scholarly journals Chemical Composition of Corrosion Products of Rebar Caused by Carbonation and Chloride

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Jundi Geng ◽  
Junzhe Liu ◽  
Jiali Yan ◽  
Mingfang Ba ◽  
Zhimin He ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Corrosion Products ◽  
Chloride Salt ◽  
Oxide Content ◽  
Passivation Film ◽  
Steel Bar ◽  
Steel Bars ◽  
Main Components ◽  
Corrosion Of Steel ◽  
Peak Value

The microstructures of steel bars were studied by X-ray photoelectron spectroscopy (XPS), and the mechanism of corrosion of steel bars under the corrosion factors was elucidated. The results show that the passivation film and corrosive surface of the steel surface in the solution of the chloride-containing salt were coarser and the surface state was denser. The main corrosion products are FeOOH and FeO. The surface of the steel immersed in the simulated carbonized solution had loose pores. The main components are FeOOH, Fe3O4, and Fe2O3. The surface of the steel bar has a large amount of yellowish brown corrosion products in the simulated carbonization and chloride salt. The surface of the corrosion products was stripped and the main components are FeOOH, Fe3O4, and FeCl3, where the content of FeOOH is as high as 60%. The peak value of iron is gradually increased from the simulated chloride salt solution to the carbonized solution to the combined effect of carbonation and chloride salt; the iron oxide content is increased and corrosion of steel is obviously serious.

scholarly journals Experimental Analysis of Reinforcement Rust in Cement under Corrosive Environment

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 241
Author(s):  
Xiaozhen Li ◽  
Hui Wang ◽  
Jianmin Wang ◽  
Junzhe Liu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Steel Corrosion ◽  
Corrosion Products ◽  
Chloride Salt ◽  
Corrosive Environment ◽  
Cement Slurry ◽  
Passivation Film ◽  
Chloride Environment ◽  
Corrosive Environments ◽  
Structural Layer

In this work, the microstructure characteristics of corrosion products of reinforcement under a corrosive environment with chloride, carbonation and the combination of chloride-carbonization were studied by x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy/energy spectroscopy (SEM-EDX). The results indicate that the outside of the passivation film reacts with the cement slurry to produce Fe–SiO4 in all three corrosive environments. The inner side is not completely corroded. The morphology of the corrosion is different in the three environments. In a chloride environment, corrosion products have obvious cracks, and the local layered structure is dense. In a carbonation environment, the surface of the steel corrosion shows a uniform granular structure and loose texture. With the combination of chloride and combination, the surface of the structural layer of steel corrosion was uneven and accompanied by protrusions, cracking and spalling occurred. The composition of the corrosion substances in the three corrosion environments are mainly composed of FeO, Fe3O4, Fe2O3 and Fe–SiO4. The content of iron oxide increases from a chloride salt, carbonization to the composite environment, indicating that the corrosion degree intensifies successively.

scholarly journals Influence of Rust Inhibitor on the Corrosion Resistance of Reinforcement in Cement Paste with Chloride

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 606
Author(s):  
Linchun Zhang ◽  
Ailian Zhang ◽  
Ke Li ◽  
Qian Wang ◽  
Junzhe Liu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Cement Paste ◽  
Photoelectron Spectroscopy ◽  
Electrical Resistance ◽  
Corrosion Properties ◽  
Passivation Film ◽  
Steel Bars ◽  
Assembly Unit ◽  
Chloride Environment ◽  
Rust Inhibitor

The electrical resistance and polarization effect of cement paste containing reinforcement were tested to research the anti-corrosion properties of steel bars in cement paste. Moreover, the microstructure and composition of passivation film and rust on the steel bars were studied. The water–cement ratio of the cement paste in this study was 0.3, with 0.5% NaCl, 1% NaNO2, and 1% Benzotriazole, and an assembly unit of 0.5% NaNO2 + 0.5% Benzotriazole by mass of cement was added to the cement to provide a chloride environment. X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were applied to research the composition of the passivation film and the microstructure of the cement paste, respectively. The results indicated that the samples with the assembly unit of 0.5% NaNO2 + 0.5% Benzotriazole showed the highest electrical resistance and polarization electrical resistance, while the specimens with 1.0% Benzotriazole showed the lowest electrical resistance and polarization electrical resistance. Moreover, the passivation film of steel bars weakened with increasing distance from the surface of the steel bars. Therefore, the corrosion of steel bars becomes more serious with increasing distance. Finally, the influence of the rust inhibitor on the corrosion resistance of steel bars in the specimens decreased in the following order: 0.5% NaNO2 + 0.5% Benzotriazole >1.0% NaNO2>1.0% Benzotriazole.

