Accelerated Corrosion Method Research Articles

Experimental investigation of the seismic performance of corroded reinforced concrete coupling beams

In this study, a seismic performance assessment of six reinforced concrete (RC) coupling beam specimens with accelerated corrosion is conducted by combining accelerated corrosion methods with quasistatic loading tests. A detailed comparison of the corrosion damage, failure modes, and mechanical performance differences of the coupling beam specimens under different corrosion levels is presented. The degradation patterns of the coupling beam seismic performance are revealed through analyses of the hysteresis behavior, stiffness degradation, energy dissipation capacity, and proportions of bending, shear, and slip deformations in relation to the corrosion level. The experimental results indicate that with increasing corrosion level, the load-carrying, deformation, and energy dissipation capacities of the coupling beams continuously decrease. The cracking pattern of corrosion-induced cracks is influenced by the reinforcement arrangement, with diagonal reinforcement causing cracks to propagate diagonally. The nonuniform distribution of corrosion leads to asymmetric loading in coupling beam specimens with higher corrosion ratios, significantly weakening the load-carrying and energy dissipation capacities and making the specimens more prone to sudden brittle shear failure without warning. Corrosion-induced damage degrades the shear capacity of the coupling beams, increasing the proportion of shear deformation.

Investigation of the dynamic mechanical response of corroded ultra-high performance fiber reinforced concrete (UHPFRC) with initial defects

This study addresses the dynamic mechanical response of the corroded ultra-high-performance fiber-reinforced concrete (UHPFRC) with initial defects, considering the possibility of corrosion deterioration induced by various pre-existing cracks during the long-term service life. For this purpose, an integrated accelerated corrosion method and Split Hopkinson Pressure Bar (SHPB)/high-speed camera etc. techniques are employed. Results show that increasing pre-impacting damage promotes the crack density and maximum width by 32.4%–62.3 % and 1.11–1.8 times, respectively. In terms of mechanical properties, coupling damages of initial defects and corrosion have adverse effects on the dynamic mechanical response. Typical fib Model Code 2010 applies to predict the DIF evolution of the corroded UHPFRC with initial defects. Numerous shear cracks are created at an angle along the weak interface as the corroded specimens with initial defects are again subjected to axial loading, revealing the associated failure mechanism. These results shed light on the dynamic response of corroded UHPFRC containing various initial defects and the failure mechanism gives some reference to service status evaluation.

Reviewing the progress of corrosion fatigue research on marine structures

This paper reviews the state-of-the-art progress of research into corrosion fatigue on marine structures, both theoretical and experimental. This includes corrosion fatigue life prediction models/methods, load–environment interaction/coupling test methods, accelerated corrosion methods in corrosion fatigue testing, fatigue crack measurement, and corrosion fatigue life assessment in the whole life period. To date, some theoretical models and methods for predicting the corrosion fatigue life of metallic materials or structures have been proposed and applied. Meanwhile, load–environment interaction/coupling testing on metallic material specimens has been maturely developed and widely applied. Some newly developed corrosion fatigue theoretical and experimental methods, based on data-driven machine learning and at-sea monitoring, have received preliminary application. This review of accelerated corrosion methods, fatigue crack measurement methods, and corrosion fatigue life assessment for marine structures in the whole-life period has been undertaken by extensive reference to relevant studies conducted worldwide. Challenges and recommendations for further developing and improving corrosion fatigue assessment methods and test techniques are also reported and discussed.

Corrosion effects on bond strength in reinforced concrete with fly ash

Reinforcing steel bars provides additional strength and ductility to concrete by forming a strong bond with the concrete matrix. Corrosion of steel bars can significantly reduce the bonding effect between the steel bar and concrete, which can compromise the structural integrity and durability of reinforced concrete structures. An experimental investigation was performed to examine the influence of fly ash (FA) and corrosion on concrete–steel bond behavior. The accelerated corrosion method was employed to obtain the desired level of corrosion. The FA content, corrosion percentage, and presence of stirrups were considered significant factors influencing bond behavior. The bond–slip curves and bond toughness were used to discuss bond behaviors. The findings indicated that mild corrosion (below 2.5%) can enhance concrete–steel bond performance, and the addition of 20% FA leads to higher ultimate bond strength (τu ), significantly mitigating the decrease in bond strength caused by severe rebar corrosion. Also, this study analyzed the influence of stirrups on the bond strength of FA concrete and had a nearly insignificant effect compared to regular concrete. The results and discussions of the present study carry significant importance in the establishment of a bond–slip constitutive model under multifactor coupling conditions. Furthermore, it offers valuable insights into the design of engineering structures.

