• Journal of the Korean Ceramic Society
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• v.12 no.4
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• pp.19-28
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• 1975

In order to obtain the superior refractory setter having better spalling resistance, cordierite was synthesized from domestic raw materials. Raw mixtures were fired between 125$0^{\circ}C$ and 140$0^{\circ}C$, and qualitative determination of crytallization was investigated by x-ray diffraction analysis. The results obtained are as follows; 1) The optimum batch composition of synthesized cordierite is 80.5% of Hadong kaolin (pink), 14% of Kyulsung tromolite talc and 5.5% of magnesia clinker, and the firing temperature is 1375$^{\circ}C$. 2) The composition of the refractory setter which exhibits the best values for the thermal properties is 40% of synthesized cordierite, 30% of kaolin chamotte(contains more than 60% of mullite), and 30% of Japanese clay. 3) The optimum particle size distribution of ternary mixture consists of 50% of coarse articles (3.327-1.168mm), 25% of intermediate particles (1.168-0.208mm) and 25% of fine particles (0.208-0.000mm).

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.419-420
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• 2010

High strength concrete(HSC) is made with Fiber-cocktail to control the spalling of HSC. In this paper, the column is made with PP fiber of $1.5kg/m^3$ and steel fiber of 20, 30, $40kg/m^3$, and the test are observed the temperature of reinforced bars and concrete. The results that increasing of temperature is delay as increase of steel fiber's volume.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2006.04a
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• pp.172-175
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• 2006

Recently, fire resistance of high performance concrete for explosive spatting was issued as high performance concrete was vulnerable to the explosive spatting in initial fire. Therefore, This study is willing to propose fundamental data for quick and accurate diagnosis of deteriorated concrete structure by fire damage with making variable concrete test specimen, exposing high temperature environment, observing the explosive spatting and examining engineering property.

• Proceedings of the Korea Concrete Institute Conference
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• 1991.10a
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• pp.158-161
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• 1991

By applying the newly developed techniques of polymer impregnated concrete (PIC) severely deteriorated and low quality concrete can be restored to an adequate structural material. Early deterioration of concrete causes severe problems for bridge deck concrete, pavement concrete for highways and airports, hydraulic structures and buiilding structures. Deterioration has its orgin in cracks on concrete surface, scaling of spalling due to freezing and thawing, neutralization of concrete, penetrations of water, salt, and calcium chloride. The objective of this study is to develope the new surface impregnants and strengthening techniques for them. It is found that the new impregnants and strengthening techniques developed in this study can retian the charecteristics of the existing concrete and decrease deterioration, and also increase durability, chemical resistance, strength, stiffness and ductility of the existing concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.885-888
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• 2006

Nowaday, High strength concrete(HSC) has been mainly used in high rise building. HSC have superior property as well as improvement in durability compared with ordinary 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. Thus, this study is concerned with experimentally investigation fire resistance of the inorganic fire protection materials at high temperatures up to $800^{\circ}C$. From the test result, developed inorganic binder becomes general that with rising temperature the compressive strength of the material increases in tendency. Therefore, the results indicate that it is possible to fireproof panels, fire protection of materials, etc.

• Korean Journal of Materials Research
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• v.7 no.3
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• pp.203-212
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• 1997

This paper evaluated the feasibility of laser consolidation for improving the properties of the plasma coated layer, Further, the mechanim of the degradation sequence of the chrome carbide layer applied on the turbine blades was postualted. The laser consolidation could be successfully applied for improcing the surface properties of the plasma coated blade, if a proper condition was carefully chosen. The consolidated layer had erosion & corrosion resistance and vond strength superiro to those of the as-plasma coated layer. The properties of the consolidated layer were strongly dependent upon the degree of dilution, especially on the Fe pickup from the substrate. The degradation of the plasma coating layer was thought to be a reault of the repeating action of the solid particle erosion, corrosion penetration through the pores and oxide films formed along the interlayer surface and impact spalling.

