Corrosion Of Reinforcing Bars Research Articles

Influence of corrosion inhibitors in reinforced concrete – A state of art of review

It is commonly known that reinforced bar corrosion possesses a substantial threat to the endurance of reinforced concrete (RC) structures, particularly in harsh environments. As a result, numerous monitoring and detecting devices have been created to obtain or see the degree of damage to corroded reinforcements within concrete, which cannot be seen with the unaided eye. Corrosion mechanism has also been thoroughly studied throughout the world. The goal of this study is to go through the latest changes in reinforced concrete using corrosion inhibitors and how they are used in the lab and in the field. Inhibitors are chemicals which can stop or postpone the onset of corrosion in concrete reinforced buildings when added to concrete at low concentrations. This review study looks at the various forms of corrosion inhibitors used to concrete, along with how they work and where they are utilised. The study also compares the evaluation studies of effectiveness of admixed inhibitor and migrating inhibitor. Inducing of corrosion inhibitor in concrete by electrochemical injection, electromechanical chlorine extraction procedures, X-ray photoelectron spectroscopy (XPS), and rapid chloride migration procedures were also discussed.

Use of polypropylene fibres to increase the resistance of reinforcement to chloride corrosion in concretes

AbstractConcrete with the addition of polypropylene fibres is more cohesive and has better adhesion, deformability and tightness because the fibres “bind” the concrete matrix together and prevent large pores from forming in the concrete mix and limit the formation and spread of shrinkage cracks. Therefore, it can be assumed that polypropylene fibres affect the effectiveness of the concrete cover as a layer protecting steel bars against corrosion. This article presents the results of tests allowing us to estimate the effect of addition of polypropylene fibres on the reduction of reinforcing bars corrosion in concrete caused by the action of chlorides. Evaluation of the degree of corrosion of the reinforcement was analysed using the electrochemical polarisation galvanostatic pulse technique. The use of such a method allowed for the quantitative estimation of the effect of the addition of polypropylene fibre on the reduction of corrosion activity of the reinforcement in concrete.

Exploration of the Factors Affecting Ground Penetrating Radar Response in Bridge Inspection Applications

Ground Penetrating Radar (GPR) is a nondestructive evaluation technique that is recently employed in various civil engineering applications such as concrete quality evaluations, locating reinforcing rebar, and bridge deck integrity assessments. Previous research has shown that the chloride and moisture content of concrete, corrosion state, and depth of reflecting objects (e.g., steel reinforcing bars) have some impact on the strength of GPR signals. What is not yet clear, however, is to what extent these factors can affect GPR response. This research has sought to quantitatively determine the effects of these factors on the attenuation and the resulting response of GPR signals reflected from reinforcing bars in concrete. The effects of these factors were experimentally demonstrated by analyzing data from four reinforced concrete slabs. Analysis of the processed data showed that attenuation was highly attributed to the depth of the reinforcing bars as compared to the concrete chloride and moisture content, where the amplitude of the reflected signals decreased by 4.5dB for every 25 mm increase in depth as compared to about 1.0 dB reduction in signal amplitude due to the presence of chloride and moisture. Corrosion of reinforcement bars, on the other hand, slightly increased the amplitude of the reflected signals by 1.0 dB.

Experimental study on the effect of concrete strength and corrosion level on bond between steel bar and concrete

Corrosion of the steel reinforcement bars reduces the area of the steel bar and the bond stress between the steel bars and around concrete that decreases the capacity of concrete structures. In this study, the bond stress between steel bar with a diameter of 12mm and concrete was examined with the effect of different corrosion levels and different concrete grades. A steel bar was inserted in a concrete block with a size of 20×20×20cm. The compressive strength of concrete was 25.6MPa, 35.1MPa, and 44.1MPa. These specimens were soaked into solution NaCl 3.5% to accelerate the corrosion process with different corrosion levels in the length of 60mm. The pull-out test was conducted. Results showed that the bond strength of the corroded steel bar was higher than that predicted from CEB-FIP. Slip displacement and the range of slip displacement at the bond strength were reduced when the concrete compressive strength was increased. The rate of bond stress degradation occurred faster with the increment of the corrosion level when the concrete compressive strength was increased.

A closer look at corrosion of steel reinforcement bars in concrete using 3D neutron and X-ray computed tomography

Corrosion of reinforcing bars constitutes the largest threat to the durability of concrete structures. Thus, several studies have investigated the nature of the corrosion products, most using post-mortem analyses. However, corrosion products evolve when in contact with oxygen, hindering result interpretation. This work presents instead a state-of-the-art, non-destructive 3D method for the assessment of corrosion of embedded reinforcements.Multimodal neutron and X-ray tomography was used to observe, non-destructively, the characteristics of the corrosion products in two concrete samples, with the aim of investigating possible benefits of the use of this technique for reinforced concrete structures. One sample was naturally corroded, extracted from an 81-year-old bridge, the other was corroded via the galvanostatic method, resulting in corrosion-induced cracks. Quantitative and qualitative data was acquired, including the iron-to-rust volumetric ratio in macroscopic interfacial voids and the thickness of the corrosion layer at the steel concrete interface. The iron-to-rust volumetric ratio corresponded to large, soluble, corrosion products, forming in environments with low availability of oxygen for both samples.

