scholarly journals Time Scale of Chloride-Induced Corrosion on Circular Section RC Linked Accelerated Test to Natural Corrosion

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Yue Zhang ◽  
Fangyan Lan ◽  
Mi Zhou ◽  
Ke Wang
Keyword(s):  
Time Scale ◽  
Time Correlation ◽  
Corrosion Process ◽  
Accelerated Corrosion ◽  
Circular Section ◽  
Rc Structures ◽  
Chloride Corrosion ◽  
Faraday’S Law ◽  
Chloride Environment ◽  
Natural Corrosion

The time scale in accelerated decay is essential for studying the durability of reinforced concrete (RC) structures exposed to the chloride corrosion environment. An accelerated corrosion test (ACT) was carried out on RC specimens were conducted under different chloride concentrations and applied voltages, with the information of steel measured. A novel prediction model of the complete corrosion process is proposed to evaluate the time correlation between accelerated decay and natural corrosion. The corrosion process of RC is divided into two stages: corrosion initial stage and corrosion stage of reinforcement. For the first stage, the coefficient of circular section members is presented. For the second stage, the accelerated factor of the test for the natural environment is proposed based on the Arrhenius-type and Faraday’s law. It is calculated by making regressions among some values of parameters, while moving to natural corrosion are extrapolating. The accelerating effect of applied voltages increases in the low-chloride environment, which is better than that in the high-chloride environment. This study provides calibration of the time scale for laboratory tests to analyze the performance of RC structures after corrosion.

On Comparison between Reinforcement Electricity Accelerated Corrosion and Natural Corrosion of Concrete

2013 ◽  
Vol 357-360 ◽  
pp. 676-679 ◽  
Author(s):  
Sen Li ◽  
Jun Yin Yan ◽  
Xiao Gang Wang
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Rate ◽  
Experimental Research ◽  
Comparative Research ◽  
Corrosion Process ◽  
Common Method ◽  
Corrosion Mechanism ◽  
Accelerated Corrosion ◽  
Electric Flux ◽  
Natural Corrosion

Electricity accelerated corrosion is a common method to obtain corroded reinforced concrete specimens in current experimental research, and it has some relevance and differences with natural corrosion. The paper undertakes a detailed comparative research on the relevance and differences of the two corrosion conditions from the corrosion mechanism, the corrosion process, the corrosion rate, the electric flux and corrosion features, and this provide a better understanding of the research achievements based on accelerated corrosion.

Corrosion of Reinforced Concrete in Accelerated Tests

2012 ◽  
Vol 610-613 ◽  
pp. 485-489
Author(s):  
Wan You Zhang ◽  
Rui Yuan Zhang ◽  
Lijuan Xi
Keyword(s):  
Reinforced Concrete ◽  
Surface Morphology ◽  
Steel Corrosion ◽  
Potential Change ◽  
Accelerated Tests ◽  
Accelerated Corrosion ◽  
Faraday’S Law ◽  
Full Immersion ◽  
Natural Corrosion

In order to study the correlation between accelerated corrosion and natural corrosion, reinforced surface morphology, steel potentials and corrosion quality were investigated by using full immersion and half immersion in this paper. The results showed that the effort of half immersion accelerated corrosion was similar to natural corrosion, and each of the tendencies of potential change was same, but the mechanisms of corrosion were different. The degree of steel corrosion, estimated by Faraday’s law, was slightly higher than the level of actual corrosion.

scholarly journals Degradation Monitoring in Reinforced Concrete with 3D Localization of Rebar Corrosion and Related Concrete Cracking

2021 ◽  
Vol 11 (15) ◽  
pp. 6772
Author(s):  
Charlotte Van Steen ◽  
Els Verstrynge
Keyword(s):  
Reinforced Concrete ◽  
Degradation Mechanism ◽  
Heterogeneous Material ◽  
Corrosion Damage ◽  
Corrosion Process ◽  
Internal Damage ◽  
Rc Structures ◽  
Degradation Monitoring ◽  
Rebar Corrosion ◽  
Width Measurements

