Corrosion Characteristics and Corrosion Current Distribution of Steel Bar in Carbonated Concrete

2011 ◽  
Vol 239-242 ◽  
pp. 3371-3376 ◽  
Author(s):  
Yong Sheng Ji ◽  
Jian Li Shen ◽  
Lei Wang ◽  
Cong Yu Xu
Keyword(s):  
Current Distribution ◽  
Experimental Verification ◽  
Corrosion Current ◽  
General Assumption ◽  
Concrete Cover ◽  
Corrosion Mechanism ◽  
General Corrosion ◽  
Steel Bar ◽  
Corrosion Mechanisms ◽  
Macrocell Corrosion

The corrosion characteristics of steel bar in concrete are decided by the corrosion current distribution along the circumference of the steel bar. It is a general assumption that carbonation lead to a general corrosion on the rebar. However, the destruction of a large number of specimens indicated that before corrosion cracking, the carbonation-induced corrosion mainly distributes on the surface of the steel bar facing the concrete cover. This paper examined the corrosion mechanism from fundamental electrochemical principles and experimental verification. It was illustrated that the macrocell corrosion must co-exist with microcell corrosion, both macrocell and microcell corrosion mechanisms could play significant roles, and the total corrosion could be underestimated if each of two is overlooked.

scholarly journals Modelling of Corrosion-Induced Concrete Cover Cracking Due to Chloride Attacking

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1440
Author(s):  
Pei-Yuan Lun ◽  
Xiao-Gang Zhang ◽  
Ce Jiang ◽  
Yi-Fei Ma ◽  
Lei Fu
Keyword(s):  
Service Life ◽  
Corrosion Current ◽  
Practical Experience ◽  
Concrete Cover ◽  
Premature Failure ◽  
Rc Structures ◽  
Structural Capacity ◽  
Cover Cracking ◽  
Deterioration Process ◽  
Cracking Process

The premature failure of reinforced concrete (RC) structures is significantly affected by chloride-induced corrosion of reinforcing steel. Although researchers have achieved many outstanding results in the structural capacity of RC structures in the past few decades, the topic of service life has gradually attracted researchers’ attention. In this work, based on the stress intensity, two models are developed to predict the threshold expansive pressure, corrosion rate and cover cracking time of the corrosion-induced cracking process for RC structures. Specifically, in the proposed models, both the influence of initial defects and modified corrosion current density are taken into account. The results given by these models are in a good agreement with practical experience and laboratory studies, and the influence of each parameter on cover cracking is analyzed. In addition, considering the uncertainty existing in the deterioration process of RC structures, a methodology based on the third-moment method in regard to the stochastic process is proposed, which is able to evaluate the cracking risk of RC structures quantitatively and predict their service life. This method provides a good means to solve relevant problems and can prolong the service life of concrete infrastructures subjected to corrosion by applying timely inspection and repairs.

Electrochemical and Salt Spray Corrosion Behavior of Copper Alloy Contact Wires in Chloride Solution

2014 ◽  
Vol 789 ◽  
pp. 622-626
Author(s):  
Peng Chao Zhang ◽  
Jian Zhang ◽  
Jin Chuan Jie ◽  
Yuan Gao ◽  
Yong Dong ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Corrosion Test ◽  
Chloride Solution ◽  
Copper Alloys ◽  
Salt Spray ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Corrosion Mechanism ◽  
Salt Spray Corrosion ◽  
Surface Morphologies

The effect of different alloying elements on corrosion behavior of copper alloys was investigated using electrochemical corrosion and salt spray corrosion test in NaCl solution. Cu-Ag has the most stable corrosion current in the potentiostatic scanning test, exhibiting a better corrosion resistant performance. It can be analyzed from corrosion surface morphologies that Cu-Ag presents exfoliation corrosion mechanism while Cu-Sn shows crevice corrosion mechanism. Cu-Mg has a complex corrosion process caused by multiple corrosion mechanism. In the salt spray corrosion test, the corrosion degree of Cu-Ag is lighter than those of Cu-Sn and Cu-Mg after 24h test. Therefore, the Cu-Ag alloy exhibits the best corrosion resistance in chloride solution.

