• Elastomers and Composites
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• v.44 no.3
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• pp.299-307
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• 2009

The effects of reinforcing materials on durability and mechanical properties of V-rib belt were investigated. Cotton fiber and ZnO were used as a filler for CR, and cotton and aramid fiber were used for EPDM rubber compounds. These materials were prepared as a specimen and V-rib belt for heat resistant and mechanical test. High contents of ZnO give improved wear resistance, and higher contents of cotton fiber showed higher durability in high rotation speed but lower wear resistance for CR rubber compounds. Using the aramid and cotton fiber together in EPDM rubber compounds, thermal and wear resistance were improved simultaneously. The material containing EPDM matrix showed better durability and wear resistance than those of containing CR matrix comparing in the same cotton fiber contents.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.653-659
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• 2018

High-rise buildings and complex facilities are a representative urban system for the masses, and it requires an increasing role of commodity and safety. Smoke and toxic gasses can cause accidents due to fire in these systems. The purpose of this study is to develop a fiber screen material for emergency evacuation passages that can be avoided quickly and safely in cases of disasters. The fiber screen material is applicable to folding devices for emergency evacuation passages. The material is different from general steel material in that it is lightweight with less burden during storage for a long time in a roll form in a folding device. It also has an excellent secondary function in that it is less affected by radiant heat. Three kinds of fiber screen materials were selected that have good flame retardancy and post-processing characteristics. A performance evaluation was performed by a heat shrinkage test, contact heat test, combustibility test, flame retardancy test, tensile strength test, and tear strength test. As a result, the lightweight fabric shows excellent performance through post-processing, and silicone resin coating can secure safety of the pizza by the fiber screen material performance and radiant heat. The optimum post-treatment conditions were evaluated by performing a burning test after coating two kinds of glass fibers and four types of flame-retardant silicone resins with different weight and thickness.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.605-608
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• 2008

This study investigated fundamental properties corresponding to mixtures for the high strength, and their properties of spalling prevention after a fire test. The results were summarized as following. For the flowability of using mixtures for the high strength, the target flow was satisfied with a small quantity of high performance reducing water agent to compare with silica fume. For the compressive strength in the case of using mixtures for the high strength, it was higher to compare with silica fume at 7 days, so it was proved that using mixtures for the high strength was profitable to prevent early frost damage. The compressive strength at the 28 days of silica fume and mixtures for the high strength were similar. There was no reduced tendency at the compressive strength according fiber contents, so it found out that the bonding strength between the fiber and concrete was hardly effective. For the spalling properties, the specimens without fibers were destroyed, however using over 0.05% of NY and PP fibers was effective to prevent spalling on the high strength concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.11a
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• pp.7-10
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• 2005

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

• 보존과학연구
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• s.19
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• pp.179-191
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• 1998

The Dumu of casted iron objects which is the big vessel for the prevention of fire to wood building is conserved in Kyongpok Palace(Dumu sizes：diameter 97cm, height 42cm, thickness 2cm, weight 250kg). The treated objects which some parts were lost, were not corroded, but cracted and broken by an external power, and strongly attached an cement layer on inside surface. First of all cement layer was mechanically removed by pneumatic needle scaler, welded to electric method for broken and cracked pieces, and then the lost sections were restored to use a epoxy resin and glass fiber. In order to prevent a damage during the handling, the restoration section of the inside surface was treated different colour in comparison with original part.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.9-15
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• 2010

Recently, the high-compressive strength concrete where the use is extending was weak in fire because of spalling that was occurring with rise of internal vapor pressure by high temperature. For preventing spalling of high-strength concrete in fire, Organic fibers have been using in concrete generally. By melting of organic fibers in concrete in fire, the internal moistures of concrete moves quickly to the outside, and so, preventing of spalling of high-strength concrete. But this method will be able to prevent the spalling of high-strength concrete, but makes the decrease of the concrete strength after fire. This study make a comparison between properties of preventing of spalling and remaining compressive strength of concrete using intumescence Alkali-Silicates fire-resistant material and that of concrete with organic fibers. Using organic fibers for preventing of spalling of concrete are P.P and Nylon fibers, and anti-fire intumescence material for protection of concrete surface is alkali-silicate materials. Fire resistance test executed as long as 3 hr under the flame temperature $1,200^{\circ}C$ over. In the case of concrete with P.P fibers, don't occurred the spalling, but the remaining compressive strength will not be able to measure, the concrete using intumescence Alkali-Silicates system fire-resistant material is not only preventing of the spalling but also the remaining compressive strength maintained until the maximum 96%.

