• Computers and Concrete
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• 제12권1호
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• pp.91-107
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• 2013

Corrosion of RC bridge decks eventually leads to delamination, severe cracking and spalling of the concrete cover. This is a prevalent deterioration mechanism and demands for the most costly repair interventions during the service life of bridges worldwide. On the other hand, decisions for repairs are usually made whenever the extent of a limit crack width, reported in routine visual inspections, exceeds an acceptable threshold level. In this paper, while random fields are applied to account for spatial variation of governing parameters of the corrosion process, an analytical model is used to simulate the corrosion induced crack width. However when dealing with random fields, the Monte Carlo simulation is apparently an inefficient and time consuming method, hence the utility of neural networks as a surrogate in simulation is investigated and found very promising. The proposed method can be regarded as an invaluable tool in decision making concerning maintenance of bridges.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.545-548
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• 2006

This study includes the experimental investigation on the fatigue-bond behavior with respect to the various rates of steel corrosion. Major criteria of test variables are the rates of steel corrosion by chloride ion and the ratio of the applied stress to the bond failure stress. According to the test results, the slip versus number of load cycles relation was found to be approximately linear in double logarithmic scale, not only without steel corrosion but also with steel corrosion. This research will be helpful for the realistic durability design and condition assessment of reinforced concrete structures.

• Corrosion Science and Technology
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• 제8권2호
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• pp.74-80
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• 2009

The high alkaline property in the concrete pore solution protects the embedded steel in concrete from corrosion due to aggressive ions attack. However, a continuous supply of those ions, in particular, chlorides altogether with a pH fall in electrochemical reaction on the steel surface eventually depassivate the steel to corrode. To mitigate chloride-induced corrosion in concrete structures, finely grained mineral admixtures, for example, pulverized fuel ash (PFA), ground granulated blast furnace slag (GGBS) and silica fume (SF) have been often advised to replace ordinary Portland cement (OPC) partially as binder. A consistent assessment of those partial replacements has been rarely performed with respect to the resistance of each binder to corrosion, although the studies for each binder were extensively looked into in a way of measuring the corrosion rate, influence of microstructure or chemistry of chlorides ions with cement hydrations. The paper studies the behavior of steel corrosion, chloride transport, pore structure and buffering capacity of those cementitious binders. The corrosion rate of steel in mortars of OPC, 30% PFA, 60% GGBS and 10% SF respectively, with chloride in cast ranging from 0.0 to 3.0% by weight of binder was measured at 7, 28 and 150 days to determine the chloride threshold level and the rate of corrosion propagation, using the anodic polarization technique. Mercury intrusion porosimetry was also applied to cement pastes of each binder at 7 and 28 days to ensure the development of pore structure. Finally, the release rate of bound chlorides (i.e. buffering capacity) was measured at 150 days. The chloride threshold level was determined assuming that the corrosion rate is beyond 1-2 mA/$m^3$ at corrosion and the order of the level was OPC > 10% SF > 60% GGBS > 30% PFA. Mercury intrusion porosimetry showed that 10% SF paste produced the most dense pore structure, followed by 60% GGBS, 30% PFA and OPC pastes, respectively. It was found that OPC itself is beneficial in resisting to corrosion initiation, but use of pozzolanic materials as binders shows more resistance to chloride transport into concrete, thus delay the onset of corrosion.

• 한국가스학회:학술대회논문집
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• 한국가스학회 2001년도 추계학술발표회 논문집
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• pp.58-68
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• 2001

Microbiologically influenced corrosion (MIC) of carbon steel gas pipeline in soil environments was investigated at field and laboratory MIC is very severe corrosion and it is not easy to distinguish this corrosion from Inorganic corrosion because of its localized, pitting-type character Therefore, it is important to provide proper assessment techniques for the prediction, detection, monitoring and mitigation of MIC. It is possible to predict the MIC risk, i.e., the activity of sulfate-reducing bacteria (SRB) through the analysis of soil environments. Chemical, microbiological and surface analysis of corrosion products and metal attacked could reveal the possibility of the occurrence of MIC. Various electrochemical and surface analysis techniques could be used for the study of MIC. Among these techniques, thin-film electrical resistance (ER) type sensors are promising to obtain localized corrosion rate of MIC induced by SRB. It is also important to study the effect of cathodic protection (CP) on the MIC In case of coated pipeline, the relationship between coating disbondment and the activity of SRB beneath the disbanded coating is also important.

