Non-uniform corrosion of steel in mortar induced by impressed current method: An experimental and numerical investigation

2018 ◽  
Vol 183 ◽  
pp. 429-438 ◽  
Author(s):  
Chuanqing Fu ◽  
Nanguo Jin ◽  
Hailong Ye ◽  
Jiamin Liu ◽  
Xianyu Jin
Keyword(s):  
Numerical Investigation ◽  
Current Method ◽  
Uniform Corrosion ◽  
Impressed Current ◽  
Corrosion Of Steel

scholarly journals Effect of Cathodic Protection on Reinforced Concrete with Fly Ash Using Electrochemical Noise

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2438
Author(s):  
Jorge García-Contreras ◽  
Citlalli Gaona-Tiburcio ◽  
Irene López-Cazares ◽  
Guillermo Sanchéz-Díaz ◽  
Juan Carlos Ibarra Castillo ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Fly Ash ◽  
Cathodic Protection ◽  
Electrochemical Noise ◽  
Uniform Corrosion ◽  
Concrete Mixtures ◽  
Impressed Current ◽  
The Difference ◽  
Passive Current ◽  
Corrosion Of Steel

Corrosion of steel reinforcement is the major factor that limits the durability and serviceability performance of reinforced concrete structures. Impressed current cathodic protection (ICCP) is a widely used method to protect steel reinforcements against corrosion. This research aimed to study the effect of cathodic protection on reinforced concrete with fly ash using electrochemical noise (EN). Two types of reinforced concrete mixtures were manufactured; 100% Ordinary Portland Cement (OCP) and replacing 15% of cement using fly ash (OCPFA). The specimens were under-designed protected conditions (−1000 ≤ E ≤ −850 mV vs. Ag/AgCl) and cathodic overprotection (E < −1000 mV vs. Ag/AgCl) by impressed current, and specimens concrete were immersed in a 3.5 wt.% sodium chloride (NaCl) Solution. The analysis of electrochemical noise-time series showed that the mixtures microstructure influenced the corrosion process. Transients of uniform corrosion were observed in the specimens elaborated with (OPC), unlike those elaborated with (OPCFA). This phenomenon marked the difference in the concrete matrix’s hydration products, preventing Cl− ions flow and showing passive current and potential transients in most specimens.

Effects of Fatigue Damage on Bond Behavior between Corroded Rebar and Concrete

2019 ◽  
Author(s):  
Yunpeng Zhang ◽  
Weiping Zhang ◽  
You Hu
Keyword(s):  
Bond Strength ◽  
Fatigue Damage ◽  
Current Method ◽  
Fatigue Loading ◽  
Repeated Loading ◽  
Relative Slip ◽  
Pull Out ◽  
Bond Degradation ◽  
Impressed Current ◽  
Different Levels

Bond degradation due to rebar corrosion and fatigue loading may affect the serviceability and even safety of reinforced concrete (RC) bridges. 15 specimens confined with stirrups were cast for eccentric pull-out tests, and 12 of them were corroded with the target mass loss of 0.03 by the impressed current method. Monotonic pull-out tests were conducted on three corroded and three uncorroded specimens. Wavy descending branch was found in bond stress-slip test curves of uncorroded specimens attributed to stirrup confinement, however it disappeared in those curves of the corroded specimens due to the corrosion loss of rebar transverse ribs. Based on the tested monotonic bond strength, the other nine corroded specimens of different fatigue damages were obtained through repeated loading with different levels and cycles before undergoing monotonic pull-out tests. It is observed that the relative slip increases with a gradually decreasing rate as the loading cycles increase. The monotonic tests of specimens with fatigue damage show that the bond strength increases to a certain value and then decreases with the increase of fatigue loading cycles. Moreover, the higher the loading level is, the fewer cycles are needed to reach the maximum bond strength. In addition, the peak slip corresponding to bond strength decreases with the increase of fatigue loading cycles.