Influence of nitrite on chemical composition of passivation film of steel bars under the coupling effects of carbonization and chloride

2019 ◽  
Vol 66 (2) ◽  
pp. 230-235 ◽  
Author(s):  
Junzhe Liu ◽  
Jundi Geng ◽  
Hui Wang ◽  
Mingfang Ba ◽  
Zhiming He
Keyword(s):  
Chemical Composition ◽  
Photoelectron Spectroscopy ◽  
Chloride Solution ◽  
Layer Structure ◽  
Coupling Effects ◽  
Content Type ◽  
X Ray ◽  
Passivation Film ◽  
Steel Bars ◽  
Micro Structures

Purpose This paper aims to study the influence of NaNO2 on the chemical composition of passivation film. Design/methodology/approach X-ray photoelectron spectroscopy and X-ray diffraction were selected to determine the composition of passivation film of steel bars in mortar. The specimens were exposed to the chloride solution, carbonation environment and the coupling effects of chloride solution and carbonation. The chemical composition and micro structures at 0 and 5 nm from the outer surface of the passivation film of steel bars were analyzed. Findings Results showed that the nitrite inhibitor improved the forming rate of the passivation film and increased the mass ratio of Fe3O4 to FeOOH on the surface of steel bars. The component of Fe3O4 at 5 nm of the steel passivation film was more than that at 0 nm. Sodium ferrite in the pore solution was easily hydrolyzed and then FeOOH was formed. Therefore, due to the nitrite inhibitor, a “double layer structure” of the passivation film was formed to prevent steels bars from corrosion. Originality/value This is original work and may help the researchers further understand the mechanism of rust resistance by nitrite inhibitor.

Effects of Silanes on the Structure and Properties of Chromium-Free Passivation

2020 ◽  
Vol 12 (7) ◽  
pp. 1012-1018
Author(s):  
Fu Haiyang ◽  
Gao Bo ◽  
Zhou Yingwei ◽  
Xing Pengfei
Keyword(s):  
Photoelectron Spectroscopy ◽  
Film Formation ◽  
Resin Composite ◽  
Salt Spray ◽  
Neutral Salt ◽  
Silane Coupling Agents ◽  
Passivation Film ◽  
White Rust ◽  
Steel Surfaces ◽  
Corrosion Of Steel

Steel is one of the most widely used metal materials, and corrosion of steel surfaces is a serious problem. Traditional chromate passivation produces hexavalent chromium with high toxicity and carcinogenicity. To solve toxicity and pollution problems, a chromium-free passivation method was adopted to replace the traditional process. Based on the reaction mechanisms of some silane coupling agents, a new method of chromium-free passivation and anti-white rust production is presented in this paper. The chromium-free passivation process of an inorganic material-silane-resin composite was used in the study. The microstructure and corrosion resistance of a hot-dip galvanized sheet and silane passivation film were compared by using a neutral salt spray test, scanning electron microscopy, infrared spectroscopy and X-ray photoelectron spectroscopy. The mechanism of film formation was studied. The results show that the surface of the passivation film is dense and smooth without sharp protrusions and has a stable skeleton structure inside. The structure of the passive film is C=O, Si–O, C–Si, C–H, Si–O–Zn, Si–O–Si, etc. A chromium-free passivation film prepared with a disilane can effectively prevent penetration between the corrosive medium and matrix. After a 96 h corrosion test, the corrosion area is less than 5%, which meets the requirements of some industrial production processes.

