• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.483-486
• /
• 2005

This study investigates the effect of air contents on concrete properties, compressive strength, chloride migration coefficient and freeze-thaw resistance. Chloride migration and freeze-thawing test conducted in accordance with NT-BUILD 492 and pr-EN 12390-9, respectively. As a result, compressive strength reduced with air contents increase, but chloride migration coefficient more influenced by the water-binder ratios than air contents. Air contents of hardened concrete measured half times that of fresh concrete after mixing. Also, concrete scaling decreased with air contents increased.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.11a
• /
• pp.120-123
• /
• 2003

In order to evaluate the applicability of steel slag aggregates for tetrapod concrete, the properties of concrete as structural material were investigated. The biochemical research of marine concrete using steel slag aggregates was also carried out. The tested concrete properties are slump, air content, compressive strength, splitting tensile strength, elastic modulus, carbonation, hydration heat, freezing and thawing, sulfate attack, drying shrinkage, etc. The biochemical experiments are carried to research the propagation and reproduction of seaweeds and survival of bottom dwelling species. According to the experimental results, the steel slag aggregate content did not have a significant effect on compressive strength, splitting tensile strength and elastic modulus. The durability of concrete was not influenced by the steel slag aggregate content. From the biochemical research, steel slag aggregate can be evaluated as the material that is ideally suited for promoting propagation and reproduction of seaweeds and survival of bottom dwelling species.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.04a
• /
• pp.827-832
• /
• 2000

Bridge structure is known as one of important infrafacilities for comfortable human life. Recent long-span bridges, such as Kwang-Ahn Grand bridge, Seo-hae Grand Bridge, Young-Jong Grand Bridge, etc, have been designed and constructed near the seaside without in-depth consideration of concrete durability problem. It is in particular noted tat corrosion of reinforcement steel in concrete is very important for the durability enhancement of concrete structures. The objective of this experimental study is to investigate the corrosion behavior of reinforcing steels in concrete specimens which are exposed to cyclic wet and dry saltwaters, and then to develop pertinent corrosion protection system such as rational cover depth, corrosion inhibitors, cathodic system for reinforced bridges exposed to marine environment.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1996.10a
• /
• pp.201-206
• /
• 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.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1996.10a
• /
• pp.196-200
• /
• 1996

In the case of construction under the marine environment the durability of concrete structures is everely deteriorated by the penetration of salts which results in the corrosion of reinforcing steel. To verify the effect of corrosion protection of reinforcing steel by isolating the penetration of chlorideion this study investigated the bond strength between painting material and concrete, the degree of the penetration-diffusion of chloride ion and the accelerated corrosion test using different potential. Results show that the painted concrete has little the penetration-diffusion of cholride and the reinforcing steel in painted concrete is little corroding.

• Magazine of the Korea Concrete Institute
• /
• v.14 no.3
• /
• pp.71-76
• /
• 2002

콘크리트는 거의 반영구적인 재료라고 인식되어져 왔으나, 최근들어 해양환경, 적설한랭지대, 도심과 같은 열악한 환경속에서 예상보다 빨리 조기열화 되는 현상이 널리 알려지면서 콘크리트 구조물의 구조적 성능뿐만 아니라, 장기적인 내구성에 대한 관심이 높아져 가고 있다. 실제로 여러 선진국에서 염해와 같은 열화환경의 피해를 받은 콘크리트 구조물이 예상공용년수 이전에 철거되거나. 개보수 비용이 초기 건설비용보다 더 많이 드는 예가 적지 않게 보고되면서, 적절한 내구성 유지대책 및 구조물의 장수명화를 위해 많은 연구와 노력이 진행되고 있다.(중략)

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2017.05a
• /
• pp.116-117
• /
• 2017

The most important factor when designing coastal and offshore concrete structures is durability. However, concrete in marine environment is exposed to physical and chemical deterioration of seawater, which might easily lead to low quality. The purpose of the present study is to understand advantages of adding ground solidificaton materials by comparatively analyze the seawater resistance of general concrete and environmental-friendly ground solidification materials.

• Journal of the Korean GEO-environmental Society
• /
• v.16 no.9
• /
• pp.5-12
• /
• 2015

A large amount of dredged soils occur in the marine purification project but dredged fine-grained soils have been abandoned as a waste. The standards as filling materials, banking materials, revetment blocks and concrete blocks were surveyed. Through the geotechnical tests of marine dredged fine-grained soils and the alkali-activation reaction, the usability as banking materials, revetment blocks and concrete blocks were analyzed. Dredged sands could be used as banking materials, and dredged fine-grained soils could be used as filling materials. A mixture of dredged fine-grained soils and dredged sands could be used as banking materials. Materials produced by the alkali-activation reaction could be used as a revetment block and a concrete block.

• Advances in concrete construction
• /
• v.7 no.4
• /
• pp.203-210
• /
• 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.

• International Journal of Highway Engineering
• /
• v.15 no.1
• /
• pp.1-9
• /
• 2013

PURPOSES: The purpose of this study is to evaluate physical properties, durability, fatigue resistance, and long-term performance of poly-urethane concrete (PU) which can be possible application of thin layer on long-span orthotropic steel bridge and to check structural stability of bridge structure. METHODS : Various tests of physical properties, such as flexural strength, tensile strength, bond strength and coefficient of thermal expansion tests were conducted for physical property evaluation using two types of poly urethane concrete which have different curing time. Freezing and thawing test, accelerated weathering test and chloride ion penetration test were performed to evaluate the effect of exposed to marine environment. Beam fatigue test and small scale accelerated pavement test were performed to assess the resistance of PU against fatigue damage and long-term performance. Structural analysis were conducted to figure out structural stability of bridge structure and thin bridge deck pavement system. RESULTS: The property tests results showed that similar results were observed overall however the flexural strength of PUa was higher than those of PUb. It was also found that PU materials showed durability at marine environment. Beam fatigue test results showed that the resistances of the PUa against fatigue damage were two times higher than those of the PUb. It was found form small scale accelerated pavement test to evaluate long-term performance that there is no distress observed after 800,000 load applications. Structural analysis to figure out structural stability of bridge structure and thin bridge deck pavement system indicated that bridge structures were needed to increase thickness of steel deck plate or to improve longitudinal rib shape. CONCLUSIONS: It has been known that the use of PU can be positively considered to thin layer on long-span orthotropic steel bridge in terms of properties considered marine environment, resistance of fatigue damage and long-term performance.