THE FLEXURAL BEHAVIOR OF CORRODED OFFSHORE RC BEAMS REPAIRED BY DIFFERENT TECHNIQUES

RC beams in a marine environment suffer deteriorations caused by the corrosion of reinforcement. Many researches have investigated this problem, yet few repairs techniques have been developed until now. The purpose of this research is to determine the effect of these deteriorations on the flexural behavior of RC beams. Also investigate rehabilitation of corrosion-damaged RC beams with different repair techniques. The flexural performances of the beams were studied. In this study, flexural test have been carried out to study the influence of reinforcing bar corrosion and cracking on ultimate strength of reinforced concrete beams, bearing capacity and ductility. There were totally 5 RC beams (300 mm × 150 mm × 2200 mm) constructed in this research, 4 of which were corroded by marine environment. The flexural behavior of these beams are studied at one level of corrosion of reinforcement bar. However, with progressive increase in corrosion, the ultimate strength, stiffness and toughness decrease rapidly for RC Beams subjected to flexural loading. The results show that the repair methods could provide better load carrying capacity for the beams with different techniques.

Phase-field simulations of cover cracking in corroded RC beams

Corrosion of steel reinforcement bars is a crucial issue for the reinforced concrete structures. Being one of the most common deterioration mechanisms, corrosion severely affects the serviceability and durability of the structure as the steel reinforcement suffers from a reduction of the cross section and deterioration of the mechanical properties. Additionally, due to the steel oxidation process, residual material is formed, and the volume occupied by the reinforcement increases, leading to cracking and spalling of the concrete cover. A predictive model coupling concrete carbonation process and phase-field approach for brittle fractures is proposed to simulate the carbonation induced corrosion of rebar and the subsequent cracking phenomenon. First, a Fick diffusion law is used to describe the carbon dioxide (CO2) diffusion within the concrete which leads to a generalized corrosion process. As the corrosion evolves, the steel mass loss is converted into expansion strain due to the formation of residual material, and the damage evolution within the concrete cover is determined. After validation against examples from the literature, numerical simulations are performed, presenting a phase-field strategy capable to describe the cover cracking of corroded RC beams.

Examination of Reinforcement Steel Bars Exposed to the Atmosphere

Reinforcement steel bars are often exposed to the atmosphere before use in concrete structures. This exposure results in corrosion of these reinforcement bars. Corrosion of reinforcement bars is a common form of degradation of reinforced concrete structures. The electrochemical attack affects the mechanical properties of steel rebars. This study analysed the effect of exposing reinforcing steel bars to the atmosphere. The bars were divided into two; one part was exposed to the atmosphere for a period of four months during the rainy season while the other was unexposed. Afterwards; some mechanical, corrosion and metallographic tests were carried out on the steel samples. The results obtained showed that the hardness, impact strength and ductility increased with exposure while the yield and tensile strengths decreased with exposure. The exposed bar had high corrosion rates than the unexposed bar in 1M hydrochloric acid (HCl) while in 1M sodium chloride (NaCl), the corrosion rates for both the exposed and unexposed bars did not follow a particular trend

Examination of Reinforcement Steel Bars Exposed to the Atmosphere

Reinforcement steel bars are often exposed to the atmosphere before use in concrete structures. This exposure results in corrosion of these reinforcement bars. Corrosion of reinforcement bars is a common form of degradation of reinforced concrete structures. The electrochemical attack affects the mechanical properties of steel rebars. This study analysed the effect of exposing reinforcing steel bars to the atmosphere. The bars were divided into two; one part was exposed to the atmosphere for a period of four months during the rainy season while the other was unexposed. Afterwards; some mechanical, corrosion and metallographic tests were carried out on the steel samples. The results obtained showed that the hardness, impact strength and ductility increased with exposure while the yield and tensile strengths decreased with exposure. The exposed bar had high corrosion rates than the unexposed bar in 1M hydrochloric acid (HCl) while in 1M sodium chloride (NaCl), the corrosion rates for both the exposed and unexposed bars did not follow a particular trend.