Evaluation on the Addition of Inhibitor and Surface Treatment to Corrosion Behavior of the Reinforced Steel Bar Embedded in Mortar Specimen

2017 ◽  
Vol 744 ◽  
pp. 114-120
Author(s):  
Kyung Man Moon ◽  
Sung Yul Lee ◽  
Jae Hyun Jeong ◽  
Myeong Hoon Lee
Keyword(s):  
Current Density ◽  
Test Specimen ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Corrosion Properties ◽  
Mortar Specimen ◽  
Steel Bar ◽  
Steel Bars ◽  
Reinforced Steel ◽  
One Year

In this study, seven types of mortar test specimens were manufactured with parameters, that is, the surface of the reinforced steel bar was treated with hot dip galvanizing (Zn) and the surface of the test specimen was coated with underwater paint, and four types of inhibitors (DAW, MCI, DCI, and Silcon) were added in mortars respectively. And, the seven types of mortar test specimens were immersed in seawater for 4 years. The corrosion properties of the reinforced steel bars embedded in mortar test specimens were investigated using electrochemical methods. The corrosion potentials of the test specimens with painting on the surface of the specimen and Zn coating on the surface of the steel bar exhibited the noblest and lowest values respectively after one year, however, after 4 years, the specimens of underwater painting and of addition of Silcon inhibitor indicated the noblest and lowest values of corrosion potentials respectively. Furthermore, the painting specimen exhibited the smallest values of corrosion probability as welll as of the corrosion current density, while, addition of MCI inhibitor showed the highest values of both corrosion probability and corrosion current density. Moreover, the painting specimen showed the smallest value of neutralization degree among all the specimens, and the largest value of neutralization degree was observed at the specimen of natural condition (no adding of inhibitor, no painting and no Zn coating). As a result, it is considered that the addition of inhibitors, coating with hot dip galvanizing (Zn), and painting on the surface have the effects not only to inhibit the neutralization degree but also to increase the corrosion resistance of the embedded steel bar.

scholarly journals Effect of Nitrite Inhibitor on the Macrocell Corrosion Behavior of Reinforcing Steel

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Zhonglu Cao ◽  
Makoto Hibino ◽  
Hiroki Goda
Keyword(s):  
Corrosion Behavior ◽  
Current Density ◽  
Polarization Resistance ◽  
Cement Mortar ◽  
Corrosion Current ◽  
Potential Difference ◽  
Reinforcing Steel ◽  
Macrocell Current ◽  
The Relationship ◽  
Macrocell Corrosion

The effect of nitrite ions on the macrocell corrosion behavior of reinforcing steel embedded in cement mortar was investigated by comparing and analyzing the macrocell corrosion current, macrocell polarization ratios, and slopes of anodic and cathodic steels. Based on the experimental results, the relationship between macrocell potential difference and macrocell current density was analyzed, and the mechanism of macrocell corrosion affected by nitrite ions was proposed. The results indicated that nitrite ions had significant impact on the macrocell polarization ratios of cathode and anode. The presence of nitrite could reduce the macrocell current by decreasing the macrocell potential difference and increasing the macrocell polarization resistance of the anode.

scholarly journals Instant performance verification after electrochemical chloride extraction by enhanced corrosion testing

2019 ◽  
Vol 289 ◽  
pp. 03009
Author(s):  
Ulrich Schneck
Keyword(s):  
Treatment Time ◽  
Performance Testing ◽  
Chloride Content ◽  
Corrosion Current ◽  
Concrete Cover ◽  
Chloride Ingress ◽  
Corrosion Activity ◽  
Multi Stage ◽  
Chloride Profile ◽  
Electrochemical Chloride Extraction

