• Corrosion Science and Technology
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• 제22권4호
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• pp.273-286
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• 2023

Rebar is embedded in concrete to create reinforced concrete (RC). Rebar carries most of the tensile stress and gives compressively loaded concrete fracture resistance. However, embedded steel corrosion is a significant cause of concern for RC composite structures worldwide. It is one of the biggest threats to concrete structures' longevity. Due to environmental factors, concrete decays and reinforced concrete buildings fail. The type and surface arrangement of the rebar, the cement used in the mortar, the dosing frequency of the concrete, its penetrability, gaps and cracks, humidity, and, most importantly, pollutants and aggressive species all affect rebar corrosion. Either carbonation or chlorides typically cause steel corrosion in concrete. Carbonation occurs when carbon dioxide in the atmosphere combines with calcium within the concrete. This indicates that the pH of the medium is falling, and the steel rebar is corroding. When chlorides pass through concrete to steel, corrosion rates skyrocket. Consideration must be given to concrete moisture. Owing to its excellent resistance, dry concrete has a low steel corrosion rate, whereas extremely wet concrete has a low rate owing to delayed O₂ transfer to steel surfaces. This paper examines rebar corrosion causes and mechanisms and describes corrosion evaluation and mitigation methods.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.63-67
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• 2002

The induced chemical and salt solution in water or admixture are originated to the corrosion process of the steeo rebar. These liquids penetrate into concrete as the accompanied by the chemical reaction and cause to attack the steel rebar in concrete. Concrete surfaces which it exposed to deicing, water and sea water is allowed to enter the chlorides in the structures. To prevent from the source of corrosion and deterioration Is subjected to put an end to corrode or reduce to contaminate on the steel rebar. As this reason the MCI 2022 products are applied to the surface of concrete and steel rebar. The concrete samples were made of to the kind of four, i.e. RF, MR, MS, and MM. Corrosion inhibitor is applied to coat on the surface of concrete after it had been cured for 28days. Specimen were immersed in a 3.5％ sodium chloride solution. Concrete specimen were tested to determine the changes of the resistance polarization, Rp, over a 22 weeks period. MCI 2022 is significantly shown the corrosion inhibition of steel rebar in 3.5% NaCl solution. In the each different concrete sample, MS and MM is seemed to be better than others. The results are proofed that MCI 2022 is promised to maintain the inhibition of corrosion with high resistance polarization of the steel rebar in concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.112-113
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• 2021

Phosphate based inhibitor is playing a decisive role in inhibiting the corrosion of steel rebar in chloride condition. We have used different amount of ammonium phosphate monobasic (APMB) as corrosion inhibitor in mortar with different amount of chloride ions. The compressive strength, flexural strength, open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization resistance (PPR), scanning electron microscopy (SEM) and Raman spectroscopy were performed to access the effect of inhibitor on corrosion resistance. As the amount of inhibitor is increased, the compressive strength increased. The electrochemical results show that as the amount of inhibitor and chloride ions are increased, the total impedance and corrosion resistance of steel rebar increased attributed to the formation of the stable oxide films onto the steel rebar surface. It is suggested that APMB can work in high concentration of chloride ions present in concrete where phosphate ion helps in formation of stable and protective phosphate based oxide film.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.101-102
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• 2022

A new hydrazone derivatives namely (E)-N'-(4-(dimethylamino)benzylidene)-2-(5-methoxy-2-methyl-1H-indol-3-yl)acetohydrazide (HIND) has been confirmed for mitigating the corrosion of the steel rebar exposed to chloride contaminated synthetic concrete pore solution (ClSCPS). The mitigation of corrosion properties has been characterized by weight loss and electrochemical methods (Electrochemical impedance, Potentiodynamic polarization studies) as well as surface observations. The presence of HIND in the ClSCPS decreased the corrosion of steel rebar by adsorption of HIND molecules on the surface of the steel rebar. The optimal HIND concentration was 0.5 mmol/L, corresponding to an inhibition efficiency of 88.4%. The use of HIND enables the corrosion process to have a higher energy barrier. X-ray photo electron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS), and X-ray diffraction (XRD) spectroscopy interpretations confirmed that HIND mitigates the corrosion attack on the surface steel rebar.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.63-64
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• 2021

The corrosion inhibition properties of conifer cone (Pinus resinosa) extract were studied in synthetic concrete pore solutions (SCPS) with and without chloride environments by electrochemical methods. The electrochemical impedance spectroscopy (EIS) revealed that the conifer cone (CC) extract showed promising inhibition behavior by diminishing the corrosion rate of steel rebar both solutions i.e. with and without chloride. The extract of conifer cone hinders the corrosion reaction between steel rebar and aggressive ions. Further, it can be verified that the up to 1000mg.L-1 of CC extract can able to reduce the corrosion rate of steel rebar in chloride contaminated concrete.

