• Fire Science and Engineering
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• v.23 no.4
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• pp.7-12
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• 2009

As the concrete strength increases the degree of damage caused by the spalling becomes more serious because of the permeability. It is reported that the polypropylene (PP) fiber has an important role in protecting concrete from spalling. However, the excessive usage of PP fiber would not useful in spalling control and would decrease the workability of ultra high strength concrete. The high-temperature behaviors of high-strength reinforced concrete columns with various dosage of PP fibers and three types of fire endurance fibers were observed this study. In results, the ratio of unstressed residual strength of columns, in case of concrete strength 60MPa, increases as the dosage of PP fiber increases from 0% to 0.2%, however, the effect of fiber dosage on residual strength of column barely changes above 0.2% and in case of concrete strength 120MPa, PVA fiber is the most suitable fire endurance fiber in accounting fire endurance performance and workability.

• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.821-826
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• 2008

This study evaluated spalling and internal temperature distribution after elevated temperatures test for high strength concrete ($f_{ck}=60\;MPa$) column member with various polypropylene fiber volume fractions. The ISO-834 time-temperature curve was used for measurement of fire resistance properties. As the result of test, average internal temperature results indicated to low temperature in increased polypropylene fiber volume fraction. But, the highest internal temperature results show that does not difference in proportion of polypropylene fiber volume fractions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3C
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• pp.219-228
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• 2006

In this study, a series of fire tests was carried out to evaluate fire-induced damage to structural members in tunnels. From the tests, the loss amount of concrete materials under the RWS scenario was slightly bigger than under the RABT fire scenario. Especially under the RWS fire scenario where the maximum temperature is over $1,200^{\circ}C$, the loss of concrete materials was mainly induced by melting. Generally, the loss of materials in reinforced concrete was slightly smaller than that in unreinforced concrete. Depending upon an applied fire scenario, fire-induced damage to shotcrete was quite different. From the realtime investigation of a specimen surface by a digital camcorder, it was proved that the material loss under the RABT fire scenario was mainly induced by spalling. However, it was also revealed that although fire-induced damage in the initial heating stage under the RWS was so close to that under the RABT, the material loss under the RWS at the later stage after 50 minutes elapsed since fire initiation was induced not by spalling but by melting.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.4
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• pp.115-122
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• 2008

This paper is to investigate the affecting factors on spalling of the high strength concrete including W/B, air content and moisture condition as well as PP fiber contents subjected to fire. An increase with 0.05% of PP fiber resulted in a reduction of slump flow by as much as 11%. Ten percent of air contents due to excessive amounts of AE agent does not lead to variance of slump flow, regardless of PP fiber content. For the effect of the compressive strength, high strength concrete with 15, 25 and 35% of W/B gained 60 MPa~100 MPa of the compressive strength. High strength concrete with H-air had half of compressive strength of that with L-air due to large amount of air. Fire test was conducted in accordance with KS F 2257-1 for 1 hour. Spalling did not occur with all specimens containing more than 0.10% of PP fiber except those with 15% of W/B. Moreover, it is interesting to note that the specimens with more than 10% of air content and with oven dried condition, respectively, had no spalling even if the content of PP fiber is 0.05 vol.%.

• Journal of the Society of Disaster Information
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• v.8 no.1
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• pp.18-26
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• 2012

Accordingly architectural structure is getting high-rise and bigger, a use of high strength and high performance concrete has been increasing. High performance concrete has cons of explosion in a fire. This Explosion in the fire can cause the loss of the sheath on a concrete surface, therefore it effects that increasing a rate of heat transmission between the steel bar and inner concrete. Preventing this explosion of high performance concrete in the fire, many kinds of researches are now in progressing. Typically, researches with using Polypropylene-fiber and Steel-fiber can prove controling the explosion, but the reduction of mobility was posed as a problem of workability. Consequently, to solve the problem as mentioned above, concrete cans secure fire resisting capacity through the using of coating liquid, including Ester-lubricant and non-ionic characteristic surfactant. This research has been drawn a ideal condition in compressive strength areas of concrete by an experiment. When applying 13mm of polyamide-fiber, proper fiber mixing volume by compressive strength areas of concrete is $0.8kg/m^3$ in 60MPa, $1.0kg/m^3$ in 80MPa, $1.5kg/m^3$ in $100MPa/m^3$. These amount of a compound can control the explosion.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.473-474
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• 2009

In this study, a column member of an existing architecture finished with gypsum board was assumed to examine fire resistance characteristics according to the type and thickness of finishing material. All specimens showed spalling to the reinforcing part after fire resistance test. For temperature characteristics, rapid temperature increase of 100${\sim}$200 $^{\circ}C$ was shown between 35 ${\sim}$ 60 minutes in the sequence of 9.5 T, 9.5 T (2 pieces), 12.5 T, 15 T and fire resistant 12.5 T. The analysis suggested that finishing materials with better fire resistance are necessary.