Electrochemical chloride extraction (ECE) is meant to re-establish the corrosion protection of concrete for the embedded reinforcement by removing chloride non-destructively and by enhancing the alkalinity of the rebar surrounding concrete. Both effects depend on various parameters, such as concrete cover, rebar spacing, chloride profile (especially if chloride ingress is deeper than the outside rebar layer) and concrete permeability. Often these parameters require long or multi-stage treatments, which basically can achieve any desired target level of chloride profile and impressed charge, but become a costly solution after a while. The acceptance criteria mentioned in CEN TS 14038-2 clause 8.6 refer to the achieved chloride content and to the amount of impressed charge, which are the conventional, easy measurable, but not direct parameters for evaluating the corrosion activity. A third parameter – the re-measurement of potentials for assessing (intended) low potential gradients and more positive average potentials – requires some weeks to months of depolarization and evaporation of water, before such a measurement can be applied successfully. A promising approach for an instant performance testing after an ECE treatment has been made on several occasions with follow-up measurements of electrolyte resistance, polarization resistance and corrosion current. Convincing changes towards significantly lower corrosion activity could be obtained (and compared to known classified values) – regardless of sometimes high residual chloride and very wet concrete. These data could be verified when re-assessed after some weeks, so enhanced corrosion measurements seem to be a useful tool for either establishing that the designed treatment time has been sufficient or to check on possible earlier termination of the treatment during a running ECE.

scholarly journals Effect of Sn Addition on Microstructure and Corrosion Behavior of As-Extruded Mg–5Zn–4Al Alloy

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2069 ◽  
Author(s):  
Jian Ding ◽  
Xin Liu ◽  
Yujiang Wang ◽  
Wei Huang ◽  
Bo Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Corrosion Behavior ◽  
Photoelectron Spectroscopy ◽  
Corrosion Current ◽  
Electrochemical Measurements ◽  
Corrosion Mechanism ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Average Grain Size

The effect of Sn addition on the microstructure and corrosion behavior of extruded Mg–5Zn–4Al–xSn (0, 0.5, 1, 2, and 3 wt %) alloys was investigated by optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical measurements, and immersion tests. Microstructural results showed that the average grain size decreased to some degree and the amount of precipitates increased with the increasing amount of Sn. The extruded Mg–5Zn–4Al–xSn alloy mainly consisted of α-Mg, Mg32(Al,Zn)49, and Mg2Sn phases as the content of Sn was above 1 wt %. Electrochemical measurements indicated that the extruded Mg–5Zn–4Al–1Sn (ZAT541) alloy presented the best corrosion performances, with corrosion potential (Ecorr) and corrosion current density (Icorr) values of −1.3309 V and 6.707 × 10−6 A·cm−2, respectively. Furthermore, the corrosion mechanism of Sn is discussed in detail.

A DFT study on corrosion mechanism of steel bar under water-oxygen interaction

2020 ◽  
Vol 171 ◽  
pp. 109265 ◽  
Author(s):  
Zheng Chen ◽  
Yumei Nong ◽  
Jianhua Chen ◽  
Ye Chen ◽  
Bo Yu
Keyword(s):  
Dft Study ◽  
Corrosion Mechanism ◽  
Water Oxygen ◽  
Steel Bar ◽  
Oxygen Interaction

scholarly journals Effects of Variations in Salt-Spray Conditions on the Corrosion Mechanisms of an AE44 Magnesium Alloy

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
Holly J. Martin ◽  
M. F. Horstemeyer ◽  
Paul T. Wang
Keyword(s):  
Galvanic Corrosion ◽  
Salt Spray ◽  
Chloride Ions ◽  
General Corrosion ◽  
Multiple Exposure ◽  
Test Conditions ◽  
Lightweight Alloys ◽  
Pit Nucleation ◽  
Corrosion Mechanisms ◽  
By Products

The understanding of how corrosion affects magnesium alloys is of utmost importance as the automotive and aerospace industries have become interested in the use of these lightweight alloys. However, the standardized salt-spray test does not produce adequate corrosion results when compared with field data, due to the lack of multiple exposure environments. This research explored four test combinations through three sets of cycles to determine how the corrosion mechanisms of pitting, intergranular corrosion, and general corrosion were affected by the environment. Of the four test combinations, Humidity-Drying was the least corrosive, while the most corrosive test condition was Salt Spray-Humidity-Drying. The differences in corrosivity of the test conditions are due to the various reactions needed to cause corrosion, including the presence of chloride ions to cause pit nucleation, the presence of humidity to cause galvanic corrosion, and the drying phase which trapped chloride ions beneath the corrosion by-products.

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