• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.239-247
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• 2004

When the concrete is subjected to chloride attack or carbonation, the passive steel normally initiate corrosion. By product of corrosion make volume of concrete expand 3 to 8 times and induce the stress which lead cracking and spalling of concrete. It result in the loss of the integrity of the concrete structures. Several corrosion inhibitors imported from America, Japan and Europe are currently being used to repair the concrete structures in Korea. However, questions has been raised for protective effect of the corrosion inhibitors which applied in steel reinforced concrete structures. Therefore, we investigated the influence of type and amount of corrosion inhibitors through the tests immersing in salty water. In addition, we developed the corrosion inhibitive agent treating to surface of concrete structures for improving resistance to penetration and corrosion of the steel reinforcement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.2
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• pp.85-92
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• 2007

In 1980s, a number of bridges with bare concrete deck were constructed on the Korea highway. After 20 years service, many bare concrete decks are still in good condition without special maintenance activity. Therefore, the application of the bare concrete deck is being reestimated from the view of construction and maintenance. As a part of the program, the characteristic of penetration(surface chloride and apparent diffusion coefficient) of de-icing salt into bare concrete bridge deck was analyzed in order to predict the service life of bridge on Korea highway.

• Computational Structural Engineering
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• v.7 no.4
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• pp.119-126
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• 1994

One of the most serious promblems in the concrete structures is cracking failure due to the several complicated reasons. These cracks are not only serious structural problems, but also lower the durability and deteriorate the structural shape, which cause the reinforcement rust in the open air and sea water. An analytical study was undertaken to investigate the cracking problems in the one of concrete caissons using Finite Element Method. This caisson is modelled with plate elements and truss elements for the walls and lifting cables respectively and analyzed in the every construction stages, such as lifting, moving, sinking, filling, towing, setting, and proposed reasonable construction methods for the concrete caisson structures.

• Journal of the Korea Concrete Institute
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• v.17 no.1 s.85
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• pp.43-49
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• 2005

In the concrete structures, the magnitude and distribution of the temperature due to the heat of hydration are related to the thermal properties of each component composed of the concrete, the initial temperature, the type of formwork, and the ambient temperature of exposed surfaces. Even though the reinforcing steel bar has completely different thermal properties, it has been excluded. In the thermal analysis on the concrete structures. In this study, finite element analysis was performed on the concrete structures including the reinforcing steel in order to investigate their effect on temperature and stress distribution due to the heat of hydration. As the steel ratio increased, the maximum temperature and the internal-external temperature difference decreased by 32.5% and 10%, respectively. It is clear that the inclusion of reinforcing steel bars on the heat of hydration analysis is indispensable to obtain realistic solutions for the prediction of the maximum temperature and stresses

• Journal of Korean Association for Spatial Structures
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• v.11 no.3
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• pp.67-76
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• 2011

Column base is very important part of steel structure because it transmits load to foundation in structure. Column base which is used frame construction in the inside and outside of the country is distributed into exposed-type, concrete encased and imbeded-type. Exposed-type column base is most profitable, if consider reuse and recycle of elements first of all. In this study, we proposed a new style exposed-type column base improved in performance for construction work and mechanical performance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.119-126
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• 2019

In case of RC(Reinforced Concrete) structures which are constructed in coastal areas, chloride ions in sea water corrode the steel rebar in concrete. Especially in coastal areas, RC structures are affected by not only immersion of sea water, but also tidal of sea water and airborne chloride ions. In this study, marine environment exposure tests are conducted, considering 3 types of exposure environments(immersion zone, tidal zone, splash zone) and the exposure periods of 180 days, 365 days, and 730 days. Also, the concrete mixtures for this study are established, considering 3 levels of W/B(Water to Binder) ratio(0.37, 0.42, 0.47) and 2 levels of substitution rate of Fly ash(0 %, 30 %). In all exposure environments, Fly ash concrete has lower apparent chloride diffusion coefficients than OPC concrete. It is thought that fly ash's pozzolan reaction improves chloride resistance of concrete. Fly ash concrete has up to 63.5 % of decreasing rate in 180 days of exposure and up to 55.8 % of decreasing rate in 730 days of exposure, based on diffusion coefficients of OPC concrete. As a result of evaluation about effects of exposure environments, apparent chloride diffusion coefficients of fly ash concrete are evaluated in order of tidal zone, immersion zone, and splash zone. In tidal zone, It is thought that repeated cycles of wetting and drying of sea water cause the diffusion of chloride ions rapidly.

