• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.04a
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• pp.340-345
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• 2010

국내의 건축물은 강한 내력을 갖기 위해 사용되는 HSC빈도가 점진적 증가하고 있으며, HSC로 시공되어진 건축구조물에서의 화재 발생시 폭렬현상의 문제점이 대두되고 있다. 이에 국내외에서 폭렬현상에 대한 연구들이 진행되었고, 이를 통해 폭렬현상에 원인을 알게 되어 이를 토대로 폭렬 방지 방안을 세웠다. 이에 따라 폭렬현상의 원인 중 합수율이 있으며, 이는 콘크리트가 함유하고 있는 수분으로 고온시에 팽창하여 폭렬현상의 매커니즘이 형성된다. 또한 이러한 함수율이 폭렬 발생에 미치는 영향을 크게 하는 요인으로 탄산화와 양생방법이 있다. 우선 탄산화는 반응을 일으킬 경우, 생성물이 공극을 채워 고온시 팽창된 수분이 외부로 나가는 것을 방해하여 수증기압을 축적시키고, 양생방법에 따라 함수율이 달라지게 되어 고온시 팽창될 수분의 양을 결정하게 된다. 특히, 함수율에 의해 발생되는 폭렬을 방지하기 위해 고강도 콘크리트 내부의 수분을 제거하는 강제건조를 하거나 팽창된 수분이 빠져나갈 곳을 만들기 위해 고온에서 녹는 PP섬유를 사용해 공극을 만들어주는 방법이 있다. 따라서 본 연구는 HSC의 폭렬현상방지 대책을 위한 기초자료를 제시하고자 한다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.381-384
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• 2008

This study investigated spalling prevention and fire resistance properties of the high strength concrete using pre-mixed cement containing fiber to prepare the method for the effective throwing of hybrid fiber. For result of a fire test, almost specimens were protected from fire except 15% of W/C. Totally, the pre-mixed cement containing fiber was favorable compared with passive mixing method for the spalling prevention. It is more effective to prevent spalling caused by fine diversion of fiber even in high strength concrete because it contained many corporate materials. Moreover, the temperature history of the side steel bar on the column test with pre-mixed cement containing fiber did not over 538$^{\circ}C$ which is the average for the standard of fire resistance performance.

• Journal of the Korea Institute of Building Construction
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• v.9 no.6
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• pp.113-119
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• 2009

This study is to investigate the fundamental and fireproof qualities of high strength concrete corresponding to changes in the curing factors and the PP fiber ratio. The results were as follows. For the fundamental characteristics of concrete, the fluidity was reduced in proportion to the increase in the PP fiber ratio. The compressive strength was somewhat reduced according to an increase in the PP fiber ratio. However, it had the high strength scope of more than 60 MPa at 7 days and of more than 90 MPa at 28 days. On the spalling mechanism followed by changes of the water content ratio, spalling was prevented in all combinations, except the specimen without PP fiber and subjected to 3.0% of moisture contents. When spalling was prevented at that time, the residual compressive strength ratio was 22%~41% and the mass reduction ratio was 5%~7%, which was relatively favorable. As the spalling mechanism corresponds to changes in the curing method, spalling was prevented in concrete with a PP fiber mixing ratio of more than 0.05% in the event of standard curing, and in concrete with a PP fiber mixing ratio of more than 0.10% in the case of steam curing and autoclave curing. In these cases, when spalling was prevented, the residual compressive strength ratio was 23~42% and the mass reduction ratio was 7~11%. In these results, the ease of spalling prevention in high strength concrete was inversely proportional to the water content ratio. Depending on the curing method, spalling was prevented in concrete with over 0.05% PP fiber with standard curing and in concrete with over 0.1% PP fiber with steam curing and autoclave curing.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.865-868
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• 2008

As a part of a series of study, this study reviewed the fire proof characteristics of high performance concrete RC column members using non-stripping form that accompanied metal lath lateral confinement to prevent spalling of high performance concrete which is increasingly used recently, and the results are as follows. Flow and air amount both satisfied target range, and compressive strength, over 80MPa at age 28 days, showed high strength range. As for spalling characteristics, in the case of plain in which no fiber is mixed, severe spalling occurred, and in the case of 0.05% nylon("NY" hereinafter)+polypropylene("PP" hereinafter) fiber mixture, only surface area experienced partial spalling. Regarding non-stripping form changes, both non-stripping 25-20 and non-stripping 50-20 experienced spalling at finish material area, and non-stripping 50-20 showed better spalling proof performance than non-stripping 25-20. In the case of non-stripping 50-40, spalling was prevented, and while mass reduction rate was less than 10%, its temperature hysteresis showed the most excellent fire proof performance with base metal surface area maximum temperature $376.1^{\circ}C$.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1105-1108
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• 2008