Corrosion of the reinforcement is a major degradation mechanism affecting durability and safety of reinforced concrete (RC) structures. As the corrosion process starts internally, it can take years before visual damage can be noticed on the surface, resulting in an overall degraded condition and leading to large financial costs for maintenance and repair. The acoustic emission (AE) technique enables the continuous monitoring of the progress of internal cracking in a non-invasive way. However, as RC is a heterogeneous material, reliable damage detection and localization remains challenging. This paper presents extensive experimental research aiming at localizing internal damage in RC during the corrosion process. Results of corrosion damage monitoring with AE are presented and validated on three sample scales: small mortar samples (scale 1), RC prisms (scale 2), and RC beams (scale 3). For each scale, the corrosion process was accelerated by imposing a direct current. It is found that the AE technique can detect damage earlier than visual inspection. However, dedicated filtering is necessary to reliably localize AE events. Therefore, AE signals were filtered by a newly developed post-processing protocol which significantly improves the localization results. On the smallest scale, results were confirmed with 3D micro-CT imaging, whereas on scales 2 and 3, results were compared with surface crack width measurements and resulting rebar corrosion levels.

Influence of Geometry Parameters on Durability of Concrete Structures Exposed to Chloride Environment

2012 ◽  
Vol 204-208 ◽  
pp. 3194-3200
Author(s):  
Xin Gang Zhou ◽  
Hui Xia
Keyword(s):  
Concrete Structures ◽  
Chloride Content ◽  
Chloride Diffusion ◽  
Rectangular Section ◽  
Circular Section ◽  
Concrete Members ◽  
Numerical Stimulation ◽  
Numerical Computing ◽  
Chloride Environment ◽  
Cover Thickness

Finite difference method (FDM) is used to numerical stimulation analysis for chloride diffusion in concrete. By numerical computing, comparison of chloride content profile in different concrete members with different sectional shapes is made. Calculation and comparison show the chloride content prolife in rectangular and circular section has obvious difference. If the side length of rectangular section is equal to the diameter of circular section, as well as the material property and environment, the chloride content in rectangular section is higher than that in that in circular section. In the calculation example, the chloride content at the depth of reinforcement of circular section is about 50-60% that of rectangular section. This tendency is more remarkable in less section dimension, as well as less cover thickness. With the increasing of section, the ratio of difference becomes to be less until to a constant value. In durability design and service life prediction of concrete structures, the section shape and dimension influence should be taken to consideration.

Long-memory continuous-time correlation models

2003 ◽  
Vol 40 (04) ◽  
pp. 1133-1146 ◽  
Author(s):  
Chunsheng Ma
Keyword(s):  
Continuous Time ◽  
Time Scale ◽  
Long Memory ◽  
Moving Average ◽  
Time Correlation ◽  
Power Law Decay ◽  
Correlation Models ◽  
Moving Average Processes ◽  
Short Memory ◽  
Continuous Time Processes

This paper introduces a rather general class of stationary continuous-time processes with long memory by randomizing the time-scale of short-memory processes. In particular, by randomizing the time-scale of continuous-time autoregressive and moving-average processes, many power-law decay and slow decay correlation functions are obtained.

scholarly journals Influence of carbonation on the resistance of concrete structures to chloride penetration and corrosion

2019 ◽  
Vol 289 ◽  
pp. 08001
Author(s):  
Abbas S. AL-Ameeri ◽  
M. Imran Rafiq ◽  
Ourania Tsioulou
Keyword(s):  
Concrete Structures ◽  
Chloride Penetration ◽  
Reinforcement Corrosion ◽  
Half Cell ◽  
Rc Structures ◽  
Concrete Carbonation ◽  
Chloride Diffusivity ◽  
Carbon Dioxide Co2 ◽  
Chloride Environment ◽  
Corrosion Of Steel

