• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.76-79
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• 1999

The purpose of this study is to investigate the spalling properties of high-performance concrete with the kinds of aggregates and polypropylene(below PP) fiber contents. According to the experimental results, concrete contained no PP fiber take place in the form of the surface spalling and the failure of specimens after fire test regardless of the kinds of aggregates. Concrete contained more than 0.05% of PP fiber with the kinds of aggregates does not take place the spalling. Concrete using basalt has better performance in spalling resistance that concrete using granite and limestone. It is found that residual compressive strength has 50~60% of their original strength. Although specimens after exposed at high temperature are cured at water for 28days, they do not recover their original strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.209-210
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• 2011

This study is aimed to draw a optimum combined fiber mix condition to improve spalling resistance and flowability of ultra high-strength concrete. As a result, W/B 12.5% concrete specimens were prevented spalling with PE0.05+ PP0.1, PE0.05+NY0.1 and W/B 12.5% concrete specimens were prevented spalling with all of combined organic fiber mix condition. But There is no significant influence of steel fiber under 5% volume ratios to prevent spalling. In the scope of this study, we suggest that condition of optimum volume ratio PE0.05+NY0.1 is to improve spalling resistance, flowability and residual compressive strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.155-156
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• 2018

In this study, surface spalling and explosive spalling of ring-type ultra-high strength concrete under rapid heating and slow heating were investigated. In rapid heating, the internal temperature difference of the concrete is large, so that continuous surface spalling occurs. However, in slow heating, the difference in the internal temperature of the concrete is small, resulting in explosive spalling at a time. Since the heating condition has a great influence on the internal temperature of the concrete, it is necessary to consider the spalling of the concrete under various heating conditions.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.83-86
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• 2007

This study provides the practical application of the concrete using fiber to protect from fire studied by previous research. The fluidity and air content is satisfied with the targets, and the compressive strength is over 60MPa on W/B 35% and 80MPa on W/B 20 and 25%. For the properties of the spalling after the fire test, there is no spalling or slight occurrence on the specimens. However, for the RC column, the covering concrete fall off caused by spalling occurrence. Based on the results, it is thought that the fiber content should be put into the safety factor to prevent spalling for the structures.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.421-424
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• 2006

This study, in order for perceiving the mechanical attribute followed by the explosive spalling of high strength concrete material under high temperature and evaluating capacity of endurance of material, targets understanding capacity of endurance of material such as explosive spalling in high temperature, temperature by thickness of clothing, transformation extent, transformation speed and displacement, stocking the maximum load based on the Allowable Stress Design Method. As a result of experimenting the explosive spalling attribute of high strength concrete material, the one possibly causing serious damage is the 50 MPa concrete. In all aspects of 60 MPa concrete, explosive spalling happens. Especially, it is hazardous enough to reveal all the iron bar. All explosive spalling is intensively concentrated on the surface of concrete for the first $5{\sim}25$ minutes, which urges for the explosive spalling protection action. As a result of evaluating the structural safety by the transformation of high strength concrete, while beam assures the fire safety meeting regulation, 60 MPa shows the dramatic increase of transformation, which only counts 84% of safety. In a column, both the concrete exclusion and excessive explosive spalling are concentrated upper part of column, which brings about the dramatic transformation, so it only meets the 50% of safety regulation. Likewise, in 80, 100 MPa concrete which was never experimented considering the condition of domestic structural endurance stocking devices, the faster collapse is expected.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.610-613
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• 2006

This paper is the fundamental study for manufacture of spalling resistance concrete and also analyses the mechanism and spalling resistance method with materials, mixture proportion and lateral confinement. The present work with the basic experiment achieved successful method for spalling resistance using both proper amounts of fiber contents and lateral confinement using metal lath. Moreover, the developed spalling resistance method was applied for full sized column construction in the Doosan We've Poseidon I field, located in Busan city. Authors investigated the physical properties examining workability, placeability and pumpability. These studies are continuously processing to develop new technology expecting remarkable impact on the spalling resistance and fire resistance performance of high-raise building construction in the future.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.11a
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• pp.195-201
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• 2008

When reinforced concrete is subjected to high temperature as in fire, there is deterioration in its properties of particular importance are loss in compressive strength, cracking and spalling of concrete, destruction of the bond between the cement paste and the aggregates and the gradual deterioration of the hardend cement paste. Assessment of fire-damaged concrete usually starts with visual observation of color change, cracking and spalling of the surface. In this paper, it was reported the trends of research and practical use on the Explosive Spalling Properties of the High-Strength Concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.557-560
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• 2004

This paper is to investigate the fire endurance of high performance concrete with the contents of cellulose fiber. According to test results, the use of CL lead to decrease in fluidity. For compressive strength, the use of CL had no influence on compressive strength. For spalling properties, plain concrete showed a severe spalling failure. The use of CL protected from spalling of concrete, but most specimens had scale failure and partial destruction of specimens. This is due to the insufficient fiber length and diameter of CL fiber, which was unable to discharging the internal vapour pressure. For this reason, CL fiber can not be used to protect from spalling oh high performance concrete. Residual strength was observed to $5\~7\%$ of original strength.

• Journal of the Korea Concrete Institute
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• v.24 no.2
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• pp.173-183
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• 2012

Recently, experimental studies to prevent explosive spalling based on spalling mechanism and addition of Polypropylene fiber in high strength concrete (HSC) are performed actively. However, with respect to ultra high strength concrete (UHSC), its compact internal structure is more difficult release vapor pressure at rapid rising temperature compared to HSC. Therefore, in this study, an experiment was conducted to evaluate spalling properties of UHSC using ${\Box}$ $100mm{\times}100{\times}H200mm$ rectangular specimen according to ISO-834 standard fire curve. With respect melting point of fiber, three fiber types of Polyethylene, Polypropylene, and Nylon fibers with melting temperature of $110^{\circ}C$, $165^{\circ}C$, and $225^{\circ}C$, respectively, were considered. Mixed fiber of 0.15% and 0.25% of concrete volume was used to consider spalling properties based on water vapor pressure release. Then, TGDTA test on fiber and FEM analysis were performed. The results showed that it is difficult to prevent initial spalling without loss of fiber mass even if fiber melting temperature is low. Also, in preventing thermal spalling, fiber that melts to rapidly create porosity within 10 minutes of fire is more effective than that of low melting temperature property of fiber.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.51-54
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• 2009

In this study, the fire resistance test was carried out with a parameter such as fiber(PP+NY) mixed ratio on high strength concrete with 80MPa, and the spalling resistance property was evaluated. Concrete material test was carried out with a parameter such as fiber(PP+NY) mixed ratio(0%, 0.05%, 0.1%, 0.2%) of high strength concrete with 80MPa. Although the flowability and the strength capacity were delicately decreased with a increase of fiber mixed ratio, they satisfied the target limits. As the spalling resistance property after the fire resistance test of 3 hours, the spalling was partly shown on the high strength concrete with fiber(PP+NY) mixed ratio of 0% but, wasn't shown on the high strength concrete with fiber(PP+NY) mixed ratio of 0.05% ~ 0.2%.