• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.165-169
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• 2005

The fire damage of building wouid effect on the safety of structure. When the reinforced concrete structure is heated by high temperature due to the fire, the structural resisting-force will be decreased. In a way, it is a requirement to use high strength concrete for high rise building. Particularly, fire resistance properties of high-strength concrete is more important than normal strength concretes. The fire outbreak of a high strength concrete by sudden temperature rise is a main problem, and causes crack by thermal stress, loading to the deterioration of the durability. In this study, normal and high strength mortar were exposed to a high temperature environment. And than fundamental data for the character change of concrete heated highly were presented by measuring compressive strength of concrete with polypropylene and vinylon fiber, before and after heating. As the results, it is proven that high strength mortar with polypropylene and vinylon fiber for prevents deterioration of durability by fiber.

• Journal of the Korean Society of Safety
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• v.3 no.1
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• pp.31-36
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• 1988

We live in the building which made of concreat. If a fire break out in the building on a sudden, the heated concreat structual of the building were become very weak and bad poor. In this study, it was investigated by test for thermal expansibility and compressive strength of the highly heated concreat. The experiment was carried out in the temparature range of 150―75$0^{\circ}C$. The obtained results are as follow. 1. The heated concreat has weaken in compressive strength from about at 30$0^{\circ}C$. 2. The concreat heated over 45$0^{\circ}C$ is not proper for structual material. 3. The concreat expanded remarkable when it was heated about at 450―$600^{\circ}C$.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.232-236
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• 1993

The Tunnel Form(T/F) system instead of traditional euro form has been tried to reduce construction duration and to improve concrete quality in reinforced concrete wall type apartment construction. To find the relationship for concrete compressive strength between cylinder mold and slab, the different curing locations of concrete cylinder mold in the room have been investigated. The test results showed that the compressive strength of the cylinder concrete with middle-upper location in the room was most near concrete compression strength with respect to slab concrete strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.11a
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• pp.77-82
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• 2003

The purpose of this study is development of technique to use cementitious powder as recycle cement produced from deteriorated Concrete waste which has a large quantity of calcium carbonate. Therefore, after having theoretical consideration based on the properties of high-heated concrete and concerning about neutralization of Concrete, we analysis chemical properties of ingredients of cementitious powder. After making origin cement paste, then processing the accelarated carbonation, we consider the properties of hydration and chemical properties of cementitious powder under various temperature conditions. As a result of the thermal analysis, the CaCo3 content of cementitious powder would affect decision of heat temperature to recover its hydrated ability because CaCo3 content is increased when neutralization is progressed. And as a result of XRD analysis, in case of origin powder of non-neutralized paste, CaO peak is found at 700℃. but, heat temperature to generate CaO would increase when the content of neutralized ingredients is increased. Finally, recycle cement heated at 700℃ shows the best compressive strength when the content of neutralized ingredients in recycle cement is less then 50%. However, it would be quite difficult to manage quality of recycle cement according to recycling points of various concrete waste.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.77-82
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• 2003

The purpose of this study is development of technique to use cementitious powder as recycle cement produced from deteriorated Concrete waste which has a large quantity of calcium carbonate. Therefore, after having theoretical consideration based on the properties of hish-heated concrete and concerning about neutralization of Concrete, we analysis chemical properties of ingredients of cementitious powder After making origin cement paste, then processing the accelerated carbonation, we consider the properties of hydration and chemical properties of cementitious powder under various temperature conditions As a result of the thermal analysis, the CacO3 content of cementitious powder would affect decision of heat temperature to recover its hydrated ability because CacO3 content is increased when neutraliTation is preBlessed. And as a result of XRD analysis. in case of origin powder of non-neutralized paste, CaO peak is found at $700^{\circ}C$. but, heat temperature to generate CaO would increase when the content of neutralized ingredients is increased. Finally, recycle cement heated at $700^{\circ}C$ shows the best compressive strength when the content of neutralized ingredients in recycle cement is less then 50%. However, it would be quite difficult to manage quality of recycle cement according to recycling points of various concrete waste.

• Fire Science and Engineering
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• v.3 no.2
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• pp.3-10
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• 1989

The results on high strength concrete by heating high are as follows: 1. High strength concrete appeared an estimated 5.5% higher than ordinary concrete in the central temperature of specimens by heating. 2. High strength concrete is higher than ordinary concrete in the decreased width of the ratio on the residual compressive strength by heating high. According to heating temperature and time, the inferred formula of compressive strength on high strength concrete showed: Fc=-0.53Te -2.4Ti +748.4

• Journal of the Korean Society of Safety
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• v.12 no.2
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• pp.140-145
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• 1997

The main purpose of this study is to establish the reliable method for evaluating fire damage of reinforced concrete building, by using the rational procedure, and to develope the rehabilitation methods of fire damaged concrete structures. Especially, this proposed evaluation method is applied to the fire damaged concrete buildings of domestic, and the rehabilitation methods on the basis of these applied results are proposed and those example are shown. The proposed rational evaluation method for fire damaged concrete building proceeds is estimating the reduction of the mechanical properties of concrete of fire damaged structural members in comparison with the experimental results which are obtained from the compression tests of heated concrete specimens under various temperatures.

• Journal of the Korea Institute of Building Construction
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• v.8 no.5
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• pp.53-58
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• 2008

This study is to investigate experimentally residual strength properties of the high strength concrete containing the hybrid of nylon and polypropylene fiber at elevated temperature. Test results showed that specimens heated up to $300^{\circ}C$ exhibited similar strength properties to the one at room temperature. This result is significantly different from previous studies. but specimens heated over $400^{\circ}C$ showed dramatic decrease indicating similar tendency. For the residual strength properties, one at $300^{\circ}C$ even increased 10%, which is also different from previous studies, but it significantly decreased in $400^{\circ}C$ as widely expected. Melted pores by organic fibers in concrete specimens was observed with FE-SEM. For the density of concrete in elevated temperature, internal system in $200^{\circ}C$ had even denser than in $20^{\circ}C$, but was collapsed in $400^{\circ}C$.

• Journal of the Korea Institute of Building Construction
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• v.4 no.3
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• pp.143-151
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• 2004

The purpose of this study is development of technique to use cementitious powder as recycle cement produced from deteriorated Concrete waste which has a large quantity of calcium carbonate. Therefore, after having theoretical consideration based on the properties of high-heated concrete and concerning about neutralization of Concrete, we analysis chemical properties of ingredients of cementitious powder. After making origin cement paste, then processing the accelarated carbonation, we consider the properties of hydration and chemical properties of cementitious powder under various temperature conditions. As a result of the thermal analysis, the $CaCO_3$ content of cementitious powder would affect decision of heat temperature to recover its hydrated ability because $CaCO_3$ content is increased when neutralization is progressed. And as a result of XRD analysis, in case of origin powder of non-neutralized paste, CaO peak is found at $700^{\circ}C$. but, heat temperature to generate CaO would increase when the content of neutralized ingredients is increased. Finally, recycle cement heated at $700^{\circ}C$ 120min. shows the best compressive strength when the content of neutralized ingredients in recycle cement is less then 50%.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.509-512
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• 2003

Dehydration and micro crack thermal expansion occur in cement hydrates of concrete structure heated by fire for a long time. The characteristic of concrete exposed to high temperature can be analyzed from distribution of porosity and pore size. Porosity showed a tendency to increase irrespective of specimen types. This is due to both the outbreak of collapse of gel comprising the cement and a micro crack by heating. Porosity did not affect the variety of specimen and increased with the same tendency throughout every specimen. In addition, the deteriorate of compressive strength resulted from increase in porosity