• Journal of the Korean Ceramic Society
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• v.56 no.1
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• pp.77-83
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• 2019

MgO-C refractories are used in basic furnaces and steel ladles due to their many desirable properties, such as excellent thermal shock resistance via low thermal expansion, and high thermal conductivity. However, the mechanical and thermal properties of the refractory continuously deteriorate by spalling phenomena and pore generation due to the oxidation of graphite, used as a carbon source, indicating that the characteristics and performance of MgO-C refractories need to be improved by using a new material or composition. In this study, the use of a Hertzian indentation test as a method for determining the damage and fracture behavior of an MgO-C refractory is described. The results highlight that Hertzain indentation tests can be one of the important evaluation tools for quasi-plastic damage accumulation of MgO-C refractories during falling process of scrap metal.

• Journal of the Korea Institute of Building Construction
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• v.20 no.3
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• pp.235-243
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• 2020

In recent years, the use of high-strength concrete has increased with increasing height and enlarging scale of the buildings However, it has been pointed out that the use of high-strength concrete is the most serious problem compared to ordinary concrete in terms of the spalling of concrete cross sections caused by fires. For this reason, fiber cocktail methods, which are made of polypropylene fibers, nylon fibers, etc., are mainly used to improve the fire resistance performance. However, the majority of research on high-strength concrete to which the fiber cocktail method was applied is mainly focused on the effect of reducing spalling, and few studies have investigated and analyzed the effect of micropores produced by melting PP fibers on the long-term durability of high-strength concrete after a fire. Therefore, in this study, the effect of micropores on the depth of carbonation was examined through carbonation tests and microstructure analysis, assuming high-strength concrete to which fiber-mixed construction method was applied, which caused fire damage.

• Journal of the Korea Concrete Institute
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• v.21 no.4
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• pp.465-471
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• 2009

To prevent the explosive spalling of the high strength concrete and control the rise of temperature in the steel rebar during fire, a fiber cocktail method has been proposed simultaneously with the use of polypropylene and steel fiber. After applying the fiber cocktail (polypropylene and steel fibers) into the mixture of high strength concrete with a compressive strength of between 40 and 100 MPa and evaluating the thermal properties at elevated temperatures, the fire test was carried out on structural members in order to evaluate the fire resistance performance. Two column specimens were exposed to the fire without loading for 180 minutes based on the standard curve of ISO-834. No explosive spalling has been observed and the original color of specimen surface was changed to light pinkish grey. The inner temperature of concrete dropped rapidly starting from 60mm deep. After 60 minutes of exposure to the fire, the temperature gradient of fiber cocktail reinforced high strength concrete was measured as 2.2oC/mm, which is approximately 5 times less than that of normal concrete. The final temperatures of steel rebar after 180 minutes of fire test resulted in 488.0oC for corner rebar, 350.9oC for center rebar, and 419.5oC for total mean of steel rebar. The difference of mean temperature between corner and center rebar was 137.1oC The tendency of temperature rise in concrete and steel rebar changed between 100oC and 150oC The cause of decrease in temperature rise was due to the water vaporization in concrete, the lower temperature gradient of the concrete with steel and polypropylene fiber cocktails, the moisture movement toward steel rebars and the moisture clogging.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4A
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• pp.391-398
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• 2010

The fire performance of RC slabs with half-depth precast panel after exposure to the ISO-834 fire standard without loading has been experimentally investigated. During heating, according to the ISO 834 fire curve, concrete spalling was observed for concrete without PP(polypropylene) fibers. No spalling occurred when heating concrete containing PP fibers. The maximum temperature of RC slabs with PP fibers with half-depth precast panel was lower than that of concrete without PP fibers. The ultimate load after cooling of the RC slabs that were not loaded during the furnace tests was evaluated by means of 3 points bending tests. The ultimate load of the RC slabs without PP fibers showed a considerable reduction (around 32.5%) of the ultimate load after cooling if compared with of RC slabs with PP fibers. The ultimate load of the RC slabs with half-depth precast panel with PP fibers is higher than that of a full-depth RC slabs with PP fibers. Also, the addition of PP fibers and the use of half-depth precast panel improve fire resistance.