Exploratory study on experimental and prediction based stress-strain behaviour of corroded prestressing steel strands

Prestressing steel strands have been extensively used in recent years due to the increased popularity of prestressed concrete structures. However, the corrosion of strands has a detrimental effect on these structures. This necessitates a detailed investigation of the mechanical properties of the corroded strands and to understand their influence on the strength of these structures. Therefore, in this paper, a systematic attempt has been made to study the mechanical properties of corroded steel strands corroded using the accelerated corrosion method. Initially, the tensile test was conducted on these corroded steel strands to study the mechanical properties of the strands and X-ray diffraction analysis was done on the corrosion products of these corroded steel strands. Then, resilient backpropagation with backtracking neural network based prediction models were developed to predict the ultimate strength of the corroded strands. The experimental results showed that an increase in the corrosion level reduces the ultimate stress, yield stress, breaking stress and the corresponding strains of the strand. The proposed prediction models give optimum results of cost functions for ultimate stress and ultimate strain predictions. The comparison study of ultimate stress-strain results obtained from the proposed prediction models showed remarkable performance with the experimental results.

Evaluation of soil accelerated corrosion of typical grounding materials used for electrical equipment

Abstract At present, research methods for soil corrosion include sample weight loss methods, physical and chemical properties research, electrochemical research, indoor accelerated corrosion tests, etc. However, most existing soil corrosion evaluation methods have many drawbacks, such as high research costs, long experimental cycles, long results transformation cycles, and significant environmental limitations. In this paper, based on the electrochemical test results of environmental corrosion factors using typical grounding materials, a corrosion simulation solution load spectrum and an accelerated corrosion experimental system corresponding to the soil corrosion environment level were established. The accelerated corrosion samples were thoroughly studied and analyzed using macroscopic morphology observation, microscopic morphology analysis, and energy spectrum analysis. The results show that the soil accelerated corrosion method has strong stability and small deviation, which applies to the study of accelerated corrosion in the soil environment of grounding materials.

Experimental and Analytical Investigation of Moment-Carrying Capacities of Reinforced Concrete Frame Systems Corroded by Accelerated Corrosion Method

Technical investigations carried out after the devastating earthquakes in Turkey in the last 25 years show that one of the main causes of damage to reinforced concrete structures is reinforcement bar corrosion. The deterioration caused by reinforcement corrosion in reinforced concrete elements reduces the parameters that define the performance level of the structure, such as ductility, stiffness, bond-slip relationship, load carrying capacity, and energy absorption capacity. Therefore, determining the specified performance levels of reinforced concrete structures exposed to corrosion before any seismic activity occurs is of great importance in preventing loss of life and property. Cross-section behavior in reinforced concrete structures represents the load-bearing element behavior In order to accurately determine the section behavior, the Moment-Curvature relationship must be defined. In this study, the structural behavior of reinforced concrete frames exposed to corrosion was examined experimentally and analytically. For this purpose, 4 of the 5 reinforced concrete frame specimens constructed were corroded at different ratios using the accelerated corrosion method. After the corrosion process was completed, in the experimental part of the study, all specimens were tested under the effect of a 20% constant axial load and reversal-cyclic loading. In the analytical study, as a result of the cross-sectional analyzes carried out by taking into account the material-mechanical properties changing with the effect of corrosion, it was determined that the calculated moment values were in high predicted with the experimentally measured moment values.

Autonomous detection of steel corrosion spatial variability in reinforced concrete using X-ray technology and deep learning-based semantic segmentation

Correctly determining the spatial distribution of steel corrosion within a structural member is critical for estimating the remaining service life of deteriorating reinforced concrete (RC) structures. While X-ray technology serves as a nondestructive inspection method, existing challenges persist, particularly in semi-automated corrosion boundary detection. This paper describes a deep learning-based semantic segmentation framework to autonomously detect X-ray images associated with RC, facilitating the visualization of nonuniform steel corrosion distribution. X-ray images were collected from a comprehensive experiment using RC specimens with various structural details by two accelerated corrosion methods. Four deep learning models were constructed, trained, and compared based on the database containing the original X-ray images and the corresponding pixel-level labels. The results demonstrate that the proposed autonomous detection method can segment uncorroded steel at a very high level of global accuracy without time-consuming work, outperforming traditional methods in terms of both accuracy and efficiency.

