• 한국구조물진단유지관리공학회 논문집
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• 제9권1호
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• pp.217-223
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• 2005

본 연구는 철근 콘크리트를 염해 및 중성화로부터 보호하여 철근의 부식을 방지하기 위한 3종류 표면 보호재의 성능을 평가한 것으로서, 표면 보호재를 사용한 시험편의 부식저항성능과 중성화 저항 성능을 평가하였다. 실험결과 3종류의 표면 보호재를 사용한 시험편에서는 철근의 부식저항성능이 매우 우수하게 나타났으며, 중성화 방지 성능도 우수하게 나타났다. 특히 발수성의 프라이머와 마감 코팅재를 함께 사용한 시험편은 철근의 부식과 중성화를 매우 크게 감소 시켰다.

• Corrosion Science and Technology
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• 제6권1호
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• pp.7-11
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• 2007

In this study, new evaluation method for the stability and corrosion resistance properties of passive films has been suggested by means of observation of self-activation process in open-circuit state and galvanostatic nanoscale reduction test. The experiments were performed for air-formed oxide film in case of plain carbon steel, and for anodically passivated films formed in aqueous sulfuric acid solutions in case of titanium and 304 stainless steel. From these experimental results, we derived two parameters, $i_{0}$ and $q_{0}$, which characterize the self-activation process and the properties of passive film on a stainless steel surface. The parameter $i_{0}$ was defined as the rate of self-activation, and $q_{0}$, the reduced amount of charge during the self-activation process. In conclusion, it is considered that the stability and corrosion resistance of passive metals and alloys can be evaluated quantitatively by three parameters of $\tau_{0}$, $q_{0}$, and $i_{0}$, which easily obtain by means of observing the self-activation process and galvanostatic nanoscale reduction test.

• Corrosion Science and Technology
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• 제10권5호
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• pp.175-179
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• 2011

The transportation and deposition of iron corrosion products are important elements that affect both the steam generator (SG) integrity and secondary system in pressurized water reactor (PWR) nuclear power plants. Most of iron corrosion products are generated on carbon steel materials due to flow accelerated corrosion (FAC). The several parameters like water chemistry, temperature, hydrodynamic, and steel composition affect FAC. It is well established that the at-temperature pH of the deaerated water system has a first order effect on the FAC rate of carbon steels through nuclear industry researches. In order to reduce transportation and deposition of iron corrosion products, increasing pH(t) tests were applied on secondary system of A, B units. Increasing pH(t) successfully reduced flow accelerated corrosion. The effect of increasing pH(t) to inhibit FAC was identified through the experiment and pH(t) evaluation in this paper.

• 콘크리트학회논문집
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• 제11권3호
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• pp.171-179
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• 1999

The present research investigated the interaction among loading level, corrosion rate and flexural deflection of reinforced concrete beams. 10cm$\times$15cm$\times$110cm reinforced concrete beams were prepared and subjected to different levels of flexural loading, including 0%, 45% and 75% of the ultimate load. The beams with either a pre-load or a sustained load were also exposed to a laboratory environment with ponding and wetting/drying cycling at room temperature. Half cell potential and galvanized current measurements were taken to monitor corrosion process of reinforcing steel. After corrosion initiation, external current was applied to some of the beams to accelerate corrosion propagation. The beam deflections were recorded during the entire tests. The results indicate that loading level has significant effect on corrosion rate. The beams under a sustained load had much higher corrosion rate than the pre-loaded and then unloaded beams. Significant corrosion may result in an increase in beam deflection and affect serviceability of the structure. The present research may provide an insight into structural condition evaluation and service life predictions of reinforced concrete.

• 상하수도학회지
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• 제22권3호
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• pp.379-387
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• 2008

