• Journal of the Korea Concrete Institute
• /
• v.14 no.5
• /
• pp.708-717
• /
• 2002

Durability is a major concern in the design and construction of concrete structures which are located in the sea environments. In particular, the combined action of chlorides, sulfates, and carbonation nay influence greatly the deterioration behavior of concrete structures. The purpose of the present study is to explore the diffusion characteristics of chloride ions in concrete structures under combined deterioration conditions. The present test results indicate that the chloride penetration into concrete structures is more pronounced under combined attacks of chlorides, sulfates and carbonation. The diffusion coefficients and surface chloride contents were found to increase under combined multiple deterioration conditions. The present study provides quantitatively the penetration and diffusion characteristics of chloride ions in concrete structures under various deterioration conditions. The results of present study may be efficiently used for the realistic design of concrete structures under combined deterioration conditions.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.782-785
• /
• 2004

Salt attack is one of the serious deterioration factor with respect to the durability of concrete structure. Especially, in case of exposed rebar concrete structure in marine environment, corrosion of rebar is accelerated by penetration of $Cl^-$ from exterior. Through this path, volume of corroded rebar is increased about two and half times due to increased inner pressure originated from rust. As a consequence, the overall deterioration of concrete structure, namely, cracks, reduction of adhesive strength and pop-out is followed. In this paper, the effect of structure treatment of concrete on chloride resistance has been investigated. At the same time, the relationship among several characteristics, such as resistance to chloride, water absorption coefficient and surface hardness of concrete has been investigated. It is believed that surface performance improvement by the application of penetrative hardening agent influences on positively water absorption coefficient, surface hardness of concrete and resistance to chloride ion penetration.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.14 no.1
• /
• pp.71-77
• /
• 2010

The concrete structure's durability and integrity is reduced owing to various deterioration phenomena. Therefore, it is important to prevent the deterioration phenomena. This study inquired into the various experimental results of specimens with different dilution concentration and impregnation time by the each solution to present the economic and efficient using method of the inorganic surface penetration agents. As a results, the reasonable dilution concentration and impregnation time of colloidal silica solutions are 15% and 5 minute and for the sodium alumina silicate solutions are 17% and 10 second.

• Journal of the Korea Concrete Institute
• /
• v.17 no.4 s.88
• /
• pp.489-498
• /
• 2005

Recently, the deterioration of concrete structures have been increased by the damage from salt, carbonization, freezing & thawing and the others. Therefore, the measures for the deterioration of concretes have been taken. Among them, it has been often used that surface treatment which cut off the deterioration factors of durability by protecting the surface of concrete. The water proof and repair materials for concrete mainly use organic materials such as epoxy, these materials excel in intial bonding force and resistance to chemical agents. But they cause difference in the modulus of elasticity and the rate of shrinkage and expansion of concrete, and thus result in such problems as scaling and spatting in the progress of time. Therefore in this study it develop the performance Improving agent of concrete surface that can block a deterioration cause such as $CO_2$ gas, chloride ion and water from the outside and enhance waterproofing ability by reinforcing the concrete surface when applying it to concrete structures.

• Journal of the Mineralogical Society of Korea
• /
• v.19 no.4 s.50
• /
• pp.383-392
• /
• 2006

Calcium carbonate stone deterioration has been intensified in urban area, mainly due to the action of atmospheric pollutant. Samples from the black surface layer were examined under petrographic and scanning electron microscope, coupled with energy dispersive X-ray analyser X-ray fluorescence and X-ray diffraction analysis was also carried out for chemical composition and mineral phase analysis, respectively. Moreover, sulphur isotope ratio was measured, in order to identify the origin of sulphate compounds in the black surface layer. Optical and electronic petrographic analysis indicated that gypsum and Quartz were contained in the black surface layer and led to microcracks. Microstructure and chemical composition analysis showed that the interface between black layer and original stone is not black but its characteristic is similar to black layer The results indicated that during deterioration process the black layer can be expanded gradually into the interface by adsorption of atmospheric pollutants. The sulphur isotope analysis demonstrates that there are different origins of the sulphur component in black surface layer.