This paper investigated measures of spalling prevention and mechanism to secure stability of subjected to a fire circumstance. The results were summarized as following. 1) There were 4 kinds of methods for spalling prevention, such as declining percentage of water content and cement water ratio, isolating from high temperature with fire proof covering, giving lateral resistance stress, and discharging vapor pressure using fibers. 2) It was confirmed that methods using fibers to a new construction and fire proof covering to a existing construction on the basis of investigation for the spalling mechanism through the existing theory of spalling and a new theory of WPB.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.475-476
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• 2009

This study investigates fundamental and spalling resistance properties of high strength concrete, W/B 28%, designed with the various diameters and contents of PET fiber. The flowability and compressive strength showed similar tendency in the range of below 0.05vol.% of fiber content. For the spalling resistance properties after fire test, the specimens with 40${\mu}m$ diameters of fiber did not spall at 0.05vol.% of fiber content. And the specimens with 20${\mu}m$ diameters of fiber did not spall even at 0.03vol.% of fiber content.

• 레미콘
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• no.7 s.88
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• pp.10-19
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• 2006

• Journal of the Korea Institute of Building Construction
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• v.14 no.3
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• pp.223-229
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• 2014

In this study, the fire resistance of high strength concrete with organic fibers and polymer powder (PW) was investigated. Two types of the specimens of ${\phi}100{\times}200mm$ and $300{\times}300{\times}600mm$ sizes were prepared. As a result of the test, it was found that the fiber-to-PW mixing ratio of 1:1 achieved the highest fluidity. Further, it was found that the mixing ratios of PP 0.05% + PW 0.05%, PNY 0.05% + PW 0.05% was sufficient to protect the high strength concrete from spalling. For the mock-up specimens of $300{\times}300{\times}600mm$ size, if the required amounts of fibers were added in the concrete. the concrete spalling was resisted. Likewise, in the case of the polymix (PM) together with PW, all the tested specimens were satisfactory for fire resistance performance.

• Fire Science and Engineering
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• v.23 no.6
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• pp.126-134
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• 2009

In an attempt to control the spalling in high strength concrete, spalling reducer was mixed to identify the effect and thermal characteristics of concrete beam member at high temperature. The member was manufactured in such as way of adding 40~60MPa of high strength concrete into spalling reducer, and then fire resistance performance were monitored under the ISO standard fire load condition in accordance with KS F 2257. As a result of test, fore rate performance of 40MPa beam without spalling reducer was 180minutes, 50MPa was 174minutes and 60MPa was 152minutes, indicating that 50MPa and 60MPa beam appeared 6~28minutes short to become a 3-hour rate. However, 50 and 60MPa beam mixed with spalling reducer appeared to have satisfied the requirements for 180minutes. A spalling was occurred in surface of 50 and 60MPa beam mixed without spalling reducer, while no spalling or surface failure was occurred with 50 and 60MPa beam mixed with spalling reducer. Thus polypropylene fiber mixed with the concrete proved to be effective, but viewing that the surface of 60MPa was peeled off partially, the steel fiber mixed appeared not to be effective for the beam more than 60MPa.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.953-956
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• 2008

The present study was to develop a dry PFB method similar to the existing gypsum board construction method in order to apply the existing wet PFB method that uses fire.resistant adhesive. It was found that the existing wet method can produce concrete compressive strength of 80MPa and fire resistance of 3 hours with 30mm PF boards. The goal of development in this study was fire resistance of 3 hours through dry construction of 15mm fire.resistant boards.According to the results of fire resistance test, when the dry PF method was applied, the temperature of the main reinforcing bar was 116$^{\circ}$C in 15mm, 103.8$^{\circ}$C in 20mm, and 94$^{\circ}$C in 25mm, and these results satisfied the current standards for fire resistance control presented by the Ministry of Land, Transport and Maritime Affairs. When a 3.hour fire resistance test was performed and the external properties of the specimen were examined, the outermost gypsum board hardly remained and internal PF board maintained its form without thermal strain.