• 콘크리트학회논문집
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• 제29권3호
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• pp.299-306
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• 2017

본 연구에서는 비말대, 간만대, 침지대의 해양환경 폭로에 의한 슬래그 치환 콘크리트와 슬래그 콘크리트의 염화물 이온 침투 저항성을 검토하였다. 설계기준강도 24 MPa의 슬래그 치환 콘크리트의 슬래그 콘크리트를 제조하여, 압축강도, 주사전자현미경에 의한 미세구조의 관찰, 실내 촉진실험을 통한 비정상상태의 염화물 이동계수, 해양환경 폭로 조건에 따른 염화물 이온 침투 깊이, 탄산화 깊이를 평가하였다. 실험결과, 실내 촉진실험과는 다르게 간만대, 침지대에 폭로한 시험체의 염화물 이온 침투 깊이가 단계적으로 감소되는 것을 확인하였다. 또한, 간만대에 폭로한 시험체가 조수간만에 의한 해수의 건습작용에 의해 염화물 이온 침투 깊이가 가장 큰 것으로 나타났다. 한편, 비말대에서는 간만대와 침지대와는 다르게 고로슬래그 미분말의 치환율이 증가할수록 염화물 이온 침투 깊이가 증가하는 경향을 보였다.

• 한국구조물진단유지관리공학회 논문집
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• 제23권3호
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• pp.119-126
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• 2019

해안 지역에 시공된 철근 콘크리트 구조물은 해수 중의 염소 이온에 의해 내부 철근이 부식하게 된다. 특히 해안지역에서는 해수에 침지되는 경우뿐만 아니라 조수간만 및 비래염분의 영향을 받기 때문에 이에 대한 고려가 필수적이다. 본 연구에서는 3가지 수준의 노출 환경(침지대, 간만대, 비말대)과 노출기간 180일, 365일, 730일을 고려하여 해양환경노출실험을 실시하였다. 대상 배합은 3가지 수준의 물-결합재비 및 2가지 수준의 플라이애시 치환률(0 %, 30 %)을 고려하여 설정하였다. 모든 노출조건에서 플라이 애시 치환 배합이 OPC 배합 대비 낮은 겉보기 염화물 확산계수를 나타내었으며, 이는 플라이애시의 포졸란 반응이 원인으로 사료된다. 플라이애시 배합은 노출 기간 180일에서는 플라이애시 치환 배합이 OPC 배합 대비 최대 63 5 %의 감소율을, 노출 기간 730일 에서는 최대 55.8 %의 감소율을 나타내었다. 노출 조건에 따른 확산계수 거동을 평가한 결과, 플라이애시 치환 배합에서는 간만대, 침지대, 비말대 순으로 확산계수가 평가되었다. 간만대에서는 건습이 반복되어 염화물 이온의 침투가 빠르게 일어나는 것으로 보인다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.417-421
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• 2003

The purpose of this paper is to study on the construction of roadbed with environmental friendly soil amendment agent. The special amendment agent used in this study is mainly composed of inorganic metal salts such as sodium chloride, magnesium chloride, potassium chloride, calcium chloride,, thus is friendly to the environment, and has a function of soil-cement-agent solidification. Various components of this agent weaken the negative function of humic acid and decompose humic acid itself. Then, the calcium cation of the cement can now be made contact directly to the soil surface. The project of local road demonstration of roadbed construction with special soil treatment agent was peformed in Northeast Thailand on August 1999 by the sponsor of Highway Department of Thailand. A series of field experiments including unconfined compressive strength were carried out to investigate the physical and mechanical characteristics of solidified roadbed treated by this solidifying agent. The results of this research showed that the roadbed using poor soil could be efficiently constructed by treatment of this amendment agent.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 봄 학술발표회 논문집
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• pp.181-186
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• 1994

The steel in concrete structures under the environment of seawater easily corrode as the seawater penetrate into concrete. The purpose of this study is to analysis the properties of chloride diffusion in mortar using mineral admixtures, as a part of study to examine the chloride penetration of concrete. The results show that the chloride diffusion in mortar increased with higher water-cement ratio. In the case of mortar using mineral admixtures the scope of diffusion coefficient$(\times10^{-8}cm^2/sec)$increased SF20(0.9), SG60(3.3), FA20(3.9), and OC(6.1) in order at the same water-cement ratio 50%.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.842-845
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• 2004

