• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.1193-1198
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• 2001

The glass of Ground Granulated Blast Furnace Slag(GGBFS) was released by the hydroxyl ions during the hydration of the Portland cement. That results in relatively less $Ca(OH)_{2}$ in the concrete replaced with GGBFS than in ordinary portland cement concrete(OPCC). As the quantity of $Ca(OH)_{2}$ is decreased, the rate of carbonation in the concrete replaced GGBFS is faster than OPCC. Therefore, it has been misunderstood that the concrete replaced GGBFS has negative effect on the corrosion of steel by carbonation. Therefore, this study aimed at the relation between carbonation and rebar corrsion in the concrete with GGBFS, measuring air.water permeability, half cell, and corrosion rate by the depth of carbonation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.789-792
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• 1999

Reinforced concrete structures covered creek for road vehicle located in urban areas have been experiencing corrosion of concrete and reinforcing steel caused by $H_2S$ gases generated by anaerobic bacterial. H2S gases react with oxygen and water to form sulfuric acid ($H_2SO_4$). This acid chemically attacks concrete, and sulfate ions penetrate into the concrete, causing rebar corrosion. In this work, to determine the conditions of RC culvert boxes which were constructed in the 1970s, various tests were conducted, including carbonation depth, compressive strength, half-cell potential measurements, and XRD analyses. Results indicated that the concrete deterioration was caused by sulfate attack and rebar corrosion. This paper discusses the evaluation on the durability of reinforced concrete structures covered creek for road vehicle.

• 전기화학회지
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• 제3권1호
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• pp.31-38
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• 2000

전기화학적 염소 추출법에 의해 염분이 함유된 시멘트 모르터내의 철근의 방식효과를 고찰하였다 초기에 혼입된 염 중 약 $43\%$가 Friedel 염 형태로 시멘트 모르터내에 고정되었으며, 전기화학적 염소추출법에 의해 가용성 염소이온의 추출이 가능하였다. Fick's 2nd law에 의해 시간 및 거리에 따른 농도 profile의 예측이 가능하였으며, 이는 실제값에 근접하였다. 전기화학적 염소추출법 수행 후 부식전위는 양의 방향으로 상승하였으며, 교류 임피던스결과 부식이 억제됨을 알 수 있었다.

• Computers and Concrete
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• 제4권4호
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• pp.285-298
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• 2007

Corrosion of Reinforcement (rebar) is nondestructively estimated by the half-cell potential measurement. As is the case with other nondestructive testings (NDT), understanding of the underlying principles should be clarified in order to obtain meaningful results. Therefore, the measurement of potentials in concrete is analytically investigated. The effect of internal defects on the potentials measured is clarified numerically by the boundary element method (BEM). Thus, a simplified inversion by BEM is applied to convert the potentials on concrete surface to those on rebars, taking into account the concrete resistivity. Because the potentials measured on concrete surface are so sensitive to moisture content, concrete resistivity and surface condition, an inverse procedure to convert the potentials on concrete surface into those on rebars is developed on the basis of BEM. It is found that ASTM criterion is practically applicable to estimate corrosion from the potential values converted. In experiments, an applicability of the procedure is examined by accelerated corrosion tests of reinforced concrete (RC) slabs. For practical use, the procedure is developed where results of IBEM are visualized by VRML (Virtual Reality modeling Language) in three-dimensional space.

• Structural Engineering and Mechanics
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• 제61권6호
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• pp.693-700
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• 2017

Concrete cover cracking due to the corrosion of steel reinforcing bars is one of the main causes of deterioration in Reinforced Concrete (RC) structures. The oxidation level of the bars causes varying levels of expansion. The rebar expansions could lead to through-thickness cracking of the concrete cover, where depending on the cracking characteristics, the service life of the structures would be affected. In this paper, the effect of geometrical and material parameters, i.e., concrete cover thickness, reinforcing bar diameter, and concrete tensile strength, on the required pressure for concrete cover cracking due to corrosion has been investigated through detailed numerical simulations. ABAQUS finite element software is employed as a modeling platform where the concrete cracking is simulated by means of eXtended Finite Element Method (XFEM). The accuracy of the numerical simulations is verified by comparing the numerical results with experimental data obtained from the literature. Using a previously proposed empirical equation and the numerical model, the time from corrosion initiation to the cover cracking is predicted and then compared to the respective experimental data. Finally, a parametric study is undertaken to determine the optimum ratio of the rebar diameter to the reinforcing bars spacing in order to avoid concrete cover delamination.