Seismic performance of corroded prefabricated column-footing joint with grouted splice sleeve connection: Experiment and simulation

Steel corrosion is a critical factor in the seismic performance degradation of prefabricated concrete structures. In this study, the constant current accelerated corrosion method was employed to achieve targeted corrosion levels in steel bars within prefabricated column-footing joints connected by a grouted splice sleeve (GSS). Following that, a quasi-static cyclic experiment and numerical simulation method were employed to investigate the seismic performance of the specimens under various corrosion levels. Seismic performance indicators of specimens including the hysteresis curves, skeleton curves, bearing capacity, ductility coefficient, stiffness, and cumulative energy dissipation are examined. The results demonstrate that the failure modes of all column-footing joints are flexural failures. Specimens with steel bar corrosion levels below 14.1 % show negligible impact on the seismic performance. However, as the corrosion level increases, both the bearing capacity and cumulative energy dissipation capacity of the specimens significantly decrease. The horizontal displacement and ultimate displacement corresponding to the maximum bearing capacity are only 50.5 % and 45.2 %, respectively, compared to the non-corroded specimen. Additionally, a refined finite element model of prefabricated column-footing joints with GSS connections under different corrosion levels is developed and the hysteresis and skeleton curves obtained by numerical simulation are verified to be in good agreement with the experimental results. The numerical simulation outcomes regarding peak load and corresponding horizontal displacement maintain a relative error within 15 % compared to the experimental results.

Experimental study on the high water pressure erosion mechanism and its influence on the submarine shield tunnel concrete segments

This study investigated a high water pressure erosion mechanism and its influence on the mechanical performance deterioration of submarine shield tunnel concrete segments using a series of tests. First, a chloride ion pressure penetration test was conducted to reveal the impermeability performance and chloride ion permeability of the tunnel lining concrete. Then, given the environmental and mechanical characteristics of the lining segment structure of a submarine shield tunnel, a cofferdam-type electrochemically accelerated corrosion method was proposed to simulate the simultaneous application of unilateral water pressure and compression-bending loads on the segment. The effects of water pressure on the strain, deformation, crack propagation, and failure mode of the segment components were investigated. In addition, the damage caused by high water pressure on the segment components was explored using acoustic emission. This study lays the foundation for further research on the durability of shield tunnel structures under high water pressures.

Equivalent conversion investigation of environmental corrosion of suspenders in long-span suspension bridge

Purpose This paper aims to investigate the equivalent relationship between accelerated corrosion tests and real environmental spectrum of suspenders in long-span suspension bridge considering multiple factors action. Design/methodology/approach Based on Faraday's law, corrosion current was used as a measure of metal corrosion, and the equivalent conversion relationship between laboratory environment and real service environment was established. The equivalent conversion method for bridge structural steel had been determined under different temperature, humidity, pH value and NaCl concentration conditions. The compilation of environmental spectra for large span bridges considering multiple factors and the principle of equivalent conversion have been proposed. Findings Environmental factors, including temperature, humidity, pH value and NaCl concentration, have significant impact on the corrosion degree of suspension steel wires, and only considering these two factors for equivalent conversion cannot accurately reflect the true service environment of the bridge. The 33.8-h salt spray accelerated corrosion test using the standard conditions can be equivalent to one year of suspenders corrosion in a real service environment. Originality/value The equivalent accelerated corrosion method for steel wires proposed in this study can effectively predict the corrosion degree of the suspenders, which has been verified to be correct and can provide theoretical guidance for the development of corrosion test plans for steel wires and engineering technical basis for anti-corrosion control and calendar life research of suspension bridge suspenders.

Corrosion of steel rebars across UHPC joint interface under chloride attack

Corrosion of steel rebars across ultra-high-performance concrete (UHPC) joint interface under chloride attack is experimental investigated in the present study. The cases of concrete joint interface with normal concrete (NC) and high-performance concrete (HPC) are also investigated as the contrast. Twelve specimens are prepared and subjected to corrosion test. The corrosion potential and corrosion current density are measured to monitor the corrosion evolution of steel rebars. The effects of chloride concentration and cracking on the corrosion of steel rebar across the concrete joint interface are clarified. And the corrosion characteristic of steel rebars with a high corrosion loss are further investigated through the accelerated corrosion method. Results show that steel rebars across joint interface trend easily to be corroded for all the three cases with NC, HPC and UHPC. Corrosion of steel rebar across UHPC joint interface is just a little slower or slighter than the other cases across NC and HPC joint interface. The corrosion of steel rebars is highly centralized and localized at the joint interface for the case with UHPC, but relatively uniform without significant difference around the joint interface for the other cases with NC and HPC. Corrosion of steel rebars across concrete joint interface is sensitive to chloride concentration and interface cracking, especially for the case with UHPC.