• Fire Science and Engineering
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• v.25 no.5
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• pp.8-13
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• 2011

High strength concrete is the occurrence of explosive spalling associated with high temperature such as a fire. The spalling causes the sever reduction of the cross sectional area with the exposure of the reinforcing steel, which originates a problem in the structural behaviour. The purpose of this study is to investigate the mechanical properties of lightweight mortar using perlite and polypropylene fiber for fire protection covering material. For this purpose, selected test variables were the ratio of water to cement, the ratio of cement to perlite, contents of polypropylene fiber. As a result of this study, it has been found that addition of perlite and polypropylene fiber to mortar modifies its pore structure and reduces its density. And it has been found that a new lightweight mortar can be used in the fire protection covering material.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.154-154
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• 2011

최근 세계 각지에서 발생하는 대규모 터널 화재사고는 많은 사상자를 동반하고 이에 따른 경제적, 사회적 손실 또한 방대하게 진행되는 실정이다. 터널 구조물의 화재 특성상 외부에 쉽게 노출되지 않기 때문에 화재 발생 시 화재에 노출된 표층이 박리되거나 비산해서 단면결손이 생기는 폭렬 현상(explosive spalling)이 발생하게 된다. 이러한 폭렬 현상은 붕괴와 같은 대형 참사로 이어질 가능성이 크다. 따라서 본 연구에서는 터널 내 화재 발생 시 콘크리트 구조물의 폭렬에 의한 붕괴를 예방하기 위하여 이액형 상온경화 실리콘 고무와 인체에 무해한 친환경 첨가제인 펄라이트를 일정한 혼합비(5wt%, 10wt%, 15wt%, 20wt%)로 혼합하여 고성능 난연 복합체를 제조하고, 열적 특성과 난연 특성을 연구를 진행하였다. 열적 특성에 관한 시험으로 TGA를 측정하였으며, 난연 특성에 관한 시험으로는 화염 시험, 내화로 시험, 탄화로 시험을 진행하였다. 우선 TGA 시험은 $20^{\circ}C/min$ 승온 속도로 $800^{\circ}C$까지 실험을 하였고, 화염 시험은 제작한 시편과 gas torch($1200^{\circ}C$)의 화염 거리를 약 10cm로 하여 약 1시간 동안 시험을 하였다. 내화로 시험은 내화로 장치를 이용하여 RABT curve(5분만에 $1200^{\circ}C$도달 후 한 시간 동안 유지 후 냉각, 총 시험 시간 180분) 조건을 만족하는 환경에서 제작한 시편을 콘크리트에 부착하여 콘크리트의 내부온도를 측정하였다. 탄화로 시험은 탄화로 장치를 이용하여 $2^{\circ}C/min$ 승온속도로 $900^{\circ}C$까지 실험을 하여 외부 형태 변화를 관찰하였다. 각각의 시험 결과 TGA 열분해 결과 순수한 실리콘 고무보다 난연제인 펄라이트를 첨가했을 때 더 높은 온도에서 초기 분해 거동을 보였으며, 최종 잔류량은 80%를 보였고, 5 wt%의 펄라이트가 혼합된 시편의 최종 잔류량이 높은 것으로 보아 열분해에 가장 강한 조성임을 알 수 있었다. 화염 시험 결과 펄라이트가 혼합된 모든 시편에서 $300^{\circ}C$가 넘지 않은 결과를 보였다. 이는 제조된 복합체가 화염에 직접적으로 장시간 노출이 되어도 안전하다는 것을 알 수 있다. 내화로 및 탄화로 시험 결과 펄라이트가 15wt%와 20wt%가 첨가된 시편들보다 5wt%와 10wt% 첨가된 시편들이 고온에서 안정하다는 것을 보였다.

• Fire Science and Engineering
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• v.24 no.4
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• pp.41-46
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• 2010

High strength concrete (HSC) has been mainly used in large SOC structures. HSC have superior property as well as improvement in durability compared with normal strength concrete. In spite of durability of HSC, explosive spalling in concrete front surface near the source of fire occurs serious problem in structural safety. Therefore, this study is concerned with experimentally investigation of fire resistance at high temperature due to fireproof material covering thickness in addition to concrete cover. From the test result, it was appeared that the use of fireproof material results in good performance for fire resistance and spalling prevention, and the optimal fireproof covering thickness is 1~3mm. On the other hand, the temperature was rapidly increased by explosive spalling within 30 minutes and showed very little rise caused by evaporation heat after then. It was also found that the void channel was remained at high temperature as PP fiber melts at about $200^{\circ}C$, and the pore pressure in concrete was decreased.

• Magazine of the Korea Concrete Institute
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• v.17 no.3 s.86
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• pp.20-25
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• 2005