Accelerated Corrosion Technique Research Articles

Experimental investigation into corrosion effect on buckling and low-cycle fatigue performance of high-strength steel bars

The reinforcement in marine RC structures will inevitably be corroded under long-time erosion of chloride ions, which will weaken steel mechanical properties and then structural seismic resistance. The new metallurgical technology is adopted for manufacturing high-strength steel bars (HSSB), but that may affect the corrosion resistance of steel bars at the same time. This paper experimentally investigates the effects of corrosion on monotonic and low-cycle fatigue properties of HSSB HTRB600 and normal strength steel bars (NSB) HRB400E. The HRB400E and HTRB600 steel bars were corroded to different corrosion rates by electrochemical accelerated corrosion technique. The monotonic tensile and compressive, as well as low-cycle fatigue tests of corroded steel bars were conducted to investigate the effects of corrosion on steel mechanical properties, of which corrosion levels (0–20% target corrosion mass loss), slenderness ratios (L/D=6, 8, 10, 12) and strain amplitudes (2%, 4%) are considered. Test results show that, the corrosion morphology of steel bars under electrochemical accelerated corrosion is basically consistent with that observed under natural corrosion. Compared with uncorroded HRB400E and HTRB600 steel bars, 20% corrosion mass loss leads to 38% and 35% decrease in tensile strength, as well as 33% and 28% reduction in buckling stress, respectively. The HTRB600 steel bars present slightly superior monotonic tensile and compressive corrosion resistance than HRB400E steel bars. Corrosion obviously decreases the low-cycle fatigue (LCF) life of steel bars, resulting in reductions of 44% and 36% in LCF life at 20% corrosion mass loss for HTRB600 and HRB400E steel with a L/D of 6, respectively. Moreover, the HTRB600 steel bars present more significant corrosion degradation in total hysteretic dissipated energy, compared with HRB400E steel bars. The combined effect of corrosion and inelastic buckling further exacerbates the deterioration of LCF performance of steel bars. The corresponding deterioration models are proposed to determine the LCF life and energy dissipation capacity of corroded steel bars.

Accelerated Electromigration Approach to Evaluate Chloride-Induced Corrosion of Steel Rebar Embedded in Concrete

Two distinct binary blended concrete mixes were prepared for the study. The first mix involved a cement replacement of 50% slag, denoted as SL. The second mix incorporated a cement replacement of 20% fly ash, referred to as FA. No chlorides were added during the preparation of these concrete specimens. To accelerate chloride transport, electromigration was employed by placing specimens with varying reservoir lengths (ranging from 2.5 cm to 17.5 cm) on their top surfaces. These reservoirs were subsequently filled with a 10% NaCl solution. In this paper, corrosion propagation was monitored over a period of approximately 650 days using electrochemical measurements such as open circuit potential, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS). The evolution of rebar potential, polarization resistance, solution resistance, and corrosion current were analyzed to understand the corrosion behavior. This paper focuses on how the length of the solution reservoirs influences the corrosion-related parameters such as polarization resistance, solution resistance, rebar potential, and corrosion current. During the monitored propagation period, the corrosion current values (last 7 sets of readings) exhibited higher magnitudes for the embedded rebars in specimens made with SL mix in comparison to those made with FA mix. Corrosion current measurements likewise showed an increasing trend as the reservoir lengths increased. None of the specimens had any visible cracks or corroded products that could reach the concrete surface throughout the monitored period. The experimental results provide insights into the corrosion mechanisms and the effectiveness of accelerated corrosion techniques in simulating real-life conditions.

Experimental and analytical investigation on the use of NSM–BFRP and NSM–GFRP bars in strengthening corrosion–damaged RC slabs

This paper presents the results of an experimental and analytical study on the flexural behavior of corrosion–damaged reinforced concrete (RC) slabs strengthened with different near–surface mounted fiber–reinforced polymer (NSM–FRP) bars. An accelerated corrosion technique was used to induce corrosion in the steel reinforcing bars of the tested slabs. The investigated parameters comprised the number of NSM–FRP bars (two and four bars), the type of the NSM–FRP reinforcement (basalt B and glass G bars), and the mass loss in the steel rebars due to corrosion (10 and 20%). The yielding and ultimate capacity of the strengthened slabs was not only restored but surpassed those of the virgin control slab. Slabs strengthened with two and four NSM–BFRP bars showed 32–42% increase in their yielding load and 45–50% in their ultimate loads, respectively, as compared to the unstrengthened corroded slab. Similarly, the strengthened slabs showed 5–50% increase in their ductility index as compared to the virgin slab. The strengthened slabs failed due to the yielding of the steel reinforcing bars followed by compression concrete crushing. ACI–440 formulations reasonably predicted the performance of the strengthened slabs with conservative capacities when ACI strain limit of 0.7 εfu was considered.