Experimental study of biopolymer in corrosion resistance for industrial exposure condition

Abstract Many RCC structures have been built in the last century but these structures are in need of repair within 10–20 years of its construction. The reason for this premature distress and deterioration points towards corrosion of steel reinforcement bars used in these structures due to weakening of concrete. The enormous number of structures that needs immediate repair and renovation opens up a huge potential for research in this area. The repair work done in a conventional way using normal cement composite did not work. Whereas repair work done with scientific approach using high and technically competent materials (like epoxies) leads to uneconomical solutions and not durable to withstand our tropical climatic conditions. India being a flourished nation with infinite resources giving us a numerous number of bio-polymers that were used in ancient times in ancient construction, if these bio polymers are identified experimentally for their benefits it would give way to eco-friendly economical and long-lasting structures. The use of corrosion inhibitor is one of the most widely used countermeasures, because of their simplicity in applications and is relatively less expensive. The natural bio polymers are organic materials available from selected plants, seeds, fruit extracts. Plant extracts corrosion inhibitors are cheap, non-toxic and environmental friendly. Organic inhibitors offer protection by adsorbing and forming a protective film on the steel surface. Turmeric, Neem extracts in concrete as corrosion inhibitor in different ratio and as a combination are to be studied at depth, as they are commonly available and there is no constraint in getting these resources throughout the year. An eco-friendly, economical, Non-Toxic and user-friendly corrosion inhibitor can be given from this experimental study. The feasibility study has been made and phytochemical analysis results give positive results for a better result giving corrosion inhibitor.

Autonomous Corrosion Assessment of Reinforced Concrete Structures: Feasibility Study.

In this work, technological feasibility of autonomous corrosion assessment of reinforced concrete structures is studied. Corrosion of reinforcement bars (rebar), induced by carbonation or chloride penetration, is one of the leading causes for deterioration of concrete structures throughout the globe. Continuous nondestructive in-service monitoring of carbonation through pH and chloride ion (Cl−) concentration in concrete is indispensable for early detection of corrosion and making appropriate decisions, which ultimately make the lifecycle management of RC structures optimal from resources and safety perspectives. Critical state-of-the-art review of pH and Cl− sensors revealed that the majority of the sensors have high sensitivity, reliability, and stability in concrete environment, though the experiments were carried out for relatively short periods. Among the reviewed works, only three attempted to monitor Cl− wirelessly, albeit over a very short range. As part of the feasibility study, this work recommends the use of internet of things (IoT) and machine learning for autonomous corrosion condition assessment of RC structures.

Predicting the Width of Corrosion-Induced Cracks in Reinforced Concrete Using a Damage Model Based on Fracture Mechanics

Using a finite-element scheme based on a damage model, a numerical system is developed to predict cracks in reinforced concrete beams due to corrosion expansion. The numerical results show that the width of such cracks is affected considerably by (i) the shape of the reinforcing bar, (ii) the presence of stirrups, and (iii) the number of main reinforcement bars. Specimens of reinforced concrete beams are fabricated to simulate those used in the analysis, and we determine how the crack width is related to the amount of the reinforcing bar corrosion through electrolytic corrosion experiments. The experimental results are used to assess the validity of the numerical ones, and the latter are considered to reproduce the former.

Critical Analysis of Experiments on Reinforcing Bar Corrosion in Cracked Concrete

Critical Analysis of Experiments on Reinforcing Bar Corrosion in Cracked Concrete

Experimental Study and Mechanism on the Corrosion of Stressed Reinforcement Bars

In order to understand the influence of the tensile stress on the corrosion of reinforcement bars in civil engineering, the reinforcement bars specimens were put into the liquid corrosion tank made of hydrochloric acid and distilled water by applying the tension stress on the reinforcing frame to carry out rapid corrosion. The corrosion of reinforcement bars under different tension stresses was tested by using electrochemical polarization method. The metallographic examination of reinforcement bars was carried out through the section of reinforcement bars. The corrosion mechanism of the stressed reinforcement bar was tested and analyzed. It can be known from the experimental study: First in the same corrosion condition, the larger the tensile stress is, the faster the corrosion of steel bar will be; Second corrosion current density or corrosion rate are index for evaluating corrosion rate of reinforcement bars with different tensile stresses. Corrosion potential can not be used as an index for evaluating corrosion rate of reinforcement bars with different tensile stresses; Third intercrystalline corrosion occurs inside the reinforcement bar due to micro-defects after rolling and moulding, which directly affects the mechanical properties of reinforcement bar.

Reinforcement corrosion in limestone flash calcined clay cement-based concrete

Limestone calcined clay cement (LC3) concrete has attracted world-wide attention as a newly promising low-carbon concrete. In this study, long-term reinforcement corrosion in LC3 concrete was investigated. Both chloride and carbonation-induced reinforcing bar corrosion were examined. Open circuit corrosion potential, polarization resistance, Tafel constants were monitored at regular intervals up to 500 days. Gravimetric mass loss was measured and compared to the loss of mass calculated using electrochemical methods. The performance of concrete with flash calcined clay and limestone was similar to that of traditional Portland cement concrete in long-term investigation. Traditional corrosion methods and classifications used widely to assess of steel in concrete can be applied to concrete containing LC3 providing a recalibration of polarization resistance range for passitivity condition.

