• Corrosion Science and Technology
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• v.4 no.5
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• pp.207-210
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• 2005

Coating performance of various coating systems including chlorinated rubber and epoxy/urethane used most for steel structures of highway in Korea, was evaluated by exposing test specimen to complex deterioration factors such as ultraviolet ray, moisture, freeze-thaw cycle and salt. Deteriorated specimens were evaluated by chalking and rust grades according to ASTM, and measurement of color differences and adhesion. In overall coating performances such as corrosion resistance, photochemical stability, and adhesion, ceramic/ urethane, moisture-curable urethane/ urethane, etc. were superior. As for other coating materials tested in this study, superior materials against certain deterioration factors may be inferior against other factors. Accordingly, in order to select suitable maintenance coating materials for the use, it is thought that investigation of suitability through experiment should precede selection of materials, especially for unusual coatings or paints.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.589-592
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• 2006

The durability of concrete involves resistance to freeze-thaw action, corrosion, permeation, carbonation, chemical attack and so on. Generally, properties of concrete have been well understood under the separate action of these deterioration mechanisms. However, in practice, the degradation of concrete usually is the result of combined action of physical and chemical attack and can be accelerated by the combined action of several deterioration mechanisms. In the present study, to evaluate the combined deterioration by freeze-thaw action and seawater attack, ground granulated blast-furnace slag or silica fume concrete with water or seawater as mixing water was exposed to 300 cycles of freeze-thaw action. Tests were conducted to determined the relative dynamic modulus of elasticity and compressive strength. Furthermore, The MIP analysis were performed on the deteriorated part of concrete due to freeze-thaw action and seawater attack.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.357-358
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• 2010

This study was performed an evaluation of chloride attack resistance properties of marine concrete by accelerated deterioration test of artificial seawater. As the results of study, when considering the compressive strength and chloride ion penetration of concrete, the proper type to improvement of chloride attack resistance is thought to marine cement.

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.141-151
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• 2000

Compressive strength, sulfate deterioration factor(SDF) and length change of 5 types of mortars immersed in sodium sulfate solution were observed. As the results of tests, it was found that the sulfate resistance of blended cement mortars were superior to that of portland cement mortars. Pore volume with diameter larger than 0.1 $\mu\textrm{m}$ of 5 types of pastes indicated that the micro-structures of blended cement pastes were denser, due to pozzolan reaction and latent hydraulic properties, than those of portland cement pastes. The XRD, ESEM, EDS and TG analyses demonstrated that the reactants such as ettringite and gypsum were significantly formed in portland cement pastes. Besides, compared with the $Ca(OH)_2$ content of ordinary portland cement pastes immersed in water and sodium sulfate solution, the $Ca(OH)_2$ contents of fly ash blended cement and ground granulated blast-furnace slag cement paste were about 58% and 28% in water, and 55% and 20% in sodium sulfate solution, respectively.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.96-103
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• 2012

The purpose of this study is evaluate the ability of coating materials developed in order to prevent the durability deterioration of the concrete structure. Neutralization test, freezing and thawing test, and sulfate resistance test were performed in this study. Test results show that the developed coating material is effective against durability deterioration.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.4
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• pp.223-231
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• 2024

For the OPR1000, a standard power plant in Korea, an analytical model of the containment building considering voids and deterioration was built with multilayer shell elements. Voids were placed in the vulnerable parts of the analysis model, and the deterioration effects of concrete and rebar were reflected in the material model. To check the impact of voids and deterioration on the seismic performance of the containment building, iterative push-over analysis was performed on four cases of the analytical model with and without voids and deterioration. It was found that the effect of voids with a volume ratio of 0.6% on the seismic performance of the containment building was insignificant. The effect of strength reduction and cross-sectional area loss of reinforcement due to deterioration and the impact of strength increase of concrete due to long-term hardening offset each other, resulting in a slight increase in the lateral resistance of the containment building. To determine the limit state that adequately represents the seismic performance of the containment building considering voids and deterioration, the Ogaki shear strength equation, ASCE 43-05 low shear wall allowable lateral displacement ratio, and JEAC 4601 shear strain limit were compared and examined with the analytically derived failure point (ultimate point) in this study.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2126-2127
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• 2011

This paper describes the analysis of deterioration characteristics for connection factor according to connection method of grounding system. The connection method of grounding system is specified in IEC standard. In order to analyze the deterioration characteristics for connection factor, deterioration test was carried out when the connection factor was buried in salt water and underground. The test connection factors were C-type sleeve, clamp, and exothermic welding. As a consequence, most of the connection factor was corroded, and the electrical resistance decreased after deterioration. The analytical results can be used to establish the safety of grounding system.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.54-57
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• 2003

Scaling deterioration of port concrete structures due to the combined effects of chemical actions by seawater and the freeze-thaw action is also a problem which has not yet been fundamentally solved. Furthermore, deterioration of concrete surface was considered as accelerate factor of concrete durability tended to decrease. Therefore, we considered the scaling measuring method and decreasing influence of durability of concrete according to kind of binders, such as OPC, Slag, Slag+Fa, due to freeze and haw of sea water. As a results of this study, it was effective method of scaling deterioration of concrete, and confirmed the salt deterioration resistance effect to use slag binder against to sea water.

• Journal of Korean Association for Spatial Structures
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• v.11 no.1
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• pp.97-104
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• 2011

This paper contains of descriptions of deterioration diagnosis of the surface and a coating layer for maintenance managements of large spatial structures with membrane structure. Membrane is a roofing material of the structures that its performance of durability including its performance of chemical resistance and corrosive resistance is considered to be highly important. In general, the items of diagnosis for maintenance managements such as membrane extensively include the diagnosis of deterioration of the membrane surface, of a coating layer of membrane, the diagnosis of deterioration between a coating layer and fiber, of overall surface of membrane, of the class of ropes, of reinforced belts, and of the cover of rubber. The object of this study that needs maintenance managements of the membrane with PVC and FIFE which are commonly used and shows the diagnosis results of deterioration of the surface and a coating layer.

• Advances in concrete construction
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• v.17 no.1
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• pp.45-52
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• 2024

In this study, the fresh properties of paraffin-mixed concrete, compressive strength, resistance to frost damage, and resistance to composite deterioration under freeze-thaw and salt environment were investigated. The compressive strength of paraffin-mixed concrete was almost the same as that of unmixed concrete, and no decrease in strength was observed, unlike the concrete with entrained air in consideration of freeze-thaw resistance. Concerning the freeze-thaw resistance of paraffin-mixed concrete, the relative dynamic modulus of elasticity (RDME) did not decrease even without entrained air. In addition, no decrease in the RDME was observed in the combined deterioration with salt damage, and it was confirmed that the mass reduction was suppressed compared to the concrete without paraffin. The freeze-thaw resistance of concrete when paraffin is mixed may be improved due to the reduction in the amount of frozen water and the mixed paraffin particles exist in the concrete as pore fillers with a size of 200 ㎛ or less, which act as substitutes for air voids. This resulted in reduction of the apparent air void spacing and thereby relieving the pore pressure.