• 자원환경지질
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• 제26권3호
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• pp.421-429
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• 1993

Dissolution reactions of chemical grade zinc sulfide and natural sphalerite were studied in ferric chloride solution as an oxidant. To enhance the leaching reaction, ultrasonic technique was employed in this investigation. For the reaction with pure zinc sulfide, chemical reaction was the rate limiting step in the range of low conversion irrespective of applying ultrasonic wave. And the diffusion through liquid film instead of diffusion through product layer of free sulfur was the rate determining step because ultrasonic vibration removes the product from reaction zone. In the case of sphalerite with the ultrasonic vibrator, it was found that inert mineral layer diffusion was the rate determining step, in which the elemental sulfurs formed were removed by the ultrasonic action. Experimental results showed that the ultrasonic technique proved to be the methods which can significants improve the leaching performance.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.196-199
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• 2004

Metakaolin is a cementitious material for producing high-strength concrete. This material is now used as substitute for silica-fume. In this paper, we tested the compressive strength of concrete according to the substitute ratio of metakaolin, silica-fume. And we did the durability test such as chloride ion diffusion and chemical attack. In the compressive strength test, the result shows that $10\%$ substitute of metakaolin & silica-fume for binder is optimum. In the chloride ion diffusion test, according to the increase of substitute of metakaolin & silica-fume for binder, the diffusion coefficient is more reduced. And in the chemical attack test, according to the increase of substitute, the resistance is more excellent. In the durability test, we recognized that metakaolin is able to used as a substitute for silica-fume.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2011년도 정기 학술대회
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• pp.404-405
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• 2011

원전구조물의 방사성 폐기물 처분시설의 경우 지하수에 해수가 유입되어 콘크리트에 염소이온 침투가 발생할 수 있으며, 콘크리트 내부에 존재하는 인장철근의 부식에 의한 내구성 저하 및 수명 단축이 주된 문제가 된다. 본 논문에서는 원전콘크리트 구조물에서의 확산에 의한 염소이온 침투에 대한 수학적 모델을 제시하였다. 콘크리트 중의 염소이온의 침투는 콘크리트의 노출환경, 습윤상태에 따라 확산(Diffusion), 대류(Absorption), 전기적 이동(Migration)에 의해 발생한다. 이러한 조건을 모두 고려하여 제시한 방정식에 의해 염소이온의 침투를 예측할 수 있다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.201-206
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• 1996

Recently, to utilize conutry effectively, many concrete structures such as Young Jong Do New Airport. SeoHae Bridege are being constructed. Therefore, Corrosion of steel reinforcement of concrete structures become more and more serious, and prediction of service lives of concrete structures considering steel corrosion is needed much more. The methodologies of predicting service life have been studied for various views, but mathematical modelling based on diffusion theory is generally applied. The purpose of this paper is to investigate current mathematical models, and suggest theoretical basis on estimation of service lives of concrete structures in marine environment. Thus, the procedures for selecting variables such as threshold chloride concentration, diffusion coefficient, etc are suggested, and the service lives calculated through these procedures for various diffusion coefficients and cover depths are presented.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.217-220
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• 2004

Metakaolin is a cementitious material for producing high-strength concrete. This material is now used as substitute for silica-fume. In this paper, we did the durability test such as chloride ion diffusion, chemical attack. repeated freezing and thawing, carbonation. In the chloride ion diffusion test, according to the increase of substitute of metakaolin & silica-fume for binder, the diffusion coefficient is more reduced. And in the chemical attack test, according to the increase of substitute, the resistance is more excellent. In the other durability test, the concrete using metakaolin is also compared with those of the portland cement concrete and silica fume concrete. According to these tests, we recognized that metakaolin is able to be used as a substitute for silica-fume.