• Proceedings of the KIEE Conference
• /
• 2001.11a
• /
• pp.227-230
• /
• 2001

This paper divides the factors of an accident into two parts, that are electrical deterioration and thermal deterioration, to analyze a characteristic of the factor of an accident which can break out in the capacitor of metal vaporized polypropylene film. For the purpose of creating capacitor which is caused by electric deterioration, we applied DC overvoltage, induced self-healing and breakdown from element. We applied gradual heat to get an element which is cause by thermal deterioration. The chemical structure of the shape and surface is analyzed by thermogravimetric analyzer (TGA), Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectrometer(FT-IR). As a result, the peak of methylene group came out, in case of electrical deterioration, as observing the self-healing point. However, the peak is disappeared in the heat treated element by 500[$^{\circ}C$], and the peak of carbonyl group which has C=O came out in case of thermal deterioration.

• Structural Engineering and Mechanics
• /
• v.54 no.2
• /
• pp.319-336
• /
• 2015

Life cycle performance of corrosion affected RC structures is an important and challenging issue for effective infrastructure management. The accurate condition assessment of corroded RC structures mainly depends on the effective evaluation of deterioration occurring in the structures. Structural performance deterioration caused by reinforcement corrosion is a complex phenomenon which is generally uncertain and non-decreasing. Therefore, a stochastic modelling such as the gamma process can be an effective tool to consider the temporal uncertainty associated with performance deterioration. This paper presents a time-dependent reliability analysis of corrosion affected RC structures associated bond strength degradation. Initially, an analytical model to evaluate cracking in the concrete cover and the associated loss of bond between the corroded steel and the surrounding cracked concrete is developed. The analytical results of cover surface cracking and bond strength deterioration are examined by experimental data available. Then the verified analytical results are used for the stochastic deterioration modelling, presented here as gamma process. The application of the proposed approach is illustrated with a numerical example. The results from the illustrative example show that the proposed approach is capable of assessing performance of the bond strength of concrete structures affected by reinforcement corrosion during their lifecycle.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.6 no.2
• /
• pp.255-261
• /
• 2002

Concrete structures stand in poor surrounding than it has ever been met before, because they are installed in severe conditions such as chloride penetration. $CO_2$ gas, water and so on. Therefore, the countermeasure to efficiently protect from the deterioration of concrete structures should be urgently considered. From this point of view, this study was aimed to develop surface treatment systems for concrete structures, which cover physical properties, long term durability and economic consideration. Developing the optimal surface treatment materials, powder type polymer or liquid type polymer was added to inorganic base materials. Three surface treatment materials which had shown best results in primary tests were selected and durability tests were fulfilled. Consequently optimum surface treatment material was developed. The surface treatment materials, which were developed through this study, can efficiently extend the service life of concrete structures. As a result, the life cycle cost should be reduced and the waste of material resources would be cut down.

• Journal of Conservation Science
• /
• v.25 no.4
• /
• pp.347-361
• /
• 2009

The Pohang Chilpori is the area with abundant petroglyphs in Korea. The form of the shield, female sex organs, and yut board on the outcrops or float rocks which are composed of the rhyolitic rock are engraved on Chilpori and Shinheungri Petroglyphs. The rhyolitic rock is composed of the phenocryst and groundmass with quartz and feldspar. The rock surface shows mostly yellowish brown color and the rock surface is very irregular by serious weathering, and illite and kaolinite, a kind of the clay minerals, are produced. Deterioration aspects are mainly of surface exfoliation, grain peel-off, damages, scribbling. Chilpori Petroglyph (1) plane has been eroded by running water, in (2) plane has been abrased is on the rock surface, in (3) plane shows surface exfoliation and the various part of the rock surface in plane (4) has become the soil. The corrasion and black phenomenon of the Shinheungri Petroglyph (1) plane was formed by running water, and surface exfoliation and scribbling in plane (2) is serious. Deterioration factors are geomorphologic states, plants, rock of weak to weathering, and artificial influence such as a scribbling and a forest fire. For conservation of the these petroglyphs, study for rock surface conservation and the arrangement of around petroglyphs and construction of water wall are necessary.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.176-179
• /
• 2004

The latest concrete structure has showed that the deterioration of durability has been increased by the damage from salt, carbonization, freezing & thawing and the others. Therefore, the measures for the concrete which has deteriorated durability have been taken. Among them, it has been often used that surface treatment which cuts off the deterioration factors of durability by protecting the surface of concrete. This study was evaluated the surface improving agent for permeability, watertightness, air-permeability, chemical resistance and elution resistance.