• Fire Science and Engineering
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• v.33 no.1
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• pp.69-75
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• 2019

In this study, the combustibility of five types of plastic plates, fiber reinforced plastic (FRP), polystyrene (PS), polycarbonate (PC), polypropylene (PP), and polyvinyl chloride (PVC), were tested using a cone calorimeter (ISO 5660). The PVC plate showed a $44.65kW/m^2$ lower peak heat release rate (HRR) and a $30.97kW/m^2$ lower maximum average rate of heat emission than the other four types of plastics, whereas the PS plate showed a $773.44kW/m^2$ higher peak HRR and $399.14kW/m^2$ higher maximum average rate of heat emission. The PC plate and PS plate showed the highest HRR by a maximum of 3.88 times in $CO_{mean}$ yields, while the PS pate and PP plate showed the highest HRR by a maximum 4.88 times in $CO_{2mean}$ yields. In addition, the smoke performance index (SPI) of the PS plate decreased by 74.81%~95.99%; the smoke growth index (SGI) increased to 76%~300%; the smoke intensity (SI) also increased to 917.73% ~ 9607.57%, and the danger of smoke increased. The PS plate was found to have the highest risk of life damage due to smoke on the thermal and smoke sides.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.331-341
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• 2015

The main purpose of this study is reducing the cost and effort for characterization of tensile strength of fiber reinforced concrete, in order to use in structural design. For this purpose, in this study, test for fiber reinforced concrete was carried out. Because fiber reinforced concrete is consisted of diverse material, it is hard to define the correlation between mix proportions and strength. Therefore, compressive strength test and tensile strength test were carried out for the range of smaller than 100 MPa of compressive strength and 0.25~1% of steel fiber volume fraction. as a results of test, two types of tensile strength were highly affected by compressive strength of concrete. However, increase rate of tensile strength was decreased with increase of compressive strength. Increase rate of tensile strength was decreased with increase of fiber volume fraction. Database was constructed using previous research data. Because estimation equations for tensile strength of fiber reinforced concrete should be multiple variable function, linear regression is hard to apply. Therefore, in this study, we decided to use the ANN(Artificial Neural Network). ANN was constructed using multiple layer perceptron architecture. Sigmoid function was used as transfer function and back propagation training method was used. As a results of prediction using artificial neural network, predicted values of test data and previous research which was randomly selected were well agreed with each other. And the main effective parameters are water-cement ratio and fiber volume fraction.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.76-83
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• 2021

This study examines the bending behavior of lap-spliced ultra-high-strength fiber-reinforced concrete members and evaluates the safety of the design codes for ultra-high-strength fiber-reinforced concrete structures. An experiment on a total of six beams was performed. The main variables were the fiber-inclusion and the lap-spliced length at the center of the beams. The steel fibers in a volume fraction of 2% were used, and the lap-splice lengths were determined to be 8db and 16db. As a result of the test, the specimens not reinforced with fiber lost abrupt load-bearing capacity at the lap region and did not experience yielding of the reinforcing bar. In the case of fiber-reinforced concrete, if a lap-splice length of 16db is secured, the yielding of the main reinforcing bar can be experienced, and appropriate flexural strength can be expressed. Based on the experimental results of this study, as a result of reviewing the lap-splice length calculation formulas of the current design standards and the ultra-high-strength concrete structural design recommendations, it was found that all of them were evaluated conservatively.

• Journal of the Korea Concrete Institute
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• v.27 no.5
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• pp.521-530
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• 2015

Design of fiber reinforced ultra-high strength concrete members should be verified with analytical or experimental methods for safety. Members with compressive strength larger than limitation of current design code usually be designed with analytical verification using stress-strain relation of concrete and reinforcements. For this purpose, mechanical characteristics of steel fiber reinforced ultra-high strength concrete were defined under uniaxial compression. Mix proportions of test specimens were based on reactive powder concrete and straight steel fibers were mixed with different volume fraction. Compressive strength of matrix were distributed from 80 MPa to 200 MPa. Effect of fiber inclusion were investigated : increase of compressive strength of concrete, elastic modulus and strain corresponding to peak stress. For the wide range application of investigation, previously tested test specimens were collected and used for investigation and estimation equation. Based on the investigation and evaluation of previous research results and estimation equation of mechanical characteristics of concrete, regression equations were suggested.