Behavior and Performance of Reinforced Concrete Columns Subjected to Accelerated Corrosion

Steel reinforcement corrosion in concrete structures such as bridges, industrial plants, marine structures, and coastal buildings is a growing concern due to its impact on cost, safety, and serviceability. Corrosion leads to spalling, cracking, and reduced reinforcement diameter, which can compromise structural integrity. This study examines the behavior of concrete columns with corroded reinforcement in two phases. In the first phase, 72 columns of 150 × 150 mm cross-sectional dimensions and 300 mm length were cast and subjected to an accelerated corrosion technique. The study examined variables such as concrete cover, concrete strength, and corrosion exposure. The second phase involved studying the axial behavior of corroded columns concerning the effect of column length. Column specimens of 150 × 150 mm cross-sectional dimensions and lengths of 500 mm, 700 mm, and 900 mm were cast, corroded, and tested under axial compressive load. The study revealed that a 30 mm concrete cover offers 10% more protection against corrosion than a 20 mm cover. Continuous exposure to a corrosive environment reduces the load-carrying capacity by 50%, while columns with 28 MPa concrete strength can carry 4% more load. Longer columns are more susceptible to corrosion, leading to a significant reduction in load-carrying capacity and concrete cover damage. Therefore, maintaining adequate concrete cover, strength, and regular inspections are essential to address steel reinforcement corrosion and preserve structural integrity.

Corrosion Resistant Coating from Nano Printed Circuit Board Powder for the Reinforced Concrete Structures

Corrosion in steel leads to the deterioration of reinforced concrete structures due to chemical reactions between steel and its surrounding atmosphere. In this paper, a novel anticorrosive powder was derived from the waste Printed Circuit Board (PCB) and manually coated on the steel rebar of the reinforced concrete specimen. The corrosion-resistant efficiency of the developed nano PCB-coating on the steel bars was studied by polarization, electrochemical impedance spectroscopy, and accelerated corrosion technique. Also, the applicability of the nano PCB-coated rebar as reinforcement in the concrete environment was investigated. From the results, it was observed that the nano PCB-coated specimens exhibited 3.5 times reduced rate of corrosion and lost only 46.15% strength and 52.5% diameter under the accelerated rate of 6 V after 48 hours. The presence of nano PCB powder improved the corrosion-resistant behaviour of the steel rebar by 1.65 times of the noncoated specimen. Also, the nano PCB-coating reduced the loss in residual yield strength of the corroded steel rebar by 32% lesser than the noncoated specimens and exhibited similar corrosion-resistant properties as that of the existing zinc coating. In addition to the corrosion resistance, the nano PCB-coated steel rebar exhibited almost similar adhesion with concrete as that of the commercial zinc coating which is 7% lower than uncoated steel rebars. It was inferred from this research work that the proposed anticorrosive coating prepared from the waste nano PCB powder showed better corrosion-resistant behaviour and reduced the overall cost of coating by 42%, which ensures economy and serviceability.

Investigation of the effect of boron inhibitor on reinforced concrete by using the accelerated corrosion technique

Investigation of the effect of boron inhibitor on reinforced concrete by using the accelerated corrosion technique

Corrosion effects on axial compressive behavior of steel strapping tensioning technique-confined concrete

This paper presents an experimental study on effect of corrosion on durability performance of circular Steel Strapping Tensioning Technique (SSTT)-confined concrete tested under uniaxial compression. A total of 13 specimens, including 11 confined specimens and 2 plain specimens were tested in this study. The main parameters were prestressing level and corrosion protection. Corrosion was simulated through impressed current accelerated corrosion technique. The experimental results indicated that influence of corrosion was insignificant on peak strength and slight reduction in deformation ability to corroded circular SSTT-confined concrete under low corrosion severity. It was observed that Zn-Al-Cd ingot and long-oil alkyd paint coating shows good protection ability, while 6061 aluminum alloy and 99.9% pure magnesium is not suitable to be used as corrosion protection system. Based on regression analysis, prediction models for peak stress and peak strain for circular corroded SSTT-confined concrete were proposed.

