• KCI Concrete Journal
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• v.14 no.4
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• pp.145-150
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• 2002

Reinforced concrete is inherently a durable composite material. When properly designed for the environment to be exposed and carefully constructed, reinforced concrete is capable of giving maintenance-free performance. However, unintentionally using improper materials such as non-washed sea sand having much salt together with poor controlled quality, or the concrete are placed in highly severe environment such as marine atmosphere, the corrosion of reinforcing steel in concrete becomes one of the most significant concerns of concrete. The purpose of this experimental research is to evaluate the performance of corrosion inhibitors for normal strength and high strength concrete, and to propose desirable measures for controlling corrosion of reinforcing steel in concrete. Test specimens in normal strength and high strength concrete were made with and without corrosion inhibitors. The accelerated corrosion test for reinforcing steel in concrete was adopted in accordance with JCI-SC3, which required the periodic 20 cycles for 140 days. One cycle includes 3 days for the wetting condition of $65^{\circ}C$ and $90\%$ RH, and 4 days for the drying condition of $15^{\circ}C\;and\;60\%$ RH. It was observed from the test that corrosion inhibitors in normal strength concrete and high strength concrete showed excellent corrosion resistance for reinforcing steel in concrete, but the silica fume in high strength concrete was found to have a negligible corrosion resistance if not used with corrosion inhibitors, since the chloride corrosion threshold limit in concrete containing silica fume without corrosion inhibitor was found to be considerably smaller than that of the case with corrosion inhibitor.

• Corrosion Science and Technology
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• v.12 no.2
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• pp.85-92
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• 2013

This work is concerned with an evaluation of dynamic boric acid corrosion (BAC) of low alloy steel for reactor pressure vessel of a pressurized water reactor (PWR). Mockup test method was newly established to investigate dynamic BAC of the low alloy steel under various conditions simulating a primary water leakage incident. The average corrosion rate was measured from the weight loss of the low alloy steel specimen, and the maximum corrosion rate was obtained by the surface profilometry after the mockup test. The corrosion rates increased with the rise of the leakage rate of the primary water containing boric acid, and the presence of oxygen dissolved in the primary water also accelerated the corrosion. From the specimen surface analysis, it was found that typical flow-accelerated corrosion and jet-impingement occurred under two-phase fluid of water droplet and steam environment. The maximum corrosion rate was determined as 5.97 mm/year at the leakage rate of 20 cc/min of the primary water with a saturated content of oxygen within the range of experimental condition of this work.

• Computers and Concrete
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• v.33 no.6
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• pp.631-642
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• 2024

The present study concerns the corrosion mitigation of electrochemical chloride extraction (ECE) in concrete structure. Concrete specimen was fabricated with 5.0% chloride in cast, while the other specimen was exposed to 4.0M NaCl solution for 1 year to accelerate corrosion of steel. Then, the ECE was applied to the concrete specimen with 1000 mA/m² of the current density for 2, 4 and 8 weeks, respectively. During the ECE, the corrosion current density and corrosion potential were regularly monitored. As a result, the ECE was very effective in mitigating the degree of corrosion on the steel surface. The corrosion current density was significantly reduced from thousands to decades mA/m², while the corrosion potential was mostly shifted to positive direction. Assuming that the corrosion starts at 1.0 mA/m² of the corrosion current density or/and -275 mV vs SCE of the corrosion potential, the ECE could not fully achieve the repassivation of the steel, although its degree was lowered more or less depending on the duration of the treatment and type of chloride contamination. A visual examination confirmed that an increase in the duration of the treatment could lower the rust formation, but never fully removed all rust stains.