Wave amplitude of embedded ultrasonic transducer-based damage monitoring of concrete due to steel bar corrosion

2021 ◽  
pp. 147592172110417
Author(s):  
Shunquan Zhang ◽  
Zijian Jia ◽  
Yuanliang Xiong ◽  
Ruilin Cao ◽  
Yamei Zhang ◽  
...  
Keyword(s):  
Ultrasonic Transducer ◽  
Steel Corrosion ◽  
Galvanic Current ◽  
Cell Potential ◽  
Accelerated Corrosion ◽  
Electrochemical Testing ◽  
Steel Bar ◽  
Steel Bars ◽  
Damage Process ◽  
Corrosion Of Steel

In this research, four embedded ultrasonic piezoelectric transducers were combined to form cross pair and opposite pair monitoring schemes for continuously monitoring the damage to different strength grades of concrete caused by the corrosion of reinforcements under accelerated corrosion conditions. The damage process was analyzed by combining the electrochemical effects of steel corrosion, that is, half-cell potential and galvanic current tests. Results show that the embedded ultrasonic transducer method can detect damage of concrete during steel corrosion and that each stage of damage can be determined from the plots of ultrasonic transducer data versus corrosion rate. The results further indicate that a combination of cross pair and opposite pair testing methods can more comprehensively reflect the damage to concrete caused by the expansion of corrosion of steel bars, than a single testing method. Since electrochemical testing can only depict the corrosion state of steel rebars, it is beneficial to use embedded ultrasonic measurements to monitor the damage process of concrete. The differences in damage between different strength grades of concrete, that is, the resistance to corrosion of steel bars and brittle failure, can be obtained from the plots of ultrasonic transducer data.

An Experimental Study on the Influence of Steel Bar Corrosion in the Structural Performance of Bridge Piers

2007 ◽  
Vol 348-349 ◽  
pp. 749-752
Author(s):  
In Seok Kang ◽  
Han Seung Lee ◽  
Hai Moon Jung ◽  
Tae Song Ahn
Keyword(s):  
Water Resistance ◽  
Steel Structures ◽  
Bridge Piers ◽  
Economic Losses ◽  
Korean Economy ◽  
Steel Bar ◽  
Steel Bars ◽  
Corrosion Of Steel ◽  
Resistance Performance ◽  
Near Future

Economic losses due to the corrosion of steel structures in concrete is almost about 4% of GNP. It is almost 70 billion dollars in America. Also, The Korean economy is expected to experience a 4～5% loss in GNP in the near future in by considering the industrial background that has been formed by heavy industries. Although deteriorations in concrete structures demonstrate a high diversity of factors, it finally comes down to the lowering of water resistance performance in structures based on the crack generation due to the corrosive expansion of steel bars. Thus, it is very important to investigate the lowering of water resistance performance in structures according to the level of the corrosion in steel bars.

Effects of Coating/Electroplating on Corrosion Resistance of Steel Bar in Reinforced Concrete

2012 ◽  
Vol 446-449 ◽  
pp. 3176-3179 ◽  
Author(s):  
Qun Zhou ◽  
Zhong He Shui ◽  
Yi De Xiao ◽  
Chang Sheng Xu
Keyword(s):  
Corrosion Resistance ◽  
Reinforced Concrete ◽  
Surface Treatment ◽  
Equivalent Circuit ◽  
Surface Coating ◽  
Corrosion Process ◽  
Steel Bar ◽  
Study Results ◽  
Steel Bars ◽  
Corrosion Of Steel

One of the main reasons for the damage of reinforced concrete is the expansion caused by corrosion of steel bar in concrete. In this paper, the equivalent circuit that inflects corrosion process of steel bars in reinforced concrete was analyzed, with the A.C.Impedance Spectrum method. And the effects of surface treatment of the bars on corrosion resistance of the reinforced concrete were investigated. Study results show that the surface coating (plating) on the built-in reinforcement can effectively prevent corrosion of steel bar, thereby enhancing the durability of concrete structures.

scholarly journals Electrochemical Study of Clean and Pre-Corroded Reinforcements Embedded in Mortar Samples with Variable Amounts of Chloride Ions