Experimental Study on the Effects of Corrosion in Reinforced Concrete Incorporating Steel Fiber and Ultra-Fine Slag

Abstract: In this work, a thorough review of the literature was conducted with a primary focus on accelerated corrosion-induced corrosion. The report that follows compares different reinforced concrete mixtures following corrosion. By adjusting the transparent cover and reinforcement diameter, a simple reinforced concrete specimen, a specimen of reinforced concrete mixed with steel fiber, and a specimen of reinforced concrete mixed with steel fibre and ultra-fine slag were all produced. Using the accelerated corrosion method, the rate of induced corrosion, the flexural strength before and after corrosion, and the depth of corrosion penetration were compared.

Shear behavior of reinforced concrete beams subjected to accelerated non-uniform corrosion

In this paper, a modified accelerated corrosion method based on impressing current was adopted to generate non-uniform corrosion of stirrups in reinforced concrete (RC) beams. The shear performance of corroded RC beams was experimentally investigated, aiming to study the influence of stirrup corrosion induced by two different accelerated corrosion methods on the degradation of shear capacity of RC beams. Different corrosion degree of stirrups, corrosion of longitudinal steel bars, as well as shear span ratio were investigated. Results indicates that, the stirrups subjected to the modified accelerated corrosion method demonstrate a considerably higher circumferential and longitudinal non-uniformity, while the classic accelerated corrosion method induces a rather uniform corrosion. The non-uniformity of corrosion aggravates the propagation of both corrosion-induced and load-induced cracks, leading to the change of shear failure mode. The uniform corrosion induced by the classic accelerated corrosion method underestimates the degradation of shear capacity of RC beam, especially in the cases of corrosion degree no less than 15%. The corrosion of longitudinal steel bars mainly correlates to the decrease in the initial stiffness of RC beam, while little influence on the stiffness is observed with corroded stirrups.

Comparative experiment of steel bar corrosion at concrete construction joints

Introduction: Construction joint is common and even inevitable in most of the reinforcement concrete structures. This study was to assess the effect of construction joints on chloride-induced corrosion of reinforcing steel in concrete.Methods: Test parameters included two environmental conditions (salt solution immersion condition and cyclic wet-dry condition), two forms of construction joint (direct wet joint and roughened wet joint) and four types of steel bar (mild steel bar, ferritic stainless-steel bar, austenitic-ferritic stainless-steel bar and epoxy-coated steel bar). The corrosion test of 90 specimens was carried out by electrochemical accelerated corrosion method. The weight loss of each steel bar and steel bar section in specimens was measured. An influence coefficient (k_j) of construction joint on local weigh loss of steel bars was defined.Results: Except for epoxy-coated steel bars, the most severe corrosion of experimental steel bars in concrete specimens all occurred at the joints, while the corrosion in non-joint sections of steel bars was relatively uniform and less. The weight loss rate of specimens has the range of 1.18% to 15.73% with an average value of 6.22%. The average k_j of mild steel bars, S11203 stainless steel bars, and S23043 stainless steel bars are 1.38, 1.92, and 1.97, respectively. The average k_j of specimens in immersion condition and cyclic wet-dry condition are 1.44 and 2.07. The corrosion of epoxy-coated steel bars mainly occurred at the damage locations of epoxy coating, not mainly at the joints.Conclusion: Chloride-induced corrosion of steel bars at construction joints was always more severe than at non-joints, especially in cyclic wet-dry environments, even for stainless-steel bar, but epoxy-coated steel bars were excluded.

Non-uniform corrosion influences on mechanical performances of stainless-clad bimetallic steel bars

As a type of corrosion-resistant reinforcement, the stainless-clad bimetallic steel bar (SCBSB) has the advantages of low price and good mechanical properties, which causes them to be widely used in engineering structures. In the actual service process of the structure, the steel bar always corrodes first on the side close to the concrete cover. This type of non-uniform corrosion characteristic may lead to the mechanical properties of steel bars being very different from those with ideal uniform corrosion. Therefore, studying the degradation law of the mechanical properties of SCBSBs with non-uniform corrosion has important engineering value and research significance. In this study, the non-uniform corrosion mechanism was described, and non-uniformly corroded SCBSB specimens at different corrosion degrees were obtained by the electrochemical accelerated corrosion method. Through tests and analyses, the mechanical properties and toughness degradation laws of the SCBSB with non-uniform corrosion were obtained. Models were proposed to predict the mechanical properties and toughness of SCBSBs with non-uniform corrosion at any corrosion degree. In addition, through a finite element analysis, the mechanical property degradation laws of SCBSBs with three corrosion forms were analyzed. According to the experimental results, it was suggested that the corrosion degree of SCBSBs should be controlled within 14.39% to meet engineering requirements. The resistances of reinforced concrete beam with different corroded degrees SCBSBs were discussed to clarify the effect of corrosion type on durability of reinforced concrete members.