Development of corrosion resistance of reinforcement steel bars with nano-silver coatings

The aims of this study are to examine the effect of metallic coatings on reinforcement from the perspective of the durability properties of concrete structures. Also, consider the importance of laboratory production of cover while investigating how it can be applied to steel. In this research, to increase the corrosion resistance of the structural steel, the reinforcements were coated with thin films with a system called thermionic vacuum arc (TVA). As a result of recent studies, it has been observed that such thin films protect the reinforcement from corrosion. In this study, the effect of coated reinforcement on corrosion, which is one of the most important structural defects, was investigated. The applied coatings are nano-sized and protect the structural steel against corrosion reactions occurring on the surface. Moreover, these coatings increase the adherence between concrete and reinforcement. Specifically, for this study, silver (Ag) was used as a coating component. After the coating process was completed, the reinforcements were placed in cylindrical concrete samples and their resistance to corrosion was measured with the help of the accelerated corrosion technique. The results show that the rebars coated with the TVA system was prolonged the damage occurrence time (first crack) and diminished the corrosion reactions that occurred on the reinforcement surface.

Assessment of the Corrosion of Steel Embedded in an Alkali-Activated Hybrid Concrete Exposed to Chlorides.

Hybrid alkali-activated cements (HAACs), also known as cements with high percentages of alkali-activated supplementary materials, are alternative cements that combine the advantages of ordinary Portland cement (OPC) and alkali-activated systems. These cements are composed of a minimum of 70% precursor material and a maximum of 30% OPC mixed with an alkaline activator. This article evaluates the corrosion performance of reinforced HAAC concrete based on fly ash (FA) under exposure to chlorides (FA/OPC, 80/20). Its performance is compared with that of a binary alkali-activated cement (AAC) based on FA and granulated blast furnace slag (GBFS) (FA/GBFS, 80/20). The tests performed on the concrete matrix correspond to the compressive strength and permeability to chloride ions. Using accelerated corrosion techniques (impressed voltage) and electrochemical tests after immersion in 3.5% NaCl, the progress of the corrosive process in the reinforcing steel is evaluated. The FA/OPC exhibit a better corrosion performance than the FA/GBFS concrete. At the end of the exposure to chlorides, the FA/OPC hybrid concrete presents the best performance, with a 49% lower corrosion rate than that of the FA/GBFS. Note that according to the polarization curves, the values of the proportionality constant B in the alkaline-activated concretes differ from the values recommended for concrete based on OPC.

Effect of Corrosion on Bond Strength of Tension Lap-Splices

This study aimed to investigate the effect of corrosion on the bond strength of tension lap splices in reinforced concrete beams. The test variables were the corrosion level (0%, 2.5% and 5.0%) and the concrete cover to bar diameter (c/d) ratio (c/d=1.5, 2.0, and 2.67). The observed failure mode was splitting of the concrete cover on the tension side. An accelerated corrosion technique was used to corrode the reinforcing lap-spliced bars in a reasonable time frame. Corrosion did not affect failure mode but caused a reduction in the ultimate strength and deflection at failure. The bond strength was reduced by 15% to 26% at 2.5% corrosion level and by 21% to 38% at 5% corrosion level depending on the c/d ratio. A model was proposed to predict the bond strength of corroded tension lap-splices in concrete. The model results correlated well with the measured bond strength.

Bond behavior between corroded steel bar and concrete under reciprocating loading history of beam type specimens

The bond between steel bars and concrete can be deteriorated by corrosion. A series of beam specimens with initial cracks were cast to study the effects of corrosion on bond behavior. The current-induced accelerated corrosion technique was used to reach four levels of corrosion (0%, 3%, 5% and 7%), and different amplitudes of reciprocating load (0%, 10%, 20% and 30% of ultimate load) were applied on the specimens. Finally, the flexural-bond test was carried out on specimens to obtain the bond strength and bond stress-slip relationships. The results show that the bond strength decreases with the increase in corrosion rate, and deterioration under the coupling condition of reciprocating load and corrosion is more significant, which can be reduced over 50%. And the higher the corrosion level, the faster the slip increases. In addition, the bond stress-slip relationship and the bond strength degradation model are proposed, which can be used to predict the changes of bond behavior under corresponding working conditions.

Temperature-dependent properties of corroded super ductile TMT steel bars

Super ductile TMT reinforcing steel bars are commonly used these days for RC constructions, given their excellent thermal properties. SD TMT rebars are superior due to their distinct cross-sectional phase distribution (CSPD) of martensite, bainite, and pearlite. This paper investigates the influence of the superimposition of corrosion-induced damage by the exposure to elevated temperatures on properties of reinforcing steel simulating corroded structural members exposed to an accidental fire. The experimental program involved exposing bare bars to accelerated corrosion to achieve desired corrosion levels in terms of mass loss using the impressed current accelerated corrosion technique to a precision level of ± 1%. Subsequently, the identical specimens were heated to 250 °C, 550 °C, 800 °C, and 950 °C and allowed to achieve a steady-state at that temperature before being cooled down to ambient temperatures in the furnace itself and tested in tension to failure. A detailed analysis of the effect of various combinations of corrosion-induced mass loss and elevated temperatures on ductility characteristics of reinforcing steel using various prevalent methods in the available literature is presented. The results indicate a notable reduction in reinforcing steel's critical mechanical properties due to the superimposition of the two phenomena.

