• Structural Engineering and Mechanics
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• 제65권2호
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• pp.191-201
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• 2018

The corrosion environments in a steel structure are significantly different depending on the individual parts of the members. To ensure the safety of weathering steel structures, it is important to evaluate the time-dependent corrosion behavior. Thus, the progress and effect of corrosion damage on weathering steel members should be evaluated; however, the predicted corrosion depth, which is affected by the corrosion environment, has not been sufficiently considered until now. In this study, the time-dependent thicknesses of the corrosion product layer were examined to quantifiably investigate and determine the corrosion depth of the corroded surface according to the exposure periods and corrosion environments. Thus, their atmospheric exposure tests were carried out for 4 years under different corrosion environments. The relationship between the thickness of the corrosion product layers and mean corrosion depth was examined based on the corrosion environment. Thus, the micro corrosion environments on the skyward and groundward surfaces of the specimens were monitored using atmospheric corrosion monitor sensors. In addition, the evaluated mean corrosion depth was calculated based on the thickness of the corrosion product layer in an atmospheric corrosion environment, and was verified through a comparison with the measured mean corrosion depth.

• 상하수도학회지
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• 제21권6호
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• pp.689-699
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• 2007

The accurate estimation of water pipe deterioration is indispensable to prevent pipe breakage and manage in advance. In this study, corrosion of water pipe is adopted, which is relatively underestimated although it takes most part of deteriorating pipeline. Predicting corrosion rate and corrosion depth of a pipe can make an increase the life span of the pipeline, which is laid under the ground according to characteristics of soil and water corrosion. For the purpose, mathematical models that can presume nominal depth through estimation of pit corrosion and corrosion rate is introduced. As comparison of results with conventional methods in other foreign countries, it is evaluated that the external corrosion depth is estimated less than the models, proposed by other researchers and the internal corrosion rate was processed faster than the external corrosion rate.

• Corrosion Science and Technology
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• 제11권5호
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• pp.157-164
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• 2012

In first experiment series, this paper is devoted for examining progress of reinforcement corrosion due to carbonation in concrete and to quantify uncarbonation depth to protect reinforcement from corroding. The tolerance of cover depth should be considered in order to prevent carbonation-induced corrosion. From the relationship between the weight loss of reinforcement and corrosion current density for a given time, therefore, the tolerance of cover depth to prevent carbonation-induced corrosion is computed. It is observed that corrosion occurs when the distance between carbonation front and reinforcement surface (uncarbonated depth) is smaller than 5 mm.As a secondary purpose of this study, it is investigated to examine the interaction between carbonation and chloride penetration and their effects on concrete. This was examined experimentally under various boundary conditions. For concrete under the double condition, the risk of deterioration due to carbonation was not severe. However, it was found that the carbonation of concrete could significantly accelerate chloride penetration. As a result, chloride penetration in combination with carbonation is a serious cause of deterioration of concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2010년도 춘계 학술논문 발표대회 1부
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• pp.229-230
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• 2010

The Carbonation, one of the main deterioration factors of concrete, reduces capacity of members with providing rebar corrosion environment. Consequently it suggested standards of all countries of world, carbonation depth prediction equation of respective researchers and time to rebar corrosion initiation. As a result of carbonation depth prediction equation calculation, difference of time to rebar corrosion initiation is 149 years and difference of carbonation depth prediction equation is 162 years when water cement ratio is 50%. So a study on rebar corrosion with carbonation depth will need existing reliable data and verifications by experiment.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.345-350
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• 2001

Reinforced concrete is, in general, known as a high durability material due to a strong alkalinity of cement. Probable concrete cracks could incur steel corrosion of RC structures and then could easily deteriorate the concrete durability, which can be fully secured by a systematic quality control for the construction of concrete structures. For the corrosion protection of reinforcing steels in concrete, however, current design specifications of concrete cover depth do not in-depth consider the effect of the cracks as well as the chloride content of RC structures. Therefore, appropriate provisions for concrete cover depth should be coded by considering the influence of concrete cracks on the corrosion of reinforcing steels. The objective of this research is to investigate pertinent cover depth, which can prohibit rebar corrosion, on the basis of experimental corrosion measurements of reinforcing steels on crack characteristics such as the width, depth and frequency of concrete cracks.