Chloride-induced corrosion of steel rebar embedded in concrete is one of the major concerns influencing the durability of reinforced concrete structures. It is widely recognized that the carbonation in concrete affects the chloride diffusivity and accelerates the chloride-induced reinforcement corrosion. However, only very limited studies have dealt with this issue in the literature. The presence of service load related cracks also affects the reinforcement corrosion. This study aims to investigate the potential impact of concrete carbonation on the chloride penetration resistance, and degree of corrosion, in RC structures subjected to service related microcracks. The experimental programme involves casting of concrete prisms (100 x 100 x 500 mm) with different water-cement ratios (w/c) of 0.4, 0.5 and 0.6 and with four different crack widths (0, 0.05-0.15 mm, 0.15-0.25 mm and 0.25-0.35 mm). These samples were exposed initially to accelerated carbon dioxide (CO2) environment and then exposed to the accelerated chloride environment. Carbonation depth, chloride penetration, and the degree of corrosion (using half-cell) were experimentally measured. The results indicated that (i): The depth of carbonation increases with the increase in crack width and w/c ratio, (ii) chloride penetration depth in concrete structures increases significantly due to the influence of carbonation and (iii) half-cell corrosion potential increases significantly when carbonated concrete samples are exposed to the chloride environment relative to the uncarbonated concrete samples.

Electrochemical Noise Analysis of Chalcopyrite Carbon Paste Electrodes by Acidithiobacillus ferrooxidans

2007 ◽  
Vol 20-21 ◽  
pp. 83-86 ◽  
Author(s):  
Daniela G. Horta ◽  
Denise Bevilaqua ◽  
Heloísa A. Acciari ◽  
Oswaldo Garcia Jr. ◽  
Assis Vicente Benedetti
Keyword(s):  
Electrochemical Noise ◽  
Noise Analysis ◽  
Silver Ions ◽  
Chloride Ions ◽  
Corrosion Process ◽  
Electrochemical Cells ◽  
Carbon Paste ◽  
Mineral Salts ◽  
Accelerated Corrosion ◽  
Carbon Paste Electrodes

The electrochemical response of chalcopyrite was studied using electrochemical noise analysis (ENA). The assay was carried out under constant aeration using 30 mL in two electrochemical cells containing iron-free mineral salts solution. These cells were initially monitored for 56 hours. After 72 hours, 7.25×1010 cells mL-1 of A. ferrooxidans strain LR were added in both cells and monitored until 128 h. Subsequent to this period, 0.927 mmol L-1 of silver ions and 400 mmol L-1 of chloride ions were added each one separately. Both conditions were monitored until 168 hours. According to results obtained, it was observed that Cl- ions addition induced an accelerated corrosion process. However, there is a tendency of the system to reach the stationary state due to repassivation of the electrodic surface. In the other side, the Ag+ addition contributed for the maintenance of the oxidant atmosphere, in spite of controversial effect caused by considerable variations in the Rn values, resulting in a instability in the chalcopyrite reactivity.

Analysis on Fatigue of Natural Corrosion Steel Bars

2010 ◽  
Vol 163-167 ◽  
pp. 3237-3241 ◽  
Author(s):  
Shi Bin Li ◽  
Wei Ping Zhang ◽  
Xiang Lin Gu ◽  
Ci Mian Zhu
Keyword(s):  
Fatigue Life ◽  
Stress Level ◽  
Fatigue Tests ◽  
Power Exponent ◽  
Accelerated Corrosion ◽  
Negative Power ◽  
Axial Tensile ◽  
Attenuation Rate ◽  
Steel Bars ◽  
Natural Corrosion

To reasonablely assess the residual fatigue life of aged existing reinforced concrete(RC) bridges, axial tensile fatigue tests were conducted on fifteen naturally carbonation-induced corrosion steel bars. The fatigue test results indicate that the existence of corrosion pits reduces the fatigue life of steel bars significantly under the same fagitue stress; with the development of corrosion, the fatigue life of steel bars decays according to negative power exponent law approximately and the attenuation rate increases with stress level augment. The fatigue deterioration law of natural corrosion steel bars is similar to that of accelerated corrosion steel bars, but the attenuation rate is different from that of accelerated corrosion steel bars, and also the influence of stress level on the attenuation rate is just cross to that of accelerated corrosion steel bars. For the complexity of fatigue and corrosion, further pertinent conclusions remain to be confirmed.

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