• Corrosion Science and Technology
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• v.8 no.6
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• pp.223-226
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• 2009

Polymer coatings are commonly applied to metal substrates to prevent corrosion in aggressive environments such as high humidity and under salt water. Once the polymer coating has been breached, for example due to cracking or scratches, it loses its effectiveness, and corrosion can rapidly propagate across the substrate. The self-healing system we will describe prevents corrosion by healing the damage through a healing reaction triggered by the actual damage event. This self-healing coating solution can be easily applied to most substrate materials, and our dual-capsule healing system provides a general approach to be compatible with most common polymer matrices. Specifically, we expect an excellent anti-corrosion property of the self-healing coatings in damaged parts coated on galvanized metal substrates.

• Computers and Concrete
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• v.20 no.5
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• pp.511-519
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• 2017

The reliability of reinforced concrete structures is frequently compromised by the deterioration caused by reinforcement corrosion. Evaluating the effect caused by reinforcement corrosion on structural behaviour of corrosion damaged concrete structures is essential for effective and reliable infrastructure management. In lifecycle management of corrosion affected reinforced concrete structures, it is difficult to correctly assess the lifecycle performance due to the uncertainties associated with structural resistance deterioration. This paper presents a stochastic deterioration modelling approach to evaluate the performance deterioration of corroded concrete structures during their service life. The flexural strength deterioration is analytically predicted on the basis of bond strength evolution caused by reinforcement corrosion, which is examined by the experimental and field data available. An assessment criterion is defined to evaluate the flexural strength deterioration for the time-dependent reliability analysis. The results from the worked examples show that the proposed approach is capable of evaluating the structural reliability of corrosion damaged concrete structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.2
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• pp.191-198
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• 2005

This study was carried out to investigate quantitatively the relationship between the degree of rebar corrosion and the strength of reinforced concrete beams. After producing equations for the relationship between both the tensile properties of rebars and bond properties and the corrosion percentage of rebars, finite element analysis and bending tests were conducted for RC beams damaged by corrosion of tension main rebar. As a result, it was made that the strength of RC beams damaged by corrosion could be practically simulated by FEM analysis using experimentally determined material properties representing the bond and the mechanical characteristics of corroded rebars.

• KIEAE Journal
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• v.7 no.4
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• pp.141-146
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• 2007

It is necessary to guarantee the safety, serviceability and durability of reinforced concrete structures over their service life. However, concrete structures represent a decrease in their durability due to the effects of external environments according to the passage of time, and such degradation in durability can cause structural degradation in materials. In concrete structures, some degradations in durability increase the corrosion of embedded rebars and also decrease the structural performance of materials. Thus, the structural condition assessment of RC materials damaged by corrosion of rebars becomes an important factor that judges needs to apply restoration. In order to detect the damage of reinforced concrete structures, a visual inspection, a nondestructive evaluation method(NDE) and a specific loading test have been employed. However, obscurities for visual inspection and inaccessible members raise difficulty in evaluating structure condition. For these reasons, detection of location and quantification of the damage in structures via structural response have been one of the very important topics in system identification research. The main objective of this project is to develope a methodologies for the damage identification via static responses of the members damaged by durability. Six reinforced concrete beams with variables of corrosion position and corrosion width were fabricated and the damage detections of corroded RC beams were performed by the optimization and the conjugate beam methods using static deflection. In results it is proved that the conjugate beam method could predict the damage of RC members practically.

• Corrosion Science and Technology
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• v.6 no.3
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• pp.112-119
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• 2007

This paper presents the importance of corrosion control and protection technology with a real case study of heater tube rupture damaged by High temperature H2S-H2 corrosion in the refinery. The heater was operated at the Hydrocracking unit and the operation temperature and pressure was $340^{\circ}C$ and $18kg/cm^{3}$ respectively. Top side of the convection tube was thinned by high temperature hydrogen sulfide and hydrogen gas as a uniform corrosion and finally ruptured under operation pressure. Damaged area (Convection tube zone) was blocked by protection wall, so it was impossible to inspect with conventional nondestructive examination. Instead the elbow area which is out of the protection wall was inspected regularly to evaluate the corrosion rate of convection tube indirectly. However the operation temperature and the phase of the process stream was different between inside the chamber and outside the chamber. As a result, it caused severe corrosion to the horizontal convection tube inside the chamber comparing to the elbow outside the chamber. Finally convection tube was corroded more rapidly than the elbow and ruptured after 13 years operation. Because of the rupture, the heater was totally burned and the operation was stopped for 3 months until it has been reconstructed. To prevent this kind of corrosion problem and accident, corrosion control should be strengthened and protection technology should be improved.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.141-148
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• 2002