• Magazine of the Korea Concrete Institute
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• v.14 no.2
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• pp.30-36
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• 2002

콘크리트가 화재에 노출될 경우 가열에 의한 재질의 노화 및 열팽창에 의한 열응력의 발생에 따라 주요구조부인 기둥 및 보에 큰 손상이 생기게 되어 그 내력은 크게 저하하게 된다. 철근 콘크리트 구조물의 화재 상황을 조사해 보면 (그림 1)과 같이 열응력에 의한 기둥의 전단파괴, 보의 휨파괴 및 부재의 폭열 등이 보여진다.(중략)

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.2
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• pp.1-8
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• 2022

The corrosion of reinforcement is the main reason for the performance degradation of concrete structures. The pre-rusted parts of rebar in concrete structures are vulnerable to the corrosion, especially if the structure is exposed to wet or chlorinated environments. In this study, effects of different curing solution on corrosion behavior of the pre-rusted rebars in the cement composites were investigated. HCl(3%) and CaCl₂(10%) solution were utilized to accelerate the pre-rust of the rebar, and each pre-rust condition rebar including reference (RE) were placed in mortar cylinder. Three kinds of samples then were cured in CaCl₂ (3%) solution and tap water respectively for 120 days. Electrochemical polarization and half-cell potential measurement were used to monitor the influence of curing water on the corrosion behavior of pre-rusted steel bar in cement composite. The surface morphology and composition of corroded steel bar were analyzed by scanning electron microscope and energy dispersive X-ray diffraction. The results show that the corrosion rates of pre-rusted samples in both curing water are higher than that of non-pre-rusted samples. The corrosion rates of RE, CaCl₂ and HCl pre-rusted samples in salt water were 8.14, 4.48, 13.81 times higher than those in tap water respectively, on the 120th day.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.82-92
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• 2022

This study aims to investigate the effect of total electrochemical cell resistance (TECR) on electrochemical impedance (EI) measurements of reinforced concrete (RC) by electrochemical impedance spectroscopy (EIS) using a three-electrode system. A series of experimental study is performed to measure electrochemical behavior of a steel bar embedded in a concrete cube specimen, with a side length of 200 mm, in various experimental conditions. Main variables include concrete dry conditions, coupling resistance between sensing electrodes and concrete surface, and area of the counter electrode. It is demonstrated that EI values remains stable when the compliant voltage of a measuring device is sufficiently great compared to the potential drop caused by TECR of concrete specimens. It is confirmed that the effect of the coupling resistance of TECR is far more influential than other two factors (concrete dry conditions and area of the counter electrode). The results in this study can be used as a fundamental basis for development of a surface-mount sensor for corrosion monitoring of reinforced concrete structures exposed to wet-and-dry cycles under marine environment.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.13-14
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• 2016

In the modern construction industry, since numerous skyscrapers have been built, there have been sought for developing various kinds of methods for shortening a construction period. Therefore, many kinds of studies on some kinds of cold-weather concrete have been conducted actively for the purpose of a year-round construction. Accordingly, this research team once developed a double-layered bubble sheet as a surface-coated curing material for winter. And there have been raised some worries that some initial damages to frozen concrete caused by low temperature of reinforcing bars which are exposed out of the wall areas of a wall-type apartment during winter. Therefore, in this study, it is intended to find out clearly whether it is possible for concrete to be damaged initially or not by analyzing the temperature characteristics of the exposed reinforcing bars of the wall areas under the temperature conditions during winter.