Experiment Study on Degradation Laws of Sulfuric Acid Corrosion Reinforcements

2018 ◽  
Vol 878 ◽  
pp. 23-27 ◽  
Author(s):  
Ming Qiang Lin ◽  
Feng Juan Dai ◽  
Jia Tao Li
Keyword(s):  
Sulfuric Acid ◽  
Acid Corrosion ◽  
Constitutive Models ◽  
Corrosion Damage ◽  
Uniform Corrosion ◽  
Steel Bars ◽  
Relationship Model ◽  
Strain Relationship ◽  
Sulfuric Acid Corrosion ◽  
Corrosion Of Steel

The corrosion of concrete structures is serious in sulfuric acid environments. Corrosion damage of reinforcements caused sulfuric acid corrosion is very serious. The rapid experiments of sulfuric acid corrosion steel bars were carried out, and the apparent morphology and mechanical properties of sulfuric acid corrosion steel bars were studied. The results show that the corrosion of steel bars is uniform corrosion. With the increase of corrosion rate, the yield platforms and the yield strengths and ultimate strengths are reduced. Based on the experimental datas, the relationship models between yield strengths and ultimate strengths and corrosion rates were obtained. The constitutive models of corrosion steel bars were established. The stress - strain relationship model is in good agreement with the experimental data.

scholarly journals Concrete Protective Layer Cracking Caused by Non-Uniform Corrosion of Reinforcements

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4245 ◽  
Author(s):  
Lu Zhang ◽  
Ditao Niu ◽  
Bo Wen ◽  
Daming Luo
Keyword(s):  
Radial Displacement ◽  
Concrete Strength ◽  
Protective Layer ◽  
Concrete Cover ◽  
Uniform Corrosion ◽  
Reinforcement Corrosion ◽  
Concrete Cracking ◽  
Principal Tensile Stress ◽  
Cover Thickness ◽  
Corrosion Of Steel

The volume expansion of reinforcement corrosion products resulting from the corrosion of steel reinforcement embedded into concrete causes the concrete’s protective layer to crack or spall, reducing the durability of the concrete structure. Thus, it is necessary to analyze concrete cracking caused by reinforcement corrosion. This study focused on the occurrence of non-uniform reinforcement corrosion in a natural environment. The characteristics of the rust layer were used to deduce the unequal radial displacement distribution function of concrete around both angular and non-angular bars. Additionally, the relationship between the corrosion ratio and the radial displacement of the concrete around the bar was established quantitatively. Concrete cracking due to the non-uniform corrosion of reinforcements was simulated using steel bars embedded in concrete that were of uneven displacement because of rust expansion. The distribution of the principal tensile stress around the bar was examined. A formula for calculating the critical radial displacement at the point when cracking began was obtained and used to predict the corrosion ratio of the concrete cover. The determined analytical corrosion ratio agreed well with the test result. The effect factor analysis based on the finite element method indicated that increasing the concrete strength and concrete cover thickness delays concrete cracking and that the adjacent rebar causes the stress superposition phenomenon.

Cathodic Protection of Grounding Grids

2018 ◽  
pp. 248-286
Keyword(s):  
Cathodic Protection ◽  
Galvanic Corrosion ◽  
Steel Corrosion ◽  
Uniform Corrosion ◽  
Grounding System ◽  
Grounding Grid ◽  
Grounding Grids ◽  
Corrosion Pitting ◽  
Impressed Current ◽  
Cathodic Protection System

This chapter contains the corrosion theory of grounding electrodes and basic electrochemistry in corrosion reactions. It contains also the forms of substation grounding grid corrosion (uniform corrosion, pitting corrosion, galvanic corrosion, microbial influenced corrosion), survey on corrosion rate of substation grounding grid, copper and steel corrosion rates, corrosion protection methods (coating, cathodic protection [CP]). The chapter contains also the methods of applying cathodic protection in grounding grids, anode selection, anode spacing, and impressed current in the grounding grid cathodic protection. Finally it contains the required information for design grounding system cathodic protection and sacrificial anode (galvanic) cathodic protection system design steps.