Repair were made for front pillar, center pillar and side-step panel for lightweight vehicles with head-on and 40% off-set collision of 15 km/h in a RCAR standard. The salt dilution was sprayed and the compression tests were performed for vehicles with and without anti-corrosional treatment after repair. After 764 hours of salt-dilt sprayed test without using anti-corrosion, the mean penetration depth fur corrosion was shown to be 58% of the thickness. The resulyed decrease in bending stiffness by 10∼20% can cause reduction of the residual life and crash-absorption capability for damaged vehicles. The corrosoin safety tests showed that the anti-corrosional treatment should be made to improve the safety characteristics for a or damaged car.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.254-257
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• 2006

Five bench scale specimens were used to evaluate corrosion performance of damaged epoxy-coated bars in chloride contaminated concrete. The test specimens were subjected 48 weekly cycles of ponding with sodium chloride solution and drying. Test results using linear polarization technique show that the current density of specimen with conventional steel becomes $0.715\;{\mu}A/cm^2$ indicating that the steel bars are in moderate or high corrosion condition. However, the corrosion rates of the specimens with damaged epoxy coated bars are much below $0.1\;{\mu}A/cm^2$ and the bars appears to be in passive condition. The corrosion protection performance provided by calcium nitrite is better than that of specimens with the other two inhibitors.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.3
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• pp.100-109
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• 2021

This study was examined the tensile strength change of a circular tubular member with artificial sectional damage on its surface to consider surface sectional damage by corrosion. The tensile strength tests were conducted using circular tubular specimens with artificial sectional damage considering sectional damaged height and width on its surface according to the corrosion level. From the tensile strength test results, it is confirmed that tensile strength of the circular tubular specimens was affected by the damaged circumference (damaged width), not damaged length (damaged height) and their tensile failures were appeared at the minimum section of the artificial sectional damage part. Nonlinear finite-element analyses were conducted considering equivalent sectional damage effect on sectional damaged part in tensile specimens to examine the change in the tensile strength of tubular specimens with artificial sectional damage since it is difficult to estimate the sectional damaged surface condition of the specimens clearly. From the nonlinear finite element analysis results for the tensile test specimens, tensile strengths of test specimens with irregular sectional damaged surface were relatively evaluated to be highly decreased than these of FE analysis model with equivalent sectional damage. Therefore, residual tensile strengths of tensile members with irregular sectional damage as local corrosion can be evaluated and predicted using correlation coefficient between tensile test results and FE analysis results with equivalent sectional damage.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.257-262
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• 1997

Reinforced concrete structures built on the seashore or in seawater are damaged from saltwater which cause to accelerate corrosion of reinforcing steel in concrete. Therefore, Corrosion of steel reinforcement of concrete structures become more and more serious, and prediction of service lives of concrete structures considering steel corrosion is needed much more. this research is to investigate basic physical properties of various corrosion inhibitors and to evaluate their corrosion resistance in concrete. The object of this study is develop appropriate corrosion protection systems so as to enhance the durability of concrete.

• Corrosion Science and Technology
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• v.8 no.4
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• pp.153-156
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• 2009

The water cooling system for VFD (Variable Frequency Drive) of a fossil fuel power plant was reported to be shut down due to a water leak at the metal connection of the heat-sink to the hoses. In order to identify the cause of the failure, the system was visually inspected, and corrosion products were analyzed with SEM equipped with EDX. The failure was observed repeatedly at the nipples of certain location, suggesting galvanic corrosion. In a U-shaped heat sink with two nipples, for inlet and outlet, only one nipple was corrosively damaged at the tip, while the other was not. Most of the corrosion products were observed at the sound nipple and in the filter, identified as $Cu(OH)_2$. Some other corrosion products, composed of mostly $Cu_2O$, were found at the corrosively attacked nipple. A fair amount of Cl was also detected on the surface of the damaged nipple. It was concluded that galvanic corrosion was occurred due to a current leakage over the whole system, and the damage was accelerated by the accumulated chlorine ions in the cooling water.