Evaluation of the corrosion potential in armed concrete as a function of armature covering

2021 ◽  
Author(s):  
Lázaro Rodrigues Penna ◽  
Maria Luísa Freitas dos Santos Honório ◽  
João Victor Laurindo Siqueira ◽  
Diogo Pereira dos Santos Kropf
Keyword(s):  
Corrosion Potential ◽  
Concrete Structures ◽  
Concrete Cover ◽  
Potential Range ◽  
Hardened Concrete ◽  
Corrosion Monitoring ◽  
Potential Measurement ◽  
External Agents ◽  
Cover Thickness ◽  
Corrosion Of Steel

In concrete structures, it is not uncommon to observe the presence of pathological problems that can often be associated with high temperature range, inadequate execution of works, inefficient projects, materials without quality control, unprepared labor, harmful external agents, among others. Among the pathological manifestations of hardened concrete is the corrosion of steel reinforcement, directly influencing the durability and strength of concrete structures. The object of this research is to analyze the influence of concrete cover thickness and chloride contamination on the potential readings of reinforcement corrosion. Since the cover thickness has a direct influence on the potential readings in chloride contaminated concrete. The corrosion potential measurement method will be used as an electrochemical tool to assist in the corrosion monitoring of reinforced concrete structures. As a standard for the evaluation results, the corrosion potential range recommended by ASTM C 876: 2015 and its relationship with the possibility of corrosion is normally used. With the results obtained during the application of this method, it is possible to identify regions where the reinforcement presents corrosion and how the process of steel depassivation is distributed in the region under study. Therefore, it is expected to verify the influence that the concrete cover has on chloride contamination and also influence the values of the corrosion potential.

Corrosion of Steel Reinforcements in Concretes of Non-Coastal Areas - Case Study: Kigali, Rwanda

2018 ◽  
Vol 38 ◽  
pp. 60-66
Author(s):  
G. Abaho ◽  
M.R. Pranesh ◽  
G. Senthil Kumaran
Keyword(s):  
Reinforced Concrete ◽  
Pore Space ◽  
Concrete Structures ◽  
Coastal Areas ◽  
Concrete Cover ◽  
Advanced Materials ◽  
Corrosion Monitoring ◽  
Reinforced Concrete Structures ◽  
Dissolved Ions ◽  
Corrosion Of Steel

It is the function of concrete cover to protect reinforcement against corrosion from environmental attack. However, reinforced concrete structures in most cases suffer from corrosion of steel reinforcement and their service lives will be reduced. The steel in concrete is always prone to corrosion attack, and the reason being that concrete cover is porous in nature. Fluids and dissolved ions can impregnate through pore space or through cracks and come in contact with reinforcement. Preventive maintenance is the best corrosion control mitigation measure for reinforced concrete structures. This paper highlights the causes of corrosion in non-coastal areas like Kigali in Rwanda. Condition assessment of two reinforced concrete buildings in Kigali has been made based on structural survey. It was found that Crack width varies up to 2mm in column and beams. It is also suggested that to improve the life span of the columns and beams by retrofitting with advanced materials and the new structures are to be constructed with corrosion monitoring systems.

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.

scholarly journals Application of Thermal Image Data to Detect Rebar Corrosion in Concrete Structures

2019 ◽  
Vol 9 (21) ◽  
pp. 4700 ◽  
Author(s):  
Seunguk Na ◽  
Inkwan Paik
Keyword(s):  
Temperature Distribution ◽  
Distribution Curve ◽  
Concrete Structures ◽  
Electrochemical Corrosion ◽  
Detection Methods ◽  
Corrosion Monitoring ◽  
Rebar Corrosion ◽  
Infrared Cameras ◽  
Cover Thickness ◽  
The Impact

Rebar corrosion monitoring techniques have been used in studies involving embedded sensors that can detect changes in the corrosion currents and the polarization resistance of rebars in large structures. Defect detection methods that employ infrared cameras are useful non-destructive testing methods to detect defects in concrete structures. However, the measurement results from these methods would vary depending upon several factors that affect thermography. Because of these reasons, they have not been able to provide sufficient reliability. The goal of this study is to develop a technique that uses infrared cameras to quantitatively measure rebar corrosion rates. To examine the impact of the cover thickness, the experiment variables were set at cover thicknesses of 10, 20, and 30 mm and rebar corrosion ratios of 0%, 1%, 3%, 5%, 7%, and 10%. Each variable was tested and a total of 60 specimens were created (i.e., 54 specimens and 6 preliminary specimens). In this study, corrosion was applied using an electrochemical corrosion method that employs Faraday’s law, i.e., the law of conservation of electric charge. The test results of height, width, and area of temperature distribution curve were analyzed, the height of temperature distribution curve was increased as the heating time was grown. In addition, the area of temperature distribution was varied dependent upon the corrosion rate and cover thickness.