scholarly journals Indirect Galvanostatic Pulse in Wenner Configuration: Numerical Insights into Its Physical Aspect and Its Ability to Locate Highly Corroding Areas in Macrocell Corrosion of Steel in Concrete

2020 ◽  
Vol 1 (3) ◽  
pp. 373-407
Author(s):  
Romain Rodrigues ◽  
Stéphane Gaboreau ◽  
Julien Gance ◽  
Ioannis Ignatiadis ◽  
Stéphanie Betelu
Keyword(s):  
Steady State ◽  
Polarization Resistance ◽  
Short Circuit ◽  
Potential Difference ◽  
Physical Aspect ◽  
Uniform Corrosion ◽  
Rc Structures ◽  
Ohmic Drop ◽  
Problematic Issue ◽  
Corrosion Of Steel

The use of indirect electrical techniques is gaining interest for monitoring the corrosion of steel in concrete as they do not require any connection to the rebar. In this paper, we provide insights into the physical aspects of the indirect galvanostatic pulse (GP) method in the Wenner configuration. Considering uniform corrosion, the instantaneous ohmic drop is decreased due to the presence of the rebar, which acts as a short-circuit. However, we observed that this phenomenon is independent of the electrochemical parameters of the Butler–Volmer equation. They are, however, responsible for the nonlinear decrease of the current that polarizes the rebar over time, especially for a passive rebar due to its high polarization resistance. This evolution of the resulting potential difference with time is explained by the increase of the potential difference related to concrete resistance and the global decrease of the potential difference related to the polarization resistance of the rebar. The indirect GP technique is then fundamentally different than the conventional one in three-electrode configuration, as here the steady-state potential is not only representative of polarization resistance but also of concrete resistance. Considering non-uniform corrosion, the presence of a small anodic area disturbs the current distribution in the material. This is essentially due to the different capability of anodic and cathodic areas to consume the impressed current, resulting in slowing down the evolution of the transient potential as compared to uniform corrosion. Hence, highly corroding areas have a greater effect on the transient potential than on the steady-state one. The use of this temporal evolution is thus recommended to qualitatively detect anodic areas. For the estimation of their length and position, which is one of the main current problematic issue when performing any measurement on reinforced concrete (RC) structures with conventional techniques, we suggest adjusting the probe spacing to modulate the sensitivity of the technique.

scholarly journals The effects of anode distance and corrosion activity on current distribution for ICCP systems

2019 ◽  
Vol 289 ◽  
pp. 03001
Author(s):  
Shamir Bhuiyan ◽  
David Law ◽  
Liam Ward ◽  
Justin Saliba
Keyword(s):  
Current Distribution ◽  
Steel Reinforcement ◽  
Cathodic Current ◽  
Potential Sweep ◽  
Factors Affecting ◽  
Uniform Current ◽  
Different Depths ◽  
Impressed Current ◽  
Corrosion Of Steel ◽  
Impressed Current Cathodic Protection

One of the most effective techniques to mitigate corrosion of steel reinforcement in concrete is impressed current cathodic protection (ICCP). This technique has been widely used for several decades; however, there is limited research systematically studying the various factors affecting the distribution of cathodic current over the area of steel reinforcement. Understanding how current is distributed in an ICCP system is crucial for its design to ensure that all areas of steel are sufficiently protected, and overprotection of certain areas is avoided. In this study, the effect of distance of the anode from the steel and level of corrosion on current distribution is investigated by applying a potential sweep and measuring the steel potential and current for specimens with three layers of steel at different depths. The findings from this study revealed an inverse relationship between cathodic polarisation with steel distance from the anode and that higher levels of corrosion can cause a more non-uniform current distribution favouring the closest bar to the anode.

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