The pH & alkalinity adjustment method by lime and carbon dioxide($CO_2$) for corrosion control in water distribution system was investigated to evaluate the corrosion characteristics of metal pipes, such as galvanized iron, copper, stainless steel, and carbon steel. When the pH in sand filtered and ozone+GAC treated water was increased with lime and $CO_2$ from 7.5 to 8.0, the concentration of residual chlorine decreased at higher pH and longer reaction time; the concentration of trihalomethane increased. The corrosion rate of coupons with corrosion control using lime and carbon dioxide was showed much smaller than those without corrosion control using pilot-scale simulated distribution system. The galvanized iron was corroded much faster than carbon steel, copper, and stainless steel. Especially, copper and stainless steel coupons were hardly corroded. The galvanized iron and carbon steel coupons with corrosion control were produced the corrosion products less than those without corrosion control by the results of environmental scanning electron microscope(ESEM) and energy dispersive x-ray spectroscopy(EDS) analyses. The galvanized iron coupon with pH and alkalinity adjustment by lime and carbon dioxide was detected about 30 percent of zinc, when the carbon steel was detected about 30 percent of calcium by calcium carbonate products formation. For the results of X-ray diffraction(XRD) analyses, the goethite(${\alpha}$-FeOOH) was identified as primary corrosion product of galvanized iron without corrosion control, while the Zinc oxide(ZnO) was found on corrosion products of galvanized iron coupon with corrosion control as the results of EDS analyses. However, the carbon steel corrosion products regardless of corrosion control were composed predominantly of maghemite(${\gamma}-Fe_2O_3$) and hematite(${\alpha}-Fe_2O_3$).

• Corrosion Science and Technology
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• 제8권5호
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• pp.188-192
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• 2009

A forced outage due to a steam generator tube leak in a Korean nuclear power plant was reported.1) Primary water stress corrosion cracking has occurred in many tubes in the plant, and they were repaired using sleeves or plugs. In order to develop proper repair criteria, it is necessary to understand the leak behavior of the tubes containing stress corrosion cracks. Stress corrosion cracks were developed in 0.1 M sodium tetrathionate solution at room temperature. Steam generator(SG) tubes with short cracks were successfully fabricated with a restricted solution contact method. The leak rates of the degraded tubes were measured at room temperature. Some tubes with 100 % through wall cracks showed an increase of leak rate with time at a constant pressure.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.67-70
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• 2007

A methodology to evaluate fatigue vulnerability of steel bridge members affected by corrosion and truck traffic variation is proposed. A fatigue limit state function including corrosion and traffic variation effects is established to make the criterion whether the steel bridge member is damaged by fatigue. Corrosion effects are expressed as increase of the average corrosion depth, and the traffic variation effects are modeled as the accumulated number of stress cycles. Reliability analysis is carried out by Monte-Carlo simulation method for the fatigue limit state function. The methodology Proposed is verified by comparing reference study and applying for the steel bridge in service.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.653-658
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• 2001

Recent long-span bridges, such as Kwang-Ahn Grand bridge, Seo-Hae Grand Bridge, Young-Jong Grand Bridge, etc, have been designed and constructed near the shore. Thus, it needs to analyze the durability of marine concrete structures which are exposed to severe chloride environments. It is well known that corrosion of reinforcement steel in concrete is one of the major factors for the durability of concrete structures. The objective of this experimental study is to investigate the performance of impressed current system and corrosion inhibitors for the corrosion protection of reinforced concrete structures. Concrete test specimens were made with various test parameters, such as cover depth, steel diameter, compressive strength, direction and frequency of notch. For the efficient evaluation of these corrosion protection systems, these tests have been carried out in the shore.

• Computers and Concrete
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• 제5권6호
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• pp.545-558
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• 2008

The corrosion of RC structures demonstrates very complicated forms of deterioration intermingled together but all pointing to a decrease in the durability of RC structures due to the corrosion of reinforcing bars. Until now, nondestructive techniques, such as half-cell potential and polarization resistance, have been widely available in the world. The former provides information on the probability of corrosion while the latter is associated with information concerning corrosion rates. Inversion by the boundary element method (IBEM) was developed for considering concrete resistivity. The applicability of the procedure was examined through a numerical analysis and electrolytic tests for RC slabs. A distribution in such concrete resistivity is relatively inhomogeneous including cracks on the surface of slabs. Regarding cracks in concrete, the relative coefficient of concrete resistance was introduced to perform its analysis. Further, the procedure will be developed to identify the corroded region visually using 3-D VRML.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.177-180
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• 2006

Reinforced concrete has been widely used as a semi-permanent construction materials. However, sea sand, deicing salt, and marine condition might induce the corrosion of embedded reinforcement due to the penetration of chlorides in concrete structures. This reinforcement corrosion causes serious problems on safety and serviceability of structures during lifetime. Also, reinforcement corrosion may cause the collapse of structures in worst case, so that the corrosion problem is more and more intensely growing. The purpose of this paper is to provide the fundamental data for the mechanical effect of corrosion through evaluation on bond characteristics of reinforced concrete using corroded bars.