• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.423-424
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• 2010

This study purpose is to develop the high fireproof concrete which applied method of combined fiber mixed with polymer powder and organic fiber which can satisfy flowability and the fire resistance properties for construction of the super tall building. According to the results, in case of polymix it is effective to the reduction of internal temperature rise and spalling resistance so it as fire resistance that is similar to existing fiber cocktail.

• Journal of the Korea Institute of Building Construction
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• v.13 no.5
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• pp.465-473
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• 2013

Concrete is an outstanding material in terms of its impact and blast resistance performance. However, there a limitation of concrete is its risk of collapse due to the brittle failure and spalling. Increasing the thickness of members was used as a method to enhance the protective performance of concrete, despite the resulting inefficient space. To solve this problem, different types of fiber reinforced concrete were developed. Recently, another type of fiber reinforced concrete is also being developed and applied as a material that offers protection against impacts and blasts by increasing the flexural toughness of concrete. In this study, the test was conducted to evaluate the impact resistance performance of fiber reinforced concrete and mortar according to impact of high-velocity projectile. A concrete T-wall was also tested to evaluate its protective performance from fragment by 155mm-thick artillery shell. The test results revealed that improving flexural strength through fiber reinforcement inhibited cracks and spalling of rear, and spalling of front by high-velocity impact. As