Experimental study on the shear behavior of friction connections with corrosion damage

Corrosion effects on the shear behavior of friction connections are experimentally investigated in this paper. Based on ultrasonic technique, double lap friction connections were firstly assembled and accurate preloads were applied on high-strength bolts. Electrochemical accelerated corrosion method was employed to achieve four corrosion levels of specimens. Tensile test was then conducted on the corroded specimens and a finite element model was also established to make a comparison with test results. The study shows that net cross-section failure occurred for all the specimens and no obvious reduction of bearing capacity was found for corroded connections within 10% weight loss. Two slippages occurred during loading and finite element analysis shows that the second slip displacement is caused by slippage between washer and bolt head/nut. For friction connections with four corrosion levels, slip factors firstly increased and then gradually decreased with increase of the corrosion degree, and a prediction model of frictional resistance of the friction connection was proposed. Contact analysis of interfaces between plates accounts for the distribution of corrosion damage on the inner plates. Load-displacement curves obtained from finite element model agree well with test results. Corrosion effects on the bearing capacity of the friction connections were analyzed as ultimate load increases when slip factor or bolt preload increases.

Evaluation of corrosion morphology on mechanical properties of reinforcing steel bars using numerical simulation and simplified analytical model

Corrosion of steel bars is the main issue affecting the durability of reinforced concrete structures. To obtain corroded steels with different target corrosion degree, an accelerated corrosion method was used. Then, the surface morphology was quantified by a three-dimensional scanning method. On the basis of 3D scanning, a numerical model was constructed and the finite element method was used to digitally analyse the mechanical behaviours of corroded bars. The reliability of numerical method was validated by comparing the simulated and test results. To better characterise the deformation behaviour of corroded steels, a simplified analytical model based on several major parameters was established. Finally, the theoretical range of the degraded ultimate strain was specified based on the cross-sectional parameters.

Macro-strain based deflection and neutral axis position monitoring of reinforced concrete beams during corrosion

This article proposes a new technique of monitoring neutral axis positions and deflection of Reinforced Concrete (RC) beam during corrosion of steel reinforcement using macro-strain measurements of distributed long-gauge sensors. A different group of distributed long-gauge Packaged Carbon Fiber Line (PCFL) sensors with self-compensation and effective packaging system is installed on the compression and tension fibers of the concrete surface and steel reinforcements of RC beam to verify the proposed method experimentally. An accelerated corrosion method utilizing a salt solution and the constant current was used to achieve the required corrosion levels. The estimated deflection measured by the developed method is compared with the results using Linear Variable Displacement Transducer (LVDTs). It has been demonstrated that long-gauge PCFL sensors could provide the same accuracy. The distributed measured strains were utilized to evaluate the deterioration of the structure’s health with the advance of corrosion. Based on corrosion monitoring experimental results, it can be confirmed that using distributed PCFL sensors mounted on steel reinforcements or concrete surface, the locations and progress of the damage with corrosion time can be detected effectively. The maximum error in the estimated deflection from PCFL sensors mounted on the concrete surface compared to the LVDTs before the onset and after 24 h of accelerated corrosion was 0.5% and 2.5%, respectively.

Corrosion characteristics of defective reinforced concrete

In order to further understand the corrosion mechanism of reinforcement and simulate the natural corrosion phenomenon, we use X-ray computed tomography (XCT) to nondestructively trace and analyze the corrosion process of the specimens containing the initial defect in protective layer. We compare three-dimensional corrosion morphology and damage of specimens containing interface, middle and surface defects under two accelerated corrosion experiments: the applied current experiment and the wet-dry cycles (W/D) experiment.The results show that W/D tends to produce spatially randomly distributed large pits, while energization produces uniformly distributed tiny pits. W/D corrosion produces generally larger crack widths at similar actual corrosion degree than those with energized accelerated corrosion, which is closer to the natural corrosion. The effects of different defect locations and accelerated corrosion methods on the accumulation of interfacial corrosion products are not obvious, but the cover cracking is obviously related to the defect location, the closer the defect is to the outside of the specimen, the more likely it leads to the cracking of specimen.