Investigation of the effects of multiple and multi-directional reinforcement on corrosion-induced concrete cracking pattern

Reinforced concrete (RC) structures are widely used, yet prone to damage induced by reinforcement corrosion which causes susceptibility of concrete spalling and eventually a reduced serviceable life. The visual inspection has been performed usually for structural assessment, but this does not account for the local interactions between rebars. Consequently, detailed scrutiny is required to consider the effects of various parameters on the initiation and propagation of corrosion-induced cracking. This experimental study considers the effect of multiple and multidirectional rebars on the development of corrosion cracking. Additionally, the effect of the location of corrosion and the change in order of corrosion occurrence is investigated in this research. For this purpose, reinforced concrete panels with unidirectional and multidirectional rebar arrangements and varying cover depth are tested using an accelerated corrosion technique. The results show a significant role of confinement in controlling the widths of cracks provided by both reinforcement arrangements. Moreover, the effect of boundary conditions along with increased confining pressure alters the generation of cracks in a unidirectional reinforcement arrangement. In the absence of enough surrounding concrete, cracks along non-corroding rebars can also form because of the expansion of adjacent corroding rebars. The inclusion of multidirectional reinforcement alters the crack direction and causes cracking along non-corroding rebars. Further, previously generated cracks may close considerably by the pressure from adjacent rebar corrosion. This study also facilitates the comprehension of the impact of influencing factors affecting corrosion cracking in real structures.

Effect of Different Strengthening Techniques on the Structural Behaviour of Continuous Two-Way Slabs with Partially Corroded Reinforcement at Internal Support

This research studies the combined effects of partial corrosion of the negative reinforcement in two-way continuous slabs (two spans) with a construction joint at the internal support and investigates the efficiency of the proposed strengthening methods to overcome these effects. The partial corrosion in reinforcement comes from exposure to the corrosive outdoor environment due to an unplanned stoppage in concrete pouring for a long-time which left part of the negative reinforcement without protection. The construction joint formed at the internal support after resume the concrete pouring later. Three types of strengthening are proposed to overcome those effects. The study adopted an accelerated corrosion technique which is running an electrical current in the steel bars partially immersed in a 5% salt solution (elect-chemical cell). The proposed strengthening was: NSM CFRP bars, CFRP strips, and steel plates. All applied to the top face in the tension zone at the internal support. Six two-way continuous (two spans) concrete slabs were cast (2200, 1000, and 100 mm). The strengthening was: four strips of CFRP had 50 mm width, four of 6 mm CFRP bars applied using the NSM technique, and four steel plate 50 mm width and 5 mm thickness. All the strengthening extended to the third of span length and was aligned with the slab continuity axis. The specimens were tested and the deflection, first positive and negative crack width, and failure mode were recorded. Numerical analysis and comparison with the experimental results were conducted to verify the numerical model. The study found that the construction joint and corrosion had a clear influence on the structural behavior of the slab. Those effects were on the ultimate load, deflection, and the negative cracks. The proposed treatments were highly effective and efficient in increasing the ultimate load, delay the appearance of cracks, and reduction of deflection under the load points.

Performance evaluation of reinforced concrete beams with corroded web reinforcement: Experimental and theoretical study

This study investigated the effect of corroded web reinforcement on the shear behavior of reinforced concrete (RC) beams. In this study, nine shear-critical RC beams were cast and tested. Six of these beams were corroded stirrups, while the remaining three beams were uncorroded stirrups serving as control samples. An accelerated corrosion technique was employed to corrode the stirrups in the beams. After the accelerated corrosion process, the beams were tested in three-point bending over a simply supported span. The shear span-to-depth ratio was kept constant at 3 for all beam specimens. The effects of the corrosion level, the type of steel stirrups (smooth or deformed), and the stirrup diameter were considered in the tests. The corrosion damage could easily be observed in the form of rust stains and corrosion cracks, which developed parallel to the stirrups. The beams with higher corrosion levels showed a reduction in their shear capacities. This reduction was more apparent in the beams with deformed steel stirrups. The shear capacities of the test beams were analyzed using a theoretical model that considers the effects of corrosion of the stirrups. The results of the analysis showed a good correlation between the experimental and theoretical shear strengths of the beam specimens.