When the concrete structures are in contact with seawater, concentration of chloride for estimating chloride diffusion coefficient can be defined as the chloride concentration of sea water. However, in case the concrete structures, constructed in the seashore, aren't directly in contact with seawater, it is difficult to establish the interface concentration of chloride. In addition, marine concrete structures are greatly affected by salt attack such as rebar corrosion, among the cause of salt attack, airborne sea salt is primary factor. Therefore, in this study, salt attack environment by airborne sea salt was investigated in terms of the distance from seashore at 33 spots, 6 areas in East, West, South coast for 1 year. Results indicated that airborne sea salt is decreased by $y=a{\cdot}x^{-b}$ equation to the distance from seashore.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.782-785
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• 2004

Salt attack is one of the serious deterioration factor with respect to the durability of concrete structure. Especially, in case of exposed rebar concrete structure in marine environment, corrosion of rebar is accelerated by penetration of $Cl^-$ from exterior. Through this path, volume of corroded rebar is increased about two and half times due to increased inner pressure originated from rust. As a consequence, the overall deterioration of concrete structure, namely, cracks, reduction of adhesive strength and pop-out is followed. In this paper, the effect of structure treatment of concrete on chloride resistance has been investigated. At the same time, the relationship among several characteristics, such as resistance to chloride, water absorption coefficient and surface hardness of concrete has been investigated. It is believed that surface performance improvement by the application of penetrative hardening agent influences on positively water absorption coefficient, surface hardness of concrete and resistance to chloride ion penetration.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.838-841
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• 2004

This paper presents the experimental results on the penetration of chloride. ions to ordinary portland cement concrete which is subjected to 2 different artificial environments; consecutive digestion, wetting at $3\%$ NaCl for 1 day and then drying at $40^{\circ}C$ oven for 4 days. The water-cement ratio was $35\%,\;45\%,\;55\%$. Test results showed that the intrusion depth and concentration of chloride ions penetrated into concrete in repeated wetting-drying environments were respectively deeper and higher than those of consecutive digestion environment. The penetration of chloride ions deeply depend on the effect of water to cement ratio.

• Journal of Welding and Joining
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• 제18권3호
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• pp.97-105
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• 2000

The stress corrosion cracking(SCC) and hydrogen embrittlement cracking(HEC) characteristics of a weathering steel weldment were investigated in aerated acid-chloride solution. The electrochemical properties of weldment were investigated by polarization test and galvanic corrosion test. Weathering steel did not show passive behavior in the acid-chloride solution. Galvanic corrosion between the weld metal and the base metal was not observed because the base metal was anodic to the weld metal. The slow-strain-rate tests(SSRT0 were conducted at a constant strain rate o 7.87×{TEX}$10^{-7}${/TEX}/s at corrosion potential, and at potentiostatically controlled anodic and cathodic potentials. The weldment of weathering steel was susceptible to both anodic dissolution SCC and hydrogen evolution HEC.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.433-436
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• 1999

Long-term durability of the reinforced concrete structures exposed to marine environment deteriorates seriously by the attack of the chloride ion from see water results in corrosion of steel reinforcement in concrete. Their coating effect is aluminum oxide-isocyanate-based coating material, resistance of chloride penetration, carbonation and freezing and thawing resistance were compared to acryl-based coating material and sealer type o waterproofing material. Aluminum oxide-isocyante-based and acryl-based coating material show higher resistance to chloride penetration and carbonation than the sealer type do waterproofing material and aluminum oxide-isocyanate-based coating resist about 99% of chloride penetration. Resultants to the accelerated test for freezing and thawing, coating concrete show higher resistance than non-coating concrete, respectively.

• 한국표면공학회지
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• 제32권2호
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• pp.109-124
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• 1999

A study for replacing methylene chloride for an alternative cleaning agent which can be utilized for cleaning aluminium parts of hard disk drives was carried out at Suwon factory of Samsung Electro-mechanics Co. Ltd. As a result, quite a good cleaning agent was selected through data collection of alternative cleaning agents, their analysis of environment effects and safty factors and testing of their cleaning power. As compared with methylene chloride, the selected cleaning agent has better cleaning power. It is also more environmental-friendly, less toxic and more economical. And the operating cost reduction due to adoption of this alternative cleaning agent in Samsung Electro-mechanics Co. Ltd. was more than ￦l46,000,000 annually without any capital instrument in addition to improvement of environmental and safty conditions in the plant.