• Structural Engineering and Mechanics
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• 제30권6호
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• pp.713-732
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• 2008

Serviceability and durability of the concrete members can be seriously affected by the corrosion of steel rebar. Carbonation front and or chloride ingress can destroy the passive film on rebar and may set the corrosion (oxidation process). Depending on the level of oxidation (expansive corrosion products/rust) damage to the cover concrete takes place in the form of expansion, cracking and spalling or delamination. This makes the concrete unable to develop forces through bond and also become unprotected against further degradation from corrosion; and thus marks the end of service life for corrosion-affected structures. This paper presents an analytical model that predicts the weight loss of steel rebar and the corresponding time from onset of corrosion for the known corrosion rate and thus can be used for the determination of time to cover cracking in corrosion affected RC member. This model uses fully the thick-walled cylinder approach. The gradual crack propagation in radial directions (from inside) is considered when the circumferential tensile stresses at the inner surface of intact concrete have reached the tensile strength of concrete. The analysis is done separately with and without considering the stiffness of reinforcing steel and rust combine along with the assumption of zero residual strength of cracked concrete. The model accounts for the time required for corrosion products to fill a porous zone before they start inducing expansive pressure on the concrete surrounding the steel rebar. The capability of the model to produce the experimental trends is demonstrated by comparing the model's predictions with the results of experimental data published in the literature. The effect of considering the corroded reinforcing steel bar stiffness is demonstrated. A sensitivity analysis has also been carried out to show the influence of the various parameters. It has been found that material properties and their inter-relations significantly influence weight loss of rebar. Time to cover cracking from onset of corrosion for the same weight loss is influenced by corrosion rate and state of oxidation of corrosion product formed. Time to cover cracking from onset of corrosion is useful in making certain decisions pertaining to inspection, repair, rehabilitation, replacement and demolition of RC member/structure in corrosive environment.

• 한국표면공학회지
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• 제53권6호
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• pp.300-305
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• 2020

Corrosion of reinforcement steel rebar is a serious problem in a wide range of concrete application for buildings and infrastructures. Hydrophobizing surface treatments, such as self-assembled monolayer coating, edible oil-impregnation and silicone oil-impregnation were applied to solidified concrete. The hydrophobizing of concrete significantly reduces an absorption and transportation of water toward a steel rebar in concrete, so that the corrosion resistance of the steel rebar. In particular, the silicone oil-impregnation not only forms the hydrophobic monolayer on the concrete but also fills the inter-connected pores of concrete, thus the corrosion of steel rebar is significantly inhibited compared to the self-assembled monolayer coating and edible oil-impregnation. Therefore, the silicone oil-impregnation can be a promising candidate for preventing corrosion of steel rebar in concrete for durable performance and safety.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.255-260
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• 2003

The corrosion of steel rebars has been the major cause of the reinforced concrete deterioration. It is FRP rebar that is developed to solve problem of such steel rebar. FRP rebar in concrete structures should be used as a substitute of steel rebars for that cases in which aggressive environment produce high steel corrosion, or lightweight is an important design factor, or transportation cost increase significantly with the weight of the materials. But FRP rebar have only linearly elastic behavior; whereas, steel rebar has linear elastic behavior up to the yield point followed by large plastic deformation and strain hardening. Thus, the current FRP rebars are not suitable concrete reinforcement where a large amount of plastic deformation prior to collapse in required. The main objective of this study was to develop new type of hybrid FRP rebar. The manufacture of the hybrid FRP rebar was achieved pultrusion, braiding and filament winding techniques. Tensile and interlaminar shear test results of hybrid FRP rebar can provide its excellent tensile strength-strain behavior and interlaminar stress-strain behavior.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.73-74
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• 2022

The corrosion inhibitive effect of a new hydrazone-based heterocyclic compound for steel in simulated concrete pore solution with 3.5 wt.% sodium chloride was investigated by experimental and computational techniques. Electrochemical studies, up to 30 days of immersion, and surface analysis (X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscope (SEM)) were performed to assess the corrosion protection abilities of investigated compound for steel rebar. Results showed that adding the organic compound to the chloride contaminated concrete pore solution decreased the corrosion rate of the steel rebar thanks to the effective adsorption of inhibitor molecules. After 30 days of immersion of steel rebar in inhibited chloride contaminated synthetic concrete pore solution, the inhibition efficiency exceeded 80% at low concentration of 1 mmol/L. Computational studies by Density Functional based Tight Binding (DFTB) method revealed the formation of covalent bonds between the hydrazone molecule and the iron surface.

• Advances in concrete construction
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• 제8권4호
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• pp.247-255
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• 2019

Several reinforced concrete structures that get deteriorated by rebar corrosion are retrofitted using Carbon Fiber Reinforced Polymer (CFRP). When rebar comes in direct contact with CFRP, rebar may corrode, as iron is more active than carbon. Progression of corrosion of rebar in strengthened RC structures has been carried out when rebar comes in direct contact with CFRP. The experimentation is carried out in two phases. In phase I, corrosion of bare steel bar is monitored by making its contact with CFRP. In phase II, concrete specimens with surface bonded CFRP were casted and subjected to the realistic exposure conditions keeping direct contact between rebar and CFRP. Progression of corrosion has been monitored by various parameters: Half-cell potential, Tafel extrapolation and Linear Polarisation Resistance. On termination of exposure, to find residual bond stress between rebar and concrete, pull-out test was performed. Rebar in contact with CFRP has shown substantially higher corrosion. The level of corrosion will be more with more area of contact.