• 한국구조물진단유지관리공학회 논문집
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• 제17권1호
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• pp.64-75
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• 2013

실내촉진실험과 동시에 현장폭로실험을 병행하였기 때문에 연차별 실험계획에 따라 최근 5년차의 현장실험체 분석을 수행하고 모델을 업그레이드하는 과정에서 모델 검증을 위해 준공된 지 30년 가량된 방조제의 배수갑문콘크리트의 염화물 침투프로파일을 분석하였다. Zhang의 연구결과에서 언급된 표면에 가까운 콘크리트내부 염화물 농도를 기본모델의 표면염화물농도 대신으로 적용하였다. 장기간 노출되는 실험체의 염화물 측정자료 분석에서 확산계수의 변화분석을 통하여 Maage의 제안식을 기본모델에 적용하였다. 이렇게 보완된 수정모델을 통하여 예측된 자료와 현장자료를 비교하고, 임계시점, 즉 보수시점을 도출함으로서 본 연구의 제안모델과 유지보수 시스템이 간만대 염화물 침투프로파일 추정과 적정보수 시점 및 비용 예측에 사용될 수 있음을 보였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.269-274
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• 1997

Recently, premature reinforcement corrosion in concrete structures exposed to chloride containing environments has an important problem. This is due to an increasing use of marine aggregate of chloride containing admixture a the mixing stage and due to an increase of concrete construction in marine environments. In this study, the behavior of chloride ions introduced into concrete from concrete surface by a marine environment was modeled. The physicochemcial processes including the diffusion of chloride ion in aqueous phase of pores, the adsorption and desorption of chloride ions to and from the surface of solid phase of concrete, and the chemical reaction of chloride ion with solid phase were analyzed by using the finite element method. The results of this study may be used to predict the onset of reinforcement corrosion, and identify the maximum limit of chloride ions contained in admixtures.

• 한국건설순환자원학회논문집
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• 제7권2호
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• pp.109-115
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• 2019

콘크리트에 균열이 발생하는 경우 균열부로의 열화 이온의 침투가 확산되어 철근콘크리트 구조물에 구조적 내구적 문제를 야기한다. 본 연구에서는 보통 및 고강도 플라이애시 콘크리트를 대상으로 재령 56일에 최대 1.0mm까지 다양한 균열 폭을 유도한 후 재령 2년의 정상상태 촉진 염화물 확산계수를 평가하였다. 균열 효과를 선형회귀분석을 통해 고려하면 고강도 콘크리트는 보통 강도 콘크리트 보다 균열 폭에 의한 확산계수 증가가 다소 적었으며 균열 폭이 증가함에 따라 확산계수가 비선형적으로 증가하였다. 또한 두 가지 배합에서 재령이 증가할수록 균열에 의한 영향이 감소하였다. 지수함수 형태를 사용하여 균열 및 재령 효과를 정량화하는 경우, 선형회귀분석을 통한 경우보다 더 높은 결정계수를 나타내었다. 정상상태에서는 균열 효과와 재령의 영향 간의 상관성이 크지 않은 것으로 보이며 두 가지 독립영향을 고려하는 경우 합리적인 균열부 콘크리트 확산성 예측식을 제안할 수 있다고 사료된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.997-1002
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• 2001

There are two types of chloride in concrete; one is added as concrete materials' chloride when concrete's mixing, and .the other is penetrated from the air and sea water in the sea-shore area. These chlorides penetrate into concrete, and they are accumulated inside the concrete with aging. This study aimed to evaluate the chloride ion penetration resistance of concrete containing GGBFS in the sea-shore area. Therefore, the specimens made with the replacement ratios(0, 0.30, 0.45, 0.60) of GGBFS were put into 3% NaCl solution according to the chloride accelerating test of JCI-SC3, and then investigated the weight changes, compressive strength, chloride ion with the depths of the specimens by aging. The result is that the diffusion coefficient of chloride ion is decreased with the increase of replacement ratios when compared to OPC

• Architectural research
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• 제20권1호
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• pp.27-34
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• 2018

To improve the chloride ingress resistance of concrete, slag is widely used as a mineral admixture in concrete industry. And currently, most of experimental investigations about non steady state diffusion tests of chloride penetration are started after four weeks standard curing of concrete. For slag blended concrete, during submerged chloride penetration tests periods, binder reaction proceeds continuously, and chloride diffusivity decreases. However, so far the dependence of chloride ingress on curing ages are not detailed considered. To address this disadvantage, this paper shows a numerical procedure to analyze simultaneously binder hydration reactions and chloride ion penetration process. First, using a slag blended cement hydration model, degree of reactions of binders, combined water, and capillary porosity of hardening blended concrete are determined. Second, the dependences of chloride diffusivity on capillary porosity of slag blended concrete are clarified. Third, by considering time dependent chloride diffusivity and surface chloride content, chloride penetration profiles in hardening concrete are calculated. The proposed prediction model is verified through chloride immersion penetration test results of concrete with different water to binder ratios and slag contents.