• Steel and Composite Structures
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• 제24권6호
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• pp.753-765
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• 2017

This paper aims to investigate the strength degradation of reinforced concrete piers wrapped with steel plates which corrode at the pier base by employing a three dimensional elasto-plastic finite element formulation. The prediction accuracy of the employed finite element analysis method is firstly verified by comparing the analytical results with test results. Then, a series of parametric studies is carried out to investigate the effects of steel plate's corrosion position along width direction, corrosion depth along plate thickness, corrosion range along width direction, and steel plate-concrete bonding degradation on the strength of the piers. It is observed that the strength degradation of the piers is closely related to steel plate's corrosion position, corrosion depth and corrosion range in the case of local corrosion on the webs. In contrast, when the base of flanges corrodes, the strength degradation of the piers is only related to steel plate's corrosion depth and corrosion range, and the influence of corrosion position on the strength degradation is very gentle. Furthermore, the strength of the piers decreases with the degradation of steel plate-concrete bonding behavior. Finally, the maximum strength of the piers obtained from numerical analysis corresponding to different bonding behavior is compared with theoretical results within an accepted error.

• 한국구조물진단유지관리공학회 논문집
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• 제13권5호통권57호
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• pp.160-168
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• 2009

철근이 부식되면 오염된 콘크리트를 제거하고 철근방식을 하고 보수하는 방법과 방청제를 도포하는 방법으로는 철근위치에서 방청성능을 확보하기가 곤란한 실정이다. 이에 본 연구에서는 철근위치까지 방청제를 고압 침투시키기 위한 연구개발에 앞서 방청제 가압 침투 실험을 통하여 침투깊이를 측정하고 위치별 아질산이온의 양을 측정하여 물시멘트비, 압력, 가압시간에 따른 침투깊이 예측하고 우수한 방청성을 가지는 염화물이온과 아질산이온의 몰비 0.6 이상이 되는 물시멘트비와 압력, 가압시간을 산정하였다. 실험결과 물시멘트비가 방청제의 침투에 가장 큰 영향을 주며 또한 실험체의 깊이가 깊어질수록 침투시킨 방청제의 농도는 같지 않고 낮아지는 것을 알 수 있었다.

• 한국건설순환자원학회논문집
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• 제11권3호
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• pp.184-191
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• 2023

철근 콘크리트 구조물은 부식이 증가함에 따라 부식생성물로 인한 균열이 발생하고 하중저항 능력이 감소한다. 본 연구에서는 140시간 동안 촉진염해시험(ICM)을 적용하여 부식을 유도하였으며 부식 전후의 초음파속도 변화, 휨파괴 하중, 부식생성물량을 평가하였다. 피복두께를 3수준(20 mm, 30 mm. 40 mm)으로 고려하였는데, 피복두께가 증가할수록 균열발생시기 및 부식생성량이 증가하였다. 또한 초음파 속도는 피복두께의 감소 및 부식생성량의 증가에 따라 뚜렷한 선형관계를 가지고 감소하였다. 휨파괴 하중의 경우 부식에 따라 10 % 이상 휨하중이 감소하였으나, 명확한 상관성을 도출할 수 없었는데, 이는 부식률이 작으므로 철근단면적의 감소 영향보다 슬립에 의한 영향이 크기 때문이다. 피복두께가 증가함에 따라 부식생성량 및 초음파 속도는 뚜렷한 선형관계를 가지고 변화하였으며, 부식으로 인한 균열발생 시간은 평가된 전류의 기울기를 분석하여 추측할 수 있었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2010년도 춘계 학술논문 발표대회 1부
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• pp.5-7
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• 2010

Corrosion sensors were devised to develop a system whereby the depth of chloride permeation from concrete surfaces can be monitored in cover concrete of reinforced concrete structures. For making sensor which is similar to rebar author uses Screen printer machines, Ag paste and Fe powder. Appropriate portion of Ag and Fe is over 1:2. The resistance of sensors increased as the degree of corrosion increased. And according to cover depth author suggests sensor system which has a demanded cover depth. It was therefore confirmed that the corrosion sensor can monitor chloride permeation by change of resistance.

• 한국기계가공학회지
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• 제16권1호
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• pp.83-89
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• 2017

The corrosion of metal specimens was analyzed in this study using laser-induced breakdown spectroscopy. The samples used in the study were magnesium alloys and corrosion, and standard specimens were prepared and analyzed using surface and depth analysis. The spectral wavelengths used in the oxide layer analysis were 777.196 nm, 777.421 nm, and 777.543 nm. The spectral line of the surface corrosion was confirmed by experimentation, and surface micro morphology analysis was performed using an optical microscope. Approximately $100{\mu}m$ corrosion depth was confirmed via laser irradiation in the depth direction. The results of laser-induced breakdown spectroscopy and the SEM-EDS analysis were compared and analyzed.