• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.136-143
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• 2010

There are three parts of tunnel which are influenced by outside temperature, entrance, exit and vent. These parts showed different tendency of deterioration(very rapid deterioration speed, wide range of defects, etc) compared with last parts of tunnel. Therefore, it needs to have different points of view when civil engineers analyze the defects on these parts and apply the retrofit or rehabilitation methods for them. However, when we conduct maintenance works, precise inspection and precise safety diagnosis, these defects had been neglected because those were considered as unimportant defects and caused from temporary weather and temperature change. In this study, two urban tunnels were analyzed to decide the range of tunnel which are influenced by outside temperature using a thermal camera, and to find out the causes of defects on these parts. From the results, the main points of maintenance were presented.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.3
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• pp.71-83
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• 2008

In this paper, the basic principle, the application and the limitation of Infrared thermography technique to detect defects in different kinds of concrete structures are reviewed. Considered are voids beneath the concrete surface with experiments, delamination between concrete surface and fiber reinforced polymer sheet, the deterioration of steel bars in reinforced concrete, surface defects in historical buildings, pavements, bridges, and railway track graves. As a result, we conclude that infrared thermography methods are useful for fast detecting defects; however, they are influenced by environmental factors, specially temperature. Therefore it is recommended to use the infrared thermography technique with other NDT equipments to expect better result.

• Cement Symposium
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• no.29
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• pp.201-208
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• 2002

• Journal of the Korea Construction Safety Engineering Association
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• s.29
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• pp.35-44
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• 1998

• Proceedings of the Korean Nuclear Society Conference
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• 2004.05a
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• pp.179.1-179.1
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• 2004

• Cement
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• s.203
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• pp.42-46
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• 2014

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.3
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• pp.167-177
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• 2014

New technologies for water purification are continuously emerging to address global water quality problems, and one such technology involves advanced hermetic water purification facilities made by concrete that utilize ozone treatment processes. Better knowledge about surface deterioration of epoxy coating exposed to ozone treatment is needed as a foundation for development of improved methods and materials in the future. This study utilized atomic force microscopy (AFM), nanoindentation methods, and existing indirect methods such as visual observation, changes in mass, surface observation and chrominance analysis, to evaluate epoxy water-resistance and anti-corrosiveness. This study considered six different epoxy formulations to assess typical degradation characteristics of epoxy surfaces with regard to water-resistance/anti-corrosiveness. AFM and nanoindentation techniques emerged as promising direct methods with potential to provide quantitative measures of surface quality that are improvements upon existing indirect methods. The experiments also confirmed that some of the epoxy-coatings were severely iMPacted by ozone exposure, and thus the results demonstrate that concern about such deterioration is justified.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1065-1068
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• 2008

Marine bridges are readily deteriorated due to the exposure to marine environment. The concrete deterioration occurred by corrosion of steel in concrete is mainly relevant to chloride in seawater. Chloride ions penetrate through porous concrete, and then reach to the reinforcing steel, and finally corroded them. The corrosion by-products(rusts) increase the volume as much as 6 to 10 times of origin steel. this creates expanding pressure and tensile stress, which cause the structures cracking and spalling. Sometimes the rebar corrosion is accelerated, and then collapsed catastrophically. In order to prevent corrosion damage, it is important to understand well regarding the reason of concrete corrosion, the quantification of its damage, and protection method/system to stop or to mitigate the corrosion. In this study, slab specimens were fabricated to evaluate the effect of cathodic protection which was simulated to marine bridges, and/or port structures. Zn-mesh sacrificial anode has been applied as a chathodic protection system and accelerated test conditions, i.e. temperature and salt concentration have been used in this study.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.4
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• pp.387-394
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• 2009

The objective of this study is to evaluate the durability and deterioration of concrete lining in the seven conventional tunnels. These tunnels were constructed about 40~70 years ago, and closed about 10~40 years ago. The field investigation and various laboratory testings were performed for this study. It was observed from the visual, examinations that the concrete linings of 7 tunnels were severely deteriorated, such as, cracks, leakages, desquamation, and exploitations. The compressive strengths obtained from rebound hardness method and uniaxial compressive strength test on core specimens largely differed depending on the locations in the tunnel. The maximum compressive strength of concrete lining was greater about 2 times than the minimum compressive strength of concrete lining in the same tunnel. The results of micro-structural analysis showed that the substances deteriorating the concrete lining, such as ettringite and thaumasite, were detected in the concrete lining of tunnel.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.102-113
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• 2021

The deterioration environments caused by de-icing salt and airborne chlorides in the seashore, evaluated in the "Detailed guideline for safety and management practice of facilities (performance evaluation)", were reviewed in terms of penetrated chlorides into concrete on various road facilities. Target concrete structures, in this study, were 4 concrete barriers in Gangwon area, 3 concrete barriers and 1 retaining wall in Busan area, and 4 bridges in Gangwon-do, Seoul, Gyeonggi-do, and Busan. The deterioration environments were classified into three categories: direct and indirect de-icing salt attack, and airborne salt attack depending on the distance to seashore and the height of pier, and the penetrated chlorides in to concrete were analyzed. The results showed that (1) the regional deterioration environments were clearly classified by de-icing salt sprayed days (snowfall days), (2) the penetrated chlorides increased significantly when leakage occurred through slabs or expansion joints, and (3) the airborne chlorides affected to a height of 20 m concrete in the seashore, Busan. From these, it could be confirmed that the chloride ion penetration properties depend on the exposed aging environment, member location and height, and deterioration status, even on the same structure, so the selection of target members and location is very important in the inspection and maintenance. If the database of penetrated chlorides properties in various deterioration environments is constructed, it is expected that the proactive durability management on concrete structures will be possible in the field.