• 한국안전학회지
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• 제31권2호
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• pp.83-89
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• 2016

As the world's industrial development quickens, the highways and regional expressways have been expanding to serve the logistics and transportation needs of people. The burgeoning road construction has led to a growing interest in roadside installations. These must have reliable performance over long periods, reduced maintenance and high durability. Steel roadside barriers are prone to corrosion and other compromises to their functionality. Therefore, using high anti-corrosion steel material is now seen as a viable solution to this problem. Thus, the objective of this paper is to expand the scope of applications for high anti-corrosion steel material for roadside barriers. This paper assesses the impact safety such as structural performance, occupant protection performance and post-impact vehicular response performance by a simulation review on roadside barriers built with high strength anti-corrosion steel materials named as hot-dip zinc-aluminium-magnesium alloy-coated steel. The simulation test results for the roadside barriers built with high strength anti-corrosion steels with reduced sectional thickness meet the safety evaluation criteria, hence the proposed roadside barrier made by high strength and high anti-corrosion hot-dip zinc-aluminium-magnesium alloy-coated steel will be a good solution to serve safe impact performance as well as save maintenance cost.

• Corrosion Science and Technology
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• 제7권6호
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• pp.328-331
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• 2008

Corrosion behaviour of water intake gate steel structures with different protective measures was investigated. Five material alternatives were taken for investigation, including: imported and recycled stainless steel, carbon steel with hot zinc spraying, painting and composite coatings. Results of corrosion rate for carbon steel, SUS 304, hot zinc spray coats in three water systems of Mekong river basin (saline, blackish and fresh) were also presented. Corrosion rate of carbon steel decreased with decreasing salinity in the investigated water environments. Meanwhile, these values for zinc coated steel, behaved by another way. Environmental data for these systems were filed and discussed in relation with corrosion characteristics. Method of Life Cycle Assessment (LCA) was applied in materials selection for water intake gate construction. From point of Life Cycle Cost (LCA) the following ranking was obtained: Zinc sprayed steel < Recycled stainless steel < Composite coated steel < Painting steel < SUS 304 From investigated results, hot zinc spray coating has been applied as protective measure for steel structures of water intake systems in Mekong river basin.

• Corrosion Science and Technology
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• 제18권4호
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• pp.121-128
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• 2019

Electrochemical Impedance Spectroscopy (EIS) was used to predict corrosion behaviour of metallic Cultural Heritage assets in two monitoring campaigns: 1) an iron bar chain exposed indoor from over 500 years in the Notre Dame Cathedral in Amiens (France); and 2) a large weathering steel sculpture exposed outdoor from tens of years in Ferrara (Italy). The EIS portable instrument employed was battery operated. In situ EIS measurements on the iron chain could be used to investigate the phenomena involved in the electrochemical interfaces among various corrosion products and assess and predict their corrosion behaviour in different areas of the Cathedral. Meanwhile, the sculpture of weathering steel, like most outdoor artefacts, showed rust layers of different chemical composition and colour depending on the orientation of metal plates. The EIS monitoring campaign was carried out on different areas of the artefact surface, allowing assessment of their protective effectiveness. Results of EIS measurements evidenced how employing a simple test that could be performed in situ without damaging the artefacts surface is possible to quickly gain knowledge of the conservation state of an artefact and highlight potential danger conditions.

• 한국항공운항학회지
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• 제31권3호
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• pp.79-92
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• 2023

Aluminum alloys are important materials in modern aircraft. Aircraft failures due to corrosion are fatal and costly. Thus, information about the atmospheric corrosion of aluminum is helpful for aviation safety. This study employed four corrosion models and 12 environmental variables to improve knowledge of aluminum atmospheric corrosivity: PACER LIME, ICP, ISO CORRAG, and a modified model of CORRAG. This study applied each model on 47 aircraft operating bases in Korea and compared the results. In the results, The risk of corrosion was different for each model. The cause was the difference in environmental variables according to the model. Especially, the effect of ozone, which has recently been increasing, was shown in the results of PACER LIME. These findings suggest that caution is needed when assessing atmospheric corrosion risk as a single model. Furthermore, it means that the application and integration of various models are needed to improve atmospheric corrosion risk assessment.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 추계학술대회 논문집
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• pp.111-112
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• 2007

• 공업화학
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• 제20권2호
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• pp.177-185
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• 2009

자동차용 써모스타트 하우징 피팅부상의 침전물(스케일)에 대한 고장분석을 실시하였다. 에너지분산형분석기와 전자현미분석기를 이용하여 침전물이 부동액의 주요 첨가제 성분임을 확인하였다. 자세한 유기성분 분석을 위해 열분해 기체크로마토그래피/질량분석을 수행한 결과, 침전물의 주성분이 벤조산이며, 소량의 아세토페논, 벤젠 및 페닐계 화합물 등으로 이루어져 있음을 확인하였다. 더불어 침전물 생성 원인은 알루미늄 하우징과 고무호스 사이에 존재하는 틈새 공간에 부동액 성분의 침전에 따른 틈새부식에 기인한 것으로 판단된다. 이런 결과를 바탕으로 하여 써모스타트 하우징상의 침전물 생성과 틈새부식을 재현할 수 있는 가속시험기법을 개발하였다. 가속인자(온도, 습도)를 변화시키면서 실제 가동조건을 묘사하였다. 가속시험에서 얻은 침전물을 성분 분석을 통해 완벽히 재현되었음을 확인하였다.