• Journal of Advanced Marine Engineering and Technology
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• 제19권3호
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• pp.62-69
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• 1995

In order to investigate the effect of TiN coating on corrosion fatigue behavior of metal, the rotary bending corrosion fatigue tests were carried out in 3% NaCl solution by using the round bar specimens of high-speed steel, SKH-9, coated with TiN by PVD method. From the experimental results, fatigue strength of TiN coating steel in air was obvious improvement as compared with that of the substrate because of the restriction of dislocation movement in near surface of the substrate by hard thin film. In 3% NaCl solution, corrosion fatigue life of TiN coating specimen in high stress level was improvement same as in air. But in low stress level, corrosion fatigue life of TiN coating one was equivalent to that without coating, due to much crack initiated from corrosion pits formed at the substrate by failure of coating layer.

• Advances in concrete construction
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• 제7권4호
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• pp.203-210
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• 2019

Concrete structures in marine environment are susceptible to chloride attack, where chloride diffusion results in the corrosion of steel bar and further lead to the cracking of concrete cover. This process causes structural deterioration and affects the response of concrete structures to different forms of loading. This paper presents the use of ABAQUS Finite Element Software in simulating the processes involved in concrete's structural degradation from chloride diffusion to steel corrosion and concrete cover cracking. Fick's law was used for the chloride diffusion, while the mass loss from steel corrosion was obtained using Faraday's law. Pressure generated by steel corrosion product at the concrete-steel interface was modeled by applying uniform radial displacements, while concrete smeared cracking alongside the Extended Finite Element Method (XFEM) was used for concrete cover cracking simulation. Results show that, chloride concentration decreases with penetration depth, but increases with exposure time at the concrete-steel interface. Cracks initiate and propagate in the concrete cover as pressure caused by the steel corrosion product increases. Furthermore, the crack width increases with the exposure time on the surface of the concrete.

• Structural Engineering and Mechanics
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• 제17권6호
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• pp.863-878
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• 2004

Steel corrosion in reinforced concrete structures leads to concrete cover cracking, reduction of bond strength, and reduction of steel cross section. Among theses consequences mentioned, reduction of bond strength between reinforcement and concrete is of great importance to study the behaviour of RC members with corroded reinforcement. In this paper, firstly, an analytical model based on smeared cracking and average stress-strain relationship of concrete in tension is proposed to evaluate the maximum bursting pressure development in the cover concrete for noncorroded bar. Secondly, the internal pressure caused by the expansion of the corrosion products is evaluated by treating the cracked concrete as an orthotropic material. Finally, bond strength for corroded reinforcing bar is calculated and compared with test results.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 봄 학술발표회 논문집
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• pp.148-151
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• 1994

Up to now, sea sand without complete removal of salt is being used in the construction works because there is little satisfactory counterplan for the substitute aggregate. In the case that such sea sand is used in the reinforced concrete, the residual salt gives rise to deterioration phenmenon and iron corrosion, reducing durability of the ferro-concrete structures. The paper, an experimental study on the effect of corrosion protection by tighting concrete used SF and FA, is to investigate general steel bar's corrosion and to develop concrete using sea sand economically after it is analyzed and examinated ratio of the corrosion area affected by the autoclave cycle. As a test results, as for corrosion area ratio, it is very effective to use admixrutes such as SF and FA which decrease corrosion area remarkably with increasing the amounts of admixtures. Accordingly the use of admixtures is advantageous for tightening concrete and has an effect of salt damage prevention and rust protection in concrete used sea sand.