Role of Carbon Dioxide on the Corrosion of Carbon Steel Reinforcing Bar in Simulating Concrete Electrolyte

The main factors that make it possible to get the corrosion of reinforcing steel in concrete are chloride ions and the absorption of carbon dioxide from the environment, and each of them works with a mechanism which destroys the stable immunity of rebar in the concrete. In this work the effect of carbon dioxide content in the artificial concrete solution on the corrosion behavior of carbon steel reinforcing bar (CSRB) was studied, potentiostatically using CO2 stream gas at 6 level of concentrations; 0.03 to 2.0 weight percent, and the effect of rising electrolyte temperature was also followed in the range 20 to 50ᴼ C. Tafel plots and cyclic polarization procedures were obeyed to investigate the corrosion parameters and pitting susceptibility respectively. The change in the microstructure and morphology of the CSRB after polarization in the simulate concrete solution was studied using optical and atomic force microscopes. The results show that the corrosion rate of the CSRB in artificial concrete greatly increases with the existence of CO2 gas and highly depends on its concentration in the range 0.03 to 2.0% .No sign for pitting corrosion is recorded at all CO2 concentrations and the general corrosion is the main problem in the conditions under consideration.

Study on Corrosion of Reinforcement Bars in Ceramic Recycled Gradient Concrete

In view of the problem that a reinforced-recycled-concrete structure is prone to crack due to steel corrosion in saline soil area in Western China, a kind of ceramic recycled gradient reinforced co...

Combined application of novel electromagnetic sensors and acoustic emission apparatus to monitor corrosion process of reinforced bars in concrete

Reinforced bar corrosion is a primary reason for performance deterioration of reinforced concrete (RC) structures. Corrosion monitoring of reinforced bars in concrete is a key point to evaluate the durability and the remaining service life of structures, especially in marine environments. Non-destructive tests (NDTs) have been developed as critical methods to assess damage levels inside concrete without external damage based on physical characterization (e.g., electromagnetic response, acoustic signals, etc.). This paper provides a novel idea where home-made electromagnetic (EM) sensors and an acoustic emission (AE) apparatus are combined in order to monitor the entire corrosion process of reinforced concrete beams; meanwhile, a home-made electromagnetic sensor is also upgraded and introduced in this paper. The result shows that it is an excellent option to jointly utilize two kinds of monitoring apparatus to monitor signals from corrosion initiation and subsequent cracking, respectively, based on their own physical performances. Moreover, the reliability of monitoring signals is also highlighted in this paper.

Experimental investigation on seismic behavior of corroded RC columns under artificial climate environment and electrochemical chloride extraction: A comparative study

Corrosion of reinforcement bars can cause reinforced concrete (RC) columns more vulnerable under seismic loads. In this study, the seismic behavior of corroded RC columns was experimentally studied with a focus on the comparison between two different accelerated corrosion techniques by using artificial climate environment (ACE) and electrochemical chloride extraction (ECE). To do this, six RC square columns were designed and fabricated as the test specimens. The test specimens were categorized into two groups with a low level and a high level of axial compression ratio (i.e., 0.1 and 0.45), respectively, and each group includes three test specimens, i.e., an uncorroded column and two corroded columns under ACE and ECE techniques. An X-ray diffraction approach was used to examine the major ingredients of corrosion products attached on the corroded reinforcement bars under ACE and ECE techniques. The column specimens were subjected to repeated cyclic loadings, and the failure modes, hysteresis and backbone curves, stiffness degradation, ductility level and energy dissipation of the specimens corroded under different techniques were compared. The results show that, under a consistent target corrosion level, the ECE corrosion technique can cause more significant damage to the corroded RC columns than the ACE corrosion technique, leading to a change of failure mode and worse hysteretic performance.

Investigation on chloride penetration in concrete mixes of different cement replacement percentages with fly ash and silica fume

Generally, the life of R.C structure is expected to be 100 years, but today’s structures are failing in 30 years due to corrosion of reinforced steel. One of the major problem to concrete from environmental attack is chloride ingress which leads to corrosion of reinforcement bars further leads to decrease of its strength and service life of structure. The focus of the work is on the chloride ion concentration at different depth in non-steady diffusion. Nine concrete mixes with different percentages of supplementary cementitious materials and water to cementitious ratios of 0.3, 0.4, & 0.5 were casted and compared with convention mixes (without replacing cement). The replacing of cement with different percentages of 30%, 50% & 70% and with 5% silica fume. Strength of concrete tested for 28, 56 & 90 days. Specimens were conducted ponding test for 6 & 12 weeks of 3.5% NaCl solution. Chemical analysis is carried out for predicting chloride concentration in concrete at different depths from surface exposed NaCl specimens.