculating the corrosion ratio of 2.02–4.24%, and volume expansion coefficient of 2.18–2.65 in this test. The research work is more quantify than the traditional methods for monitoring the steel corrosion condition in concretes. It is helpful for ensuring the safety operation of infrastructures efficiently.

A two-level strategy to assess the bearing capacity of corroded structures via long-gauge fiber-optic sensors

Corrosion of steel in concrete is the most common deterioration mechanism for structures located in aggressive environments. This research proposes a two-level strategy to assess the residual bearing capacity of corroded structures by detecting and quantifying corrosion via a new kind of long-gauge fiber Bragg grating (FBG) sensors. Compared with the traditional point strain gauges, this new sensor has been developed for both local and global structural monitoring by measuring the averaged strain within a long gauge length. According to the mechanical relationship between the moving load and the long-gauge strain influence line (IL), an IL aera-based difference index is established to identify the presence of the damage and the corrosion is quantified in terms of reduction of sectional area of reinforcement (Level 1); and then an elaborate finite element (FE) model is built to perform failure analysis to assess the residual bearing capacity by modifying the material constitutive model according to the corrosion condition (Level 2). A laboratory experiment is conducted to verify the effectiveness and accuracy of the proposed method.

Measurements on macrocells made of segmented reinforcement in concrete showing environmental impacts on corrosion of steel in concrete

AbstractCorrosion of steel in concrete can be characterized by measuring the galvanic current density when a macrocell is established. On nonpolarized steel, however, other electrochemical techniques like linear polarization resistance measurements may be used to characterize the electrochemical state of steel in concrete. On existing structures with their large dimensions and local differences in exposure conditions, local differences in the electrochemical state of the embedded reinforcement are established, leading to potential differences along the reinforcement and galvanic currents flowing. When it is possible to isolate anodic areas from the rest of the reinforcement, both galvanic current measurements, determination of polarization resistance on the separated anodic areas and the driving force between the anodic segments and the reinforcement are possible to obtain. In this work, this procedure is discussed and verified on a field structure on anodic areas caused by cracks in the concrete overlay and the results thereof are presented.

Mechanism of inhibitors in control of corrosion of steel in concrete

Reinforced concrete is the most abundantly used material in the infrastructure industry. Corrosion of reinforcing steel is the most critical and significant problem that the building industry faces. This durability issue is primarily caused due to chloride attack or carbonation of concrete. Among other techniques used in producing high-performance concrete, the use of corrosion inhibitors is the most attractive from the view of cost and ease of application. There is a diverse range of available corrosion inhibitors that are classified based on their origin, mechanism of protection, and composition. This paper covers a critical overview of the different mechanisms of corrosion protection offered by corrosion inhibitors. Furthermore, the stricter enforcement of environmental rules has prompted and inspired researchers to focus on developing non-toxic and ecologically acceptable corrosion inhibitors. This paper also gives a brief account of the ecological sustainability and toxicity issues concerning the commercially available inhibitors and the versatility and effectiveness of green corrosion inhibitors compared to synthetic corrosion inhibitors. This account of corrosion inhibitors attempts to contribute towards developing awareness and understanding of the primary mechanism of protection and the use of innovative and green materials to increase the service life of steel-reinforced concrete.

Effect of fly ash and red mud on strength and electrochemical properties of seawater mixed concrete

The utilisation of seawater (SW) for making concrete appears to be a reasonable alternative to conserve freshwater. This paper investigates the possibility of making seawater mixed concrete (SMC) using cementitious replacement of fly ash (FA) and red mud (RM) to offset the adverse effects of SW in concrete. FA was added by replacing from 10% to 40% by weight of cement and RM from 5% to 20% and compressive strength, split tensile strength and electrochemical properties of concrete were evaluated for different mixes for 7, 28 and 90 days of testing. Analysis of variance method was used to identify the influences of FA, RM and concrete testing age on the SMC properties. The best mix was then finalised using the response surface method (RSM). It was observed that RM and especially FA were very effective in improving SW concrete properties, that is, increasing mechanical strength and controlling corrosion of steel in concrete. The results showed that to successfully utilise SW for making concrete, the best results at the testing age of 90 days were obtained on replacing cement with approximately 40% FA. The novel mix showed approximately 23% increase in compressive strength and 12% increase in tensile strength compared to SWM concrete. In addition, the novel mix electrical resistivity is around 60 kΩcm showing it to be in low corrosion zone.