Bond of naturally corroded, plain reinforcing bars in concrete

In the past, reinforced concrete structures were built utilising plain reinforcement bars. Currently, this construction method is seldom considered by codes and research; however, many heritage structures are still standing and in need of proper assessment. In particular, there is a lack of knowledge on the effect of corrosion on the bond between concrete and plain reinforcement bars. To address this gap, pullout tests were performed on reinforced concrete specimens sourced from a decommissioned bridge originally constructed in 1935. The specimens were naturally corroded, as the use of accelerated corrosion techniques in structural tests is still debated. A total of 156 pullout tests were conducted on specimens with varying thicknesses. The pullout force, active and passive slip, and corrosion levels were measured. The effect of corrosion on the bond strength, and the amount of visible damage owing to the presence of corrosion products, were influenced by the casting position of the reinforcing bars. The presence of stirrups influenced the post-peak behaviour, increased the residual bond strength, and helped maintain the bond strength in the presence of cracks and spalling damage. Additionally, current code provisions were found to provide conservative values for the peak bond stress of plain reinforcing bars.

Review on Effect of Corrosion on Flexure, Shear and Torsional Strength of Reinforced Concrete Beam

With the increase in demand for construction materials, man has improved a lot in the construction techniques of structures. Reinforced concrete beams are normally designed as under reinforced to provide ductile behavior such as the tensile moment of resistance. In coastal environment reinforcement corrosion is an obvious cause of deterioration of concrete structure, which affects the durability and service of reinforced concrete structure. Structural stability is majorly influenced by strength of concrete. Torsional strength is a measure of the shear strength of concrete, in other words it is a measure of a resistance against failure in twisting. The main aim of this study is to analyze the flexural, shear & torsional strength, experimentally; of corroded beams using Ordinary Portland cement. Accelerated corrosion technique was adopted to corrode the beam experimentally. We have used varying percentage of corrosion as 0%, 2.5%, 5% and 7.5%. Change in strength of RC beams is studied for varying percentage of corrosion. Beam specimens are prepared using M20 grade concrete for OPC. Beam specimens casted are tested in UTM for flexure and shear. Specially prepared loading setup is used for torsional strength test.

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.

Partially corroded reinforced concrete piers under axial compression and cyclic loading: An experimental study

Twelve reinforced concrete (RC) pier specimens were developed and partially corroded to simulate severe corrosion in splash and tidal zones. Six target corrosion levels were applied to rebars and stirrups using an electrochemical accelerated corrosion technique. Axial compression loading and cyclic loading tests were carried out with six specimens per group. The test results showed that mechanical parameters of pier specimens degraded with an increase in corrosion. The ultimate load, ductility factor, energy dissipation decreased by 29.96%, 9.26%, 67.44% for axial compression specimen with 15.82% rebar mass loss compared to those of intact specimen; for cyclic loading specimens, they decreased by 10.69%, 21.47%, 57.46% with 15.71% rebar mass loss, respectively. Comparative analysis showed that the difference for the degradation level of dimensionless parameters was not obvious between axial compression loading and cyclic loading tests. Findings also showed that for severely corroded specimens, the plastic hinge zone transferred from the bottom of RC piers to the splash and tidal zones. Although the extent of the degradation of the results between the published paper and this test shows significant variations; degradation of dimensionless energy dissipation was always the most serious one.

Effect of Plastering Layer on Corrosion Resistances of Reinforced Concrete Beams

Reinforced concrete structures are subjected to deterioration due to many factors such as corrosion of reinforcing steel. Ultimate strengths of structural elements can be greatly affected by these deteriorating factors. There are numerous methods and techniques used to protect these structural elements. The mortar layer (Plastering) is considered the first defense line against all the deteriorating factors. The main goal of this research is to investigate to what extent the plastering layer can protect reinforced concrete beams against corrosion. The aim of the experimental program is to study the effect of plastering layer on corrosion resistance of reinforced concrete beams. Four reinforced concrete beams (1002001100 mms) and four Lollypop specimens (cylinders 100200 mms) were tested and described as follows: • A beam and a lollypop specimen without any plastering layer (control). • A beam and a lollypop specimen with traditional plastering layer (cement + sand + water). • A beam and a lollypop specimen with modified plastering (traditional plastering + waterproof admixtures). • A beam and a lollypop specimen with painted and modified plastering layer (traditional plastering + waterproof admixtures + external waterproof paint). These eight specimens were subjected to corrosion using accelerated corrosion technique, after that the four beams were tested in flexure under three point load arrangement while the four lollypops were used to calculate the total mass loss due to accelerated corrosion. The test results were used to figure out the effect of plastering layer on corrosion resistance of RC beams.