• 한국건설순환자원학회논문집
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• 제6권1호
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• pp.59-65
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• 2018

콘크리트 구조물은 다양한 환경에 노출되며, 부식환경인 해안가에서는 매립 보강재의 부식저항성 및 동결융해 저항성이 함께 평가되어야 한다. 최근 개발된 FRP Hybrid Bar는 내부에 강재가 있으며 유리섬유와 에폭시가 코팅된 보강재인데, 기존 FRP Bar보다 탄성계수가 높은 장점이 있다. 본 연구에서는 FRP Hybrid Bar에 대하여 동결융해 300 cycle 시험을 수행한 뒤, 내부식특성과 중량결손율, 및 부착특성을 평가하였다. 300 cycle 이후 2번 에폭시를 코팅한 경우에 규사의 손실이 가장 적었으며, 외관의 결함이 관측되지 않았다. 부착강도는 규사코팅에 따른 조도의 증가로 FRP Hybrid Bar의 경우 일반철근의 120 % 수준을 나타내었다. 또한 일반철근을 가진 시편의 부착력은 부식시간 3일에서는 0.86 ~ 0.89 배, 5일에서는 0.35~0.38 배로 크게 감소하였으나, 동결융해 전후의 FRP Hybrid Bar를 가진 콘크리트 공시체는 부착강도의 감소가 발생하지 않았다.

• Corrosion Science and Technology
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• 제8권4호
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• pp.157-161
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• 2009

The corrosion resistance of reinforcing bar was studied to endure the marine environment during shipment. The red rust on the surface did not damage the adherence in the concrete structures, especially in highly alkaline environment, but made the consumer doubt of the quality. The passivation process by alkalization of the quenching water in the tempcore process failed to endure the long shipping period. The ceramic coating by sol-gel process improved the corrosion resistance without damaging the mechanical properties and adherence between concrete and reinfiorcing bar. Optimal concentration of the coating solution and coating temperature were tested. No additional energy was necessary for the coating process by spraying during cooling process, resulting simplified process and low cost. Salt spray test, cyclic corrosion test and atmospheric test were employed to confirm the resistance. The corrosion rates were presented by rating number and polarization resistance. The coating layer was examined by FIB, XRD and SEM etc.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1992년도 가을 학술발표회 논문집
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• pp.31-36
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• 1992

This paper, an experimental study on the effect of mixed sand used sea and river as fine aggregate of concrete, is connected with the properties of fresh and hardended concrete and steel corrosion to investigate workability and engineering properties and general steel bar's corrosion of concrete used mixed sand. After analyzing positively fresh and hardenend concrete and ratio of the corrosion area affected by the autoclave cycle, the purpose of this paper is to provide an experimental data developing concrete used mixed sand.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.127-132
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• 1996

Recently in the country a corrosion of steel is accelerated due to using of sea sand including salts, and critical problem on the durability of concrete structure is occured. Thus a control of steel corrosion is very important in the stability of structure. Coated steel is in use with a method of steps of steel corrosion in U.S,A. Japan etc, and as well in domestic case the manufactured coating steel of three types is on the market. Those are Epoxy coated steel, Zinc-strength, concrete specimen size, bar diameter, which can affect bond characteristics between steel and concrete in order to know their relative bond characteristics.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 추계 학술논문 발표대회
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• pp.106-107
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• 2013

The purpose of this study is to characterize the bonding properties between reinforced bar and re-emulsion polymer cement mortar through the pull off test. The properties of polymer cement mortar before and after hardening were measured. Spiral reinforced steel bar was used to control the brittleness fracture of test specimens. In addition polymer content as experimental factors, the types of reinforced bar and corrosion were considered as well. Non linear FEM analysis was carried out to expect the behavior of bonding interface under the certain load.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.237-240
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• 2006

The corrosion of steel reinforcing bar has been the major cause of the reinforced concrete deterioration. GFRP(Glass Fiber-Reinforced Polymer) reinforcing bar has emerged as one of the most promising and affordable solutions to the corrosion problems of steel reinforcement in structural concrete. However, GFRP rebar is prone to deteriorate due to other degradation mechanisms than those for steel. The high alkalinity of concrete, for instance, is a possible degradation source. This paper presents the long-term deterioration of the GFRP rebar under alkali environmental condition.