• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.773-776
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• 2008

The corrosion of steel in concrete is significant in marine environment. Marine bridges are readily deteriorated due to the exposure to marine environment. Salt damage is one of the most detrimental causes to concrete bridges and port structures. Especially, the splash and tidal zones around water line are comparatively important in terms of safety and life-time point of view. During the last several decades, cathodic protection (cp) has been commonly accepted as an effective technique for corrosion control in concrete structures. Zn-mesh sacrificial anode has been recently developed and started to apply to the bridge column cp in marine condition. The detailed parameters regarding Zn-mesh cp technique, however, have not well understood. This study is to investigate how much Zn-mesh cp influences along the concrete column at elevated temperature. About 100cm column specimens with eight of 10cm segment rebars have been used to measure the variation of cp potential with the distance from Zn-mesh anode at both 10$^{\circ}$C and 40$^{\circ}$C in natural seawater. The cp potential change and current diminishment along the column specimens have been discussed for the optimum design of cp by Zn-mesh sacrificial anode

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.5
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• pp.30-36
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• 2019

In order to evaluate service life of RC (Reinforced Concrete) structures exposed to chloride attack, chloride penetration analysis is required referred to the chloride diffusion coefficient from the actual mix proportions. In this work, accelerated diffusion coefficients are obtained from NT BUILD 492 and ASTM C 1202 and the related apparent diffusion coefficients are derived via the previously proposed relationship for RC structures near to sea shore. Considering the properties of the mix proportions and the most conservative analysis conditions like critical and surface chloride contents, service lifes in column and exterior wall member are evaluated through conventional program LIFE 365 ver.2. The different built-up period of 10 and 15 years has no significant effect on service life. The results from mix proportions with slag show longer than 75 years of service life with the help of higher time dependent parameter and lower initial diffusion coefficient.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.6
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• pp.437-443
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• 2009

Impact echo method estimating the soundness of concrete measures the dynamic elastic modulus of specimens which are different with static elastic modulus tested by uni-axial compression test. Thus, this paper investigates the relationships between dynamic and static elastic modulus based on in-situ concrete cores. Also, dynamic elastic modulus was compared with compressive strength. Concrete cores were obtained from about 20 to 70 years concrete structures at three different harbors which were Incheon, Wando, and Masan in Korea. In order to investigate the influence of exposure condition on the relationship, air zone, splash zone, and tidal zone were selected. Different harbors showed the different relationships between dynamic and static elastic modulus, but exposure conditions have no influence on the relationship between dynamic and static elastic modulus. Also, the relationship between dynamic elastic modulus and compressive strength has the same tendency as the relationship between dynamic and static elastic modulus. The relationship equations were proposed to estimate the relationships properly.

• Journal of the Korea Concrete Institute
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• v.29 no.3
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• pp.299-306
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• 2017

In this research, it was examined chloride ion penetration resistance of slag-replaced concrete and cementless slag concrete considering marine environmental exposure conditions of splash zone, tidal zone and immersion zone. In the design strength of grade 24 MPa, the specimens were tested to determine their compressive strength, scanning electron microscopy images and chloride migration coefficient. Further, chloride ion penetration depth and carbonation depth of specimens exposed to marine environment were measured. Experimental results confirm that chloride migration coefficient of specimens tended to decrease with increasing the replacement ratio of ground granulated blast-furnace slag in accelerated laboratory test. In addition, the specimens exposed to the tidal zone were found to be the greatest chloride ion penetration depth compared to splash zone and immersion zone. On the other hand, the chloride ion penetration depth of the specimens exposed to splash zone tended to increase with increasing the replacement ratio of ground granulated blast-furnace slag in contrast with the results for the tidal zone and immersion zone.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.6
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• pp.510-515
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• 2016

Recently, corrosion occurred on the piles of a marine bridge located on the NamHae expressway in Korea. A sacrificial anode cathodic protection system was installed to prevent corrosion damage in the marine bridge. In the case of the marine bridge in this study, the sacrificial anode cathodic protection system was applied at the tidal and splash zones of the piles because the upper part of the structure was not corroded, and because corrosion occurs at the tidal and splash zones due to sea tides. To verify the performance of the sacrificial anode cathodic protection system 8 years later, cathodic protection (CP) current, CP potential, and degree of depolarization were measured. The experimental results on the performance of the sacrificial anode cathodic protection system from a total of 60 piles were classified into 4 categories: good CP effect results (13 piles), partial CP effect results (27 piles), temporarily erroneous results (5 piles), and need for maintenance because of delamination (15 piles). It was determined that additional repairs are required, such as the application of bulk anodes and jacket casings, for piles where the CP effect is poor.