• Corrosion Science and Technology
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• v.10 no.3
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• pp.87-94
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• 2011

The typical corrosion prevention method inside the steel upper box girder in a suspension bridge involves the use of paints. However, in an effort to reduce environmental impact and cost, the suspension portion of the Yeongjong Bridge, Korea utilizes dehumidification systems to control humidity and prevent corrosion inside its box girder. Maintaining a uniform humidity distribution at the proper level inside the box girder is critical to the successful corrosion control. In this study, the humidity and the resultant atmospheric corrosivity inside the box girder of the Yeongjong Bridge was monitored. The corrosion rate of the steel inside the box girder was obtained using thin-film electrical resistance (TFER) corrosion sensors. Time-of-wetness (TOW) measurements and the deposition rates of atmospheric pollutants such as $Cl^{-}$ and $SO_{x}$ were also obtained. Classification of the atmospheric corrosivity inside the box girder was evaluated according to ISO 9223. As a result, no corrosion was found in the upper box girder, indicating that the dehumidification system used in the Yeongjong Bridge is an effective corrosion control method.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.220-225
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• 2003

In order to develop a method of corrosion fatigue design and estimate reliability of TMCP steel using as the material of heavy industries and plants, its corrosion susceptibilities and corrosion fatigue life considering corrosion degradation were investigated. From the results, the corrosion characteristic of TMCP steel is very susceptible in 3.5wt.% NaCl solution. Its susceptibility was linearly increased with the solution temperature increase. The potential difference due to the crack growth behavior in $25^{\circ}C$, 3.5wt.% NaCl solution is very susceptible. And it was found that stress amplitude has a linear relationship with the critical potential. Therefore, it is expected that the corrosion fatigue life of TMCP steel can be nondestructively predicted using the DCPD method.

• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.1962-1971
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• 2022

The liquid lead-lithium (Pb-17Li) blanket has many applications in fusion reactors due to its good tritium breeding performance, high heat transfer efficiency and safety. The compatibility of liquid Pb-17Li alloy with the structural material of blanket under magnetic field is one of the concerns. In this study, corrosion experiments China low activation martensitic (CLAM) steel and 316L steel were carried out in a forced convection Pb-17Li loop under 1.0 T magnetic field at 480 ℃ for 1000 h. The corrosion results on 316L steel showed the characteristic with a superficial porous layer resulted from selective leaching of high-soluble alloy elements and subsequent phase transformation from austenitic matrix to ferritic phase. Then the porous layers were eroded by high-velocity jet fluid. The main corrosion mechanism of CLAM steel was selective dissolution-base corrosion attack on the microstructure boundary regions and exclusively on high residual stress areas. CLAM steel performed a better corrosion resistance than that of 316L steel. The high Ni dissolution rate and the erosion of corroded layers are the main causes for the severe corrosion of 316L steel.

• Corrosion Science and Technology
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• v.2 no.2
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• pp.98-101
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• 2003

The Electrical Resistance Probe of carbon steel and weight loss coupons were exposed in atmosphere and in the lake water of Hanoi. The comparison of data received by two methods after one year exposure was presented. The correspondence of the data of these methods on the exposure time in both environments showed a capacity of using Electrical Resistance Probe in Vietnamese natural corrosion testing of Carbon steel.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.04a
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• pp.73-78
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• 1993

This study was performed for the purposes of estimating steel corrosion of concrete structures under the environment of seawater. The corrosion of steel was accelerated in artificial seawater with seven kinds of specimen which was embedded in mortar. By measuring choride content in mortar, half cell potential and corrosion area ratio, the degree of steel corrosion can be assumed.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.197-202
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• 1998

The corrosion of steel reinforcements in concrete is of much concern in recent years. The mechanism of corrosion, however, is not clear yet. This study is focused on the corrosion of steel induced by internal chlorides in concrete at early ages. To examine the critical concentration of steel, half-cell potential, chemical composition of expressed pore solutions of mortars and rate of corrosion area were observed with respect to additions of chlorides, types of binders, water-binders ratio.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.475-476
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• 2010

Hydration products formed on the steel surface may impose the resistance to corrosion of steel when a concrete is exposed to a salt environment. In the present study, ordinary Portland cement (OPC), calcium aluminate cement (CAC) and calcium hydroxide are applied as coating materials on the steel surface to consider the hydrations of each binder at corrosion. Corrosion is measured in terms of the corrosion potential and galvanic current to detect the effects in mitigating the corrosion behavior.