The Influence of Micro Algae on Corrosion of Steel in Fly Ash Geopolymer Concrete: A Preliminary Study

2012 ◽  
Vol 626 ◽  
pp. 861-866 ◽  
Author(s):  
Monita Olivia ◽  
Navid Moheimani ◽  
Reza Javaherdashti ◽  
Hamid R. Nikraz ◽  
Michael A. Borowitzka
Keyword(s):  
Fly Ash ◽  
Corrosion Potential ◽  
Concrete Structures ◽  
Algal Growth ◽  
Microbiologically Influenced Corrosion ◽  
Metallic Surface ◽  
Geopolymer Concrete ◽  
Preliminary Study ◽  
Corrosion Of Steel ◽  
The Impact

Chloride is not the only main cause of corrosion of reinforced concrete structures in seawater environment. Microorganisms, such as bacteria and microalgae, in the seawater can induce microbiologically influenced corrosion (MIC) that leads to degradation of the concrete structures by formation of biofilm on the metallic surface. In this preliminary study, the impact of microalgae on the corrosion of steel reinforced bars in fly ash geopolymer concrete was studied. Corrosion potential, algae cells number, and pH measurement were carried out for fly ash geopolymer concrete and a control mix (Ordinary Portland Cement) samples. The results indicate that the corrosion potential of fly ash geopolymer concrete was influenced by the cathodic reaction during photosynthesis activities. The geopolymer concrete in algae-inoculated medium was found to be more tolerant to algal growth than the control mix (OPC concrete). There was a positive correlation between algae cell densities and the potential reading of the geopolymer.

scholarly journals Corrosion potential: influence of moisture, water-cement ratio, chloride content and concrete cover

2017 ◽  
Vol 10 (4) ◽  
pp. 864-885 ◽  
Author(s):  
M. H. F. Medeiros ◽  
F. C. Rocha ◽  
R. A. Medeiros-JUNIOR ◽  
P. Helene
Keyword(s):  
Corrosion Potential ◽  
Statistical Significance ◽  
Chloride Content ◽  
Concrete Cover ◽  
Chloride Ions ◽  
Degree Of Contamination ◽  
Destructive Testing ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Cover Thickness

ABSTRACT The method of measuring the corrosion potential is used as an electrochemical tool for helping the monitoring of the corrosion of reinforcements of concrete structures. As a criterion for evaluating results it is common to use intervals of corrosion potential and their correlation with corrosion probability, as precognizes ASTM C 876:2015. With this criterion, it is possible to establish an overview of the thermodynamic situation of corrosion in the structure or in the test specimen in laboratory. However, the method is influenced by several factors related with the concrete, the environment and with procedures adopted at the moment of executing the readings. Aiming to provide information to guide the technical and scientific environment regarding the right use of this type of non-destructive testing, the objective of this work is to evaluate some possible factors influencing the reading of corrosion potential, such as: moisture content of the concrete, water/cement ratio, thickness of the concrete cover and degree of contamination by chlorides. Results indicate that moisture and degree of contamination of the concrete by chloride ions had a tendency of making the corrosion potential more electronegative. Besides, it was verified that the influence of the cover is different for the case of contaminated concrete (1% of chlorides by mass of cement) and not contaminated with chlorides: the influence of the thickness of the cover, in the case of concrete contaminated by chlorides, was inversely proportional, in other words, the greater the cover thickness is, the less electronegative the value of the corrosion potential will be. On the other hand, in cases of concretes without chlorides, the effect of the cover thickness in the readings or corrosion potential was irrelevant. All this information was proved with 95% of statistical significance.

scholarly journals Performance evaluation of plastic spacers: proposal and development of evaluation methods