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6883
Author(s):  
María de las Nieves González ◽  
María Isabel Prieto ◽  
Alfonso Cobo ◽  
Fernando Israel Olmedo
Keyword(s):  
Corrosion Potential ◽  
Cement Mortar ◽  
Electrochemical Techniques ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Corrosion Products ◽  
The Other ◽  
Steel Bars ◽  
One Year ◽  
Corrosion Of Steel

The present study investigates the possibility of re-surfacing previously corroded reinforcements and the suitability of the two electrochemical techniques that are widely used to determine the state of corrosion of steel (the corrosion potential Ecorr and the corrosion rate icorr). In order to test this, 32 pre-corroded B500SD reinforcing steel bars have been used for one year, where half of the bars have been cleaned to eliminate corrosion products. The other half have been maintained with the generated corrosion products. Subsequently, the bars have been embedded in cement mortar samples with variable amounts of chloride ion, and Ecorr and icorr have been measured for 250 days. The results showed that it is not possible to rework the reinforcement without removing corrosion products and that it is not possible to predict the passive or active state of steel by measuring Ecorr only.

scholarly journals Study on the potential change of corroded reinforced concrete in ECE with MPC-CFRP as anode

2020 ◽  
Vol 319 ◽  
pp. 06005
Author(s):  
Yue Li ◽  
Xiuhu Zhang ◽  
S.M.Ali S. Hejazi
Keyword(s):  
Composite Material ◽  
Reinforced Concrete ◽  
Current Density ◽  
Good Effect ◽  
Steel Bar ◽  
Steel Bars ◽  
Cfrp Composite ◽  
Current Densities ◽  
Electrochemical Chloride Extraction ◽  
Corrosion Of Steel

Aiming at the rust removal requirements of reinforced concrete, the MPC-CFRP composite material was used as the external anode, and the Electrochemical chloride extraction (ECE) method was used to test the polarization curve of the steel bar under different ECE current densities, and the potential changes of the steel bar at different times were analyzed. The results show that the ECE system with MPC-CFRP as the external anode has a good effect of reducing the corrosion rate and the risk of corrosion of steel bars. The current density of 3A/m2is higher than that of 1A/m2in dechlorination efficiency. After 28 days of ECE, the current density of 1A/m2and 3A/m2can re passivate the reinforcement.

A new approach for describing pitting corrosion of steel bars in concrete

2017 ◽  
Vol 64 (6) ◽  
pp. 573-579
Author(s):  
Xinchun Guan ◽  
Lianjuan Miao ◽  
Hui Li ◽  
Jinping Ou
Keyword(s):  
Fractal Dimension ◽  
Pitting Corrosion ◽  
Depth Distribution ◽  
Local Corrosion ◽  
Content Type ◽  
Steel Bar ◽  
Steel Bars ◽  
Two Parameters ◽  
Corrosion Of Steel

Purpose The purpose of this study is to quantitively characterize pitting or local corrosion of steel bars. Characterization of pitting or local corrosion is important for steel bar corrosion research in concrete, which is still an unsolved problem for the reason that the pitting on corroded steel is distributed irregularly, besides the varied pitting depths. To solve this problem in a certain degree, two parameters were collectively used to find the pitting distribution and pitting depth distribution of corroded steel bar surface. Design/methodology/approach Corroded reinforcement bars were subjected to two different corrosive conditions to obtain the profile of the surface of corroded steel bar. The arithmetic mean deviation of the profile, Ra, also a roughness parameter, and the fractal dimension, D, were computed using MATLAB software from the data on corroded steel bar profiles scanned by a profile tester. Statistical analysis was performed to determine the parameters distribution of Ra. Findings Ra and D can assist gravimetric technique in defining the degree of pitting corrosion and make further understanding about the characterization of local or pitting corrosion. Originality/value Two parameters were collectively used to find the pitting distribution and pitting depth distribution of corroded steel bar surface, while many studies only study the fractal dimension of pitting corrosion. And, the relationship between these two parameters is studied when using them to describing the non-uniformity of pitting corrosion degree. Using these two parameters can much better describe the non-uniform degree of pitting corrosion.

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