• 한국산학기술학회논문지
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• 제16권10호
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• pp.6551-6557
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• 2015

철근부식에 의해 발생된 녹은 철근 주변의 콘크리트에 팽창 압력을 유발하여 콘크리트의 균열, 피복콘크리트의 박리나 탈락, 철근의 단면적 감소 등 구조물의 내구성에 부정적인 영향을 끼친다. 본 논문에서는 코일철근을 대상으로 3차원 스캐너를 이용하여 철근이 부식됨에 따른 표면적을 측정하여 철근의 부식률과 표면 거칠기와의 관계를 프랙탈 이론을 이용하여 규명하였다. 코일 철근은 현장 적재일이 길수록 부식률이 증가하였으며, 부식률이 증가할수록 표면 거칠기는 거칠게 평가되었다. 프랙탈 차원의 증가량은 적재일 3일, 7일, 14일, 21일 경우 각각 0.0235, 0.0280, 0.0319, 그리고 0.0455로 나타났다. 이때의 부식률은 각각 0.3367%, 0.6127%, 0.7898%, 그리고 1.1965%로 나타나 프랙탈 차원을 이용한 부식된 코일철근의 표면 물리량 평가는 실제 부식률과 유사한 결과를 나타냈다.

• Corrosion Science and Technology
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• 제13권6호
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• pp.214-223
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• 2014

Interest in the durability assessment and structural performance has increased according to an increase of concrete structures in salt damage environment recent years. Reliable way ensuring the most accelerated corrosion test is a method of performing the rebar corrosion monitoring as exposed directly to the marine test site exposure. However, long-term exposure test has a disadvantage because of a long period of time. Therefore, many studies on reinforced concrete in salt damage environments have been developed as alternatives to replace this. However, accelerated corrosion test is appropriate to evaluate the critical chlorine concentration in the short term, but only accelerated test method, is not easy to get correct answer. Accuracy of correlation acceleration test depends on the period of the degree of exposure environments. Therefore, in this study, depending on the concrete mix material, by the test was performed on the basis of the composite degradation of the salt damage, and investigate the difference of corrosion initiation time of the rebar, and indoor corrosion time of the structure, of the marine environment of the actual environments were inuestigated. The correlation coefficient was derived in the experiment. Long-term exposure test was actually conducted in consideration of the exposure conditions submerged zone, splash zone and tidal zone. The accelerated corrosion tests were carried out by immersion conditions, and by the combined deterioration due to the carbonation and accelerated corrosion due to wet and dry condition.

• 한국건축시공학회지
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• 제19권6호
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• pp.511-520
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• 2019

혼화재 혼입에 따른 콘크리트의 철근부식 임계염화물량의 변화를 실험적으로 평가하였다. 콘크리트 배합조건은 OPC 100%, OPC 70% + GGBFS 30%, OPC 40% + GGBFS 60%, OPC 40% + GGBFS 40% + FA 20% 로 구분하여 4가지 배합의 철근 콘크리트 시험체를 제작하였다. 시험체에 NaCl 수용액을 공급하며, 매립된 철근의 자연전위를 모니터링 하였다. 부식이 발생한 것으로 판단된 시험체는 NaCl 수용액 공급면으로부터 5mm간격으로 절단하여 염소이온량 프로파일을 실시하였다. 콘크리트에 매립된 철근의 부식 개시시기는 시멘트를 혼화재로 치환하여 사용하는 경우 지연되는 것을 확인하였다. 하지만 콘크리트에 매립된 철근의 부식임계염화물량은 혼화재 혼입율 증가에 따라 감소하여, OPC 1.46kg/㎥, S30 0.98kg/㎥, TBC 0.74kg/㎥, S60 0.71kg/㎥ 순으로 높게 나타났다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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• pp.229-232
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• 1998

Recently it has become general to use the inhibitor with a view to protecting corrosion of rebars in concrete. As the inhibitors used in construction works are almost made in America or Japan, we immediately need to begin home production of inhibitors. In this paper, to estimate the domestic anodic inhibitor of nitrite in comparison with foreign made inhibitor we made some fundamental experiments of setting time, slump and compressive strength. Besides, we analysed the effect of corrosion protection of inhibitor on the ground of corrosion current, resistance to chloride penetration and diffusion of chloride ingress in concrete.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2000년도 춘계총회 및 학술발표회
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• pp.22-22
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• 2000