2016 ◽  
Vol 9 (6) ◽  
pp. 911-952
Author(s):  
M. F. F. Menna Barreto ◽  
◽  
A. P. Maran ◽  
D. C. C. Dal Molin ◽  
J. R. Masuero
Keyword(s):  
Performance Evaluation ◽  
Reinforced Concrete ◽  
Concrete Structures ◽  
Concrete Cover ◽  
International Standards ◽  
Performance Criteria ◽  
Reinforced Concrete Structures ◽  
And Performance ◽  
Cover Thickness ◽  
Brazilian Standard

ABSTRACT The durability of reinforced concrete structures is highly dependent on the characteristics of the concrete cover to reinforcement and its thickness. The failure to obtain cover thickness is the factor with the largest influence on the premature corrosion of the reinforcement, which in turn is the main deterioration form of reinforced concrete structures. Studies indicate that the designed cover is not reached in the current constructions that adopt this structural solution, configuring a chronic, and not a sporadic problem. One of the observed causes for the failure in obtaining the minimum standardized cover is the incorrect use of spacers and the use of inadequate spacers. This is made more serious by the absence of a Brazilian standard to regulate the product and its use and, consequently, the absence of a quality certification from the responsible regulating agency. Focusing on spacers, requirements and performance criteria were proposed, in addition to methods for their assessment, with most being taken and adapted from international standards. Subsequently, some spacers available on the market were effectively tested according to the proposed methodology. No spacer model proved to be satisfactory according to the established performance approach. However, for each criteria and assessment methods proposed, there was, at least, one spacer model at the market which satisfied them, so it can be said that the criteria and methods are suitable for spacers performance evaluation. Faced with the performance diversity of the spacer models on offer, the need for a regulatory Brazilian standard for this product was confirmed in order to delimit the quality of spacers available on the market and to eliminate this variable as one of the causes for not obtaining the correct covering.

The Impact of Concrete Cover Thickness and Chemical Alkalinity on Reinforcement Corrosion

2014 ◽  
Vol 1065-1069 ◽  
pp. 1957-1963
Author(s):  
Xiu Jing Zhou ◽  
Jia Ming Shu ◽  
Ji Dong Zhang ◽  
Yong Xian Yan ◽  
Wei Zhong Gan
Keyword(s):  
Corrosion Potential ◽  
Concrete Cover ◽  
Experimental Measurements ◽  
Reinforcement Corrosion ◽  
Atmospheric Conditions ◽  
Alkali Aggregate Reaction ◽  
Structural Durability ◽  
Cover Thickness ◽  
Standard Limit ◽  
The Impact

Based on the mechanism of reinforcement corrosion in concrete structures and the experimental measurements of corrosion potential and resistance, this paper investigates the impact of concrete cover thickness and chemical alkalinity on reinforcement corrosion. Experimental results show that the rate of reinforcement corrosion decreases as the thickness of concrete cover of reinforcement increases. Moreover, given no risk of alkali-aggregate reaction, raising the chemical alkalinity of concrete cover helps maintain passivation of reinforcement. Additionally, under general atmospheric conditions, cracks that are not along bars barely affect structural durability if the width of cracks is smaller than its standard limit.

Passing Aged Years to Polarization Characteristics of the Steel Bar Embedded in Mortar Specimen (W/C:0.4)

2013 ◽  
Vol 821-822 ◽  
pp. 1227-1231
Author(s):  
Sung Yul Lee ◽  
Jong Pil Won ◽  
Dong Hyun Park ◽  
Jae Hyun Jeong ◽  
Kyung Man Moon
Keyword(s):  
Polarization Curve ◽  
Anodic Polarization ◽  
Corrosion Potential ◽  
Anodic Polarization Curve ◽  
Industrial Society ◽  
Positive Direction ◽  
Potential Measurement ◽  
Mortar Specimen ◽  
Steel Bar ◽  
Cover Thickness