Determination of rust formation to cracking at the steel–concrete interface by corrosion of steel in concrete

In this study, a development of the rust formation was modelled to quantify the structural impact in steel reinforced concrete. The interfacial gap, cover depth and diameter of steel rebar were taken for variables in modelling. It was found that the interfacial gap was the most influencing on the structural limit at steel corrosion, followed by steel diameter and cover depth. At 75 mm of cover depth with 20 mm of the steel diameter, the rust amount to reach yielding accounted for 2.66–11.58 µm to 1–10 µm of the interfacial gap, while 16.95–27.69 µm to the equivalent rust formation.

Performance evaluation of acrylate terpolymer based coating on anti-carbonation

PurposeThe purpose of this study is to examine how well reinforced concrete structures can be shielded against concrete carbonation using anti-carbonation coatings based on synthetic polymer.Design/methodology/approachApplying free radical polymerization, an acrylate terpolymer emulsion that a surfactant had stabilized was created. A thermogravimetric analysis, minimum film-forming temperature, Fourier transform infrared spectroscopy and particle size distribution are used to characterize the prepared eco-friendly water base acrylate terpolymer emulsion. Using three different percentages of the acrylate terpolymer emulsion produced, 35%, 45% and 55%, the anti-carbonation coating was formed. Tensile strength, tensile strain, elongation, crack-bridging ability, carbon dioxide permeability, chloride ion diffusion, average pull-off adhesion strength, water vapor transmission, gloss, wet scrub resistance, QUV/weathering and storage stability are the characteristics of the anti-carbonation coating.FindingsThe formulated acrylate terpolymer emulsion enhances anti-carbonation coating performance in CO2 permeability, Cl-diffusion, crack bridging, pull-off adhesion strength and water vapor transmission. The formed coating based on the formulated acrylate terpolymer emulsion performed better than its commercial counterpart.Practical implicationsTo protect the steel embedded in concrete from corrosion and increase the life span of concrete, the surface of cement is treated with an anti-carbonation coating based on synthetic acrylate terpolymer emulsion.Social implicationsIn addition to saving lives from building collapse, it maintains the infrastructure for the long run.Originality/valueThe anti-carbonation coating, which is based on the synthetic acrylate terpolymer emulsion, is environmentally benign and stops the entry of carbon dioxide and chlorides, which are the main causes of steel corrosion in concrete.

Big milestones in the study of steel corrosion in concrete

AbstractRebar corrosion in concrete has been neglected for a long time in the scientific and technical literature, as reinforced concrete was considered an “eternal” material. Only during the 60s, and more during the 70s and the 80s, several research groups and many corrosion schools gave important contributions. An important impact was also achieved by Italian researchers thanks to the Universities of Roma, Napoli, Ancona, Ferrara, Bergamo, and Politecnico di Milano, where professor Pietro Pedeferri and his school contributed to the study of stainless steel reinforcement, corrosion inhibitors, service life modeling, cathodic protection and cathodic prevention, the latter proposed by Pedeferri in the early 90s. The paper is dedicated to the memory of Pietro Pedeferri (1938–2008) and Luca Bertolini (1966–2017).

The Feasibility of Using Bipolar Electrochemistry to Study Pitting and Crevice Corrosion of Stainless Steels in Cementitious Materials

The durability of carbon steel reinforced concrete infrastructure is often limited by rate of corrosion damage progression. Over the past couple of decades, corrosion-resistant alloys, such as stainless steels (SS), have garnered attention as a potential way to address the durability of reinforced concrete exposed to aggressive marine environments. However, there are currently no models available to accurately forecast corrosion of stainless-steel reinforced infrastructure and durability projections for carbon steel may not consider the necessary mechanistic steps.Traditional corrosion durability projections adopt the classic two stage model considering the time prior to and following corrosion initiation often distinguished by the point in time where enough chlorides have accumulated at the steel surface to exceed the chloride concentration required to initiate corrosion.[1] Such models do not consider the evolution of pitting or crevice corrosion and the potential for progression to more widespread corrosion. Therefore, research is required to first identify the expected corrosion damage morphology of stainless steels in concrete and then to formulate a theoretical framework that can be used to describe accurately its progression provided expected exposure conditions. This work attempts to develop an efficient yet informative method to study pitting corrosion evolution of steel in concrete with the objective of identifying the role of the cement pore structure on damage evolution and pit or crevice stability.Recently, bipolar electrochemistry has been used to identify potential-kinetic-corrosion damage mode relationships from single measurements on ferritic [2] and duplex stainless steels.[3] Bi-polar electrochemistry (BPE) comprises indirect dc polarization of a conductive element usually immersed in an electrolyte in cases where direct contact to the elements need to be avoided. In application to pitting corrosion studies, BPE followed by post exposure 3D surface metrology can provide pitting characteristics as a function of applied potential from a single experiment. In this work various BPE configurations including single and split electrodes are used to assess the feasible in applying a suitable potential distribution on steel plate specimens that have a thin cement overlay. A finite element model was developed to simulate the applied potential distribution considering the cell geometry and interfacial kinetics. The corrosion damage morphology and the pitting characteristics obtained will be compared to that of chloride-ponded SS reinforced concrete beams to uncover mechanistic insight on SS corrosion damage evolution. Tuutti, K: Corrosion of steel in concrete. 1982, Stockholm. Swedish Cement and Concrete Research Institute, ISSN 0346-6906. Royal Institute of Technology, Stockholm. Department of Building MaterialsZhou, Yiqi, and Dirk Lars Engelberg. "On the application of bipolar electrochemistry to characterise the localised corrosion behaviour of type 420 ferritic stainless steel." Metals10, no. 6 (2020): 794.Zhou, Yiqi, and Dirk Lars Engelberg. "Fast testing of ambient temperature pitting corrosion in type 2205 duplex stainless steel by bipolar electrochemistry experiments." Electrochemistry Communications117 (2020): 106779.

Atomic scale insight into the mechanisms of chloride induced steel corrosion in concrete

Chloride (Cl) induced steel corrosion is a major cause of durability issues of reinforced concrete (RC) structures and causes a large economic loss every year. Understanding the mechanisms of Cl induced steel corrosion in concrete is of great importance to develop anti-corrosion methods and further lowers down the repair and strengthening frequency and cost. Hence, the nature of steel depassivation and corrosion induced by Cl at atomic scale was revealed through the density functional theory (DFT) calculations to better understand the Cl induced corrosion mechanism. The results indicated that Cl species weakened the bonding of oxygen (O) with outer iron (Fe) atoms while enhanced the hybridization of O with inner Fe atoms, thus induced the breakdown of passive films. Besides, Cl facilitated the charge loss of outer Fe atoms and improved the interactions of water molecular (H2O) with these Fe atoms. When co-adsorption with O atom, hydroxyl (OH) generated by dissociative adsorption of H2O enhanced the charge loss of outer Fe atoms. Then OH strongly bonded with the neighboring Fe atoms to form the initial corrosion products, iron hydroxides (Fe-OH). The above DFT calculations are consistent with the experimental results about the steel depassivation and corrosion processes in concrete and hopefully these results can guide the anti-corrosion design of RC structures.

Evaluation of Nonuniform Corrosion of Steel in Concrete Based on Two-Yoke Magnetic Sensor

Evaluation of Nonuniform Corrosion of Steel in Concrete Based on Two-Yoke Magnetic Sensor

The Role of Cracks in Chloride-Induced Corrosion of Carbon Steel in Concrete—Review

The majority of works in the field of chloride-indued corrosion of steel in concrete are focused on the cracks formed by the corrosion products. However, the number of studies on the influence of cracks (pre-cracked concrete) on corrosion is limited. Cracks create preferential/free paths for the penetration of chlorides, water, and oxygen into concrete; thus, the presence of cracks in concrete can intensify chloride-induced corrosion of steel reinforcement. This paper presents a review of the effects of cracking on the corrosion of steel in concrete. It was widely reported in the reviewed papers that cracks have a negative impact on concrete durability. They influence the chloride penetration and the chloride-induced corrosion of reinforcement in terms of the initiation and propagation stages. This influence is a complex function of many factors, including mix design, exposure conditions, crack frequency, crack orientation, crack width, and cover depth. Although there is a general agreement on the effects of cracks on the initiation of corrosion, the role of cracks and their widths on the propagation of corrosion in the long term is still under debate.

Beyond the chloride threshold concept for predicting corrosion of steel in concrete

All existing models to forecast the corrosion performance of reinforced concrete structures exposed to chloride environments are based on one common theoretical concept, namely, a chloride threshold, as a sharply defined trigger for corrosion, followed by a period of active corrosion. We critically review the resulting treatment of corrosion initiation and propagation as two distinct, successive stages. We conclude that this concept presents a major barrier for developing reliable corrosion forecast models, and that a new approach is needed. In reality, steel corrosion in concrete is a continuous process, that is, rarely separable into uncoupled, sequential phases. We propose that the focus be placed on the quantification of the time- and space-variant corrosion rate from the moment steel is placed in concrete until it reaches the end of the service life. To achieve this, a multi-scale and multi-disciplinary approach is required to combine the scientific and practical contributions from materials science, corrosion science, cement/concrete research, and structural engineering.