The structures of reinforced concrete has been extensively increased with rapid development of industrial society. Furthermore, these reinforced concretes are often exposed to severely corrosive environments such as sea water, contaminated water, acid rain and seashore etc.. Thus, the corrosion problem of a steel bar embedded in the concrete is very important in terms of the safety and economic points of view. In this study, a multiple mortar test specimen (W/C:0.4) that had six types of cover thickness was prepared and immerged in flowing seawater for five years. And the effects of cover thickness and immersion years on the corrosion properties of the steel bars were investigated using electrochemical methods such as measuring corrosion potential, anodic polarization curve, and impedance. At the beginning of immersion (0 year), corrosion potentials exhibited increasingly nobler value with increasing the cover thickness. However, after being immersed for 5 years, the corrosion potentials conversely shifted in the positive direction with decreasing the cover thickness. As a result, the relationships between corrosion potential and cover thickness were not in good agreement with each other after 5 years. In addition, after 5 years, the thinner cover thickness, the higher value of impedance at 0.01Hz. It is considered that corrosive products deposited on the surface of the steel bar embedded in mortar specimen in the case of thinner cover thickness played the role as a resistance polarization which resulted in decreasing the corrosion current density. Consequently, it seemed to be somewhat problem that evaluation on the corrosion property in reinforced steel would be estimated by only the corrosion potential measurement. Therefore, it is suggested that we should take into account various parameters such as cover thickness, corrosion potential, and immersed years etc. for its accurate assessment. Keywords : Cover thickness, Corrosion potential, Anodic polarization curve, Impedance, Resistance polarization

Corrosion monitoring and root cause identification in high solids concentrators

TAPPI Journal ◽  
2016 ◽  
Vol 15 (7) ◽  
pp. 467-477
Author(s):  
PASI NIEMELAINEN ◽  
MARTTI PULLIAINEN ◽  
JARMO KAHALA ◽  
SAMPO LUUKKAINEN
Keyword(s):  
Paper Industry ◽  
Black Liquor ◽  
Construction Materials ◽  
Open Circuit ◽  
Process Conditions ◽  
Potential Range ◽  
Corrosion Monitoring ◽  
General Corrosion ◽  
High Solids ◽  
Passive Area

Black liquor high solids (about 80%) concentrators have often been found to suffer from aggressive corrosion. In particular, the first and second effect bodies are susceptible to corrosion attacks resulting in tube leaks and wall thinning, which limit the availability and lifetime of evaporator lines. Corrosion dynamics and construction materials have been studied extensively within the pulp and paper industry to understand the corrosion process. However, it has been challenging to identify root causes for corrosion, which has limited proactive measures to minimize corrosion damage. Corrosion of the first phase concentrator was studied by defining the potential regions for passive area, stress corrosion cracking, pitting corrosion, and general corrosion. This was achieved by using a technique called polarization scan that reveals ranges for the passive area in which the equipment is naturally protected against corrosion. The open circuit potential, also known as corrosion potential, and linear polarization resistance of the metal were monitored online, which allowed for definition of corrosion risks for stainless steel 304L and duplex stainless steels 2205 and SAF 2906. An online temperature measurement added insight to the analysis. A process diagnostics tool was used to identify root causes of the corrosion attacks. Many of the root causes were related to process conditions triggering corrosion. Once the metal surface was activated, it was difficult to repassivate the metal naturally unless a sufficient potential range was reached.

Passive corrosion control and active corrosion prevention of the reinforced concrete structures by electrochemical chloride removal and inhibitors

2013 ◽  
Vol 61 (1) ◽  
pp. 32-37 ◽  
Author(s):  
Guofu Qiao ◽  
Yi Hong ◽  
Tiejun Liu ◽  
Jinping Ou
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Concrete Cover ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Corrosion Control ◽  
Cell Potential ◽  
Content Type ◽  
Chloride Removal ◽  
Active Corrosion

Purpose – The aim of this paper was to investigate the passive corrosion control and active corrosion protective effect of the reinforced concrete structures by electrochemical chloride removal (ECR) method and inhibitors approach, respectively. Design/methodology/approach – The concentration of aggressive chloride ion distributed from the reinforcing steel to the surface of the concrete cover was analyzed during the ECR processes. Besides, the half-cell potential, the concrete resistance R c , the polarization resistance R p and the capacitance of double layer C dl of the steel/concrete system were used to characterize the electrochemical performance of the concrete prisms. Findings – The effectiveness of ECR could be enhanced by increasing the amplitude of potential or prolonging the time. Inhibitor SBT-ZX(I) could successfully prevent the corrosion development of the reinforcing steel in concrete. Originality/value – The research provides the scientific basis for the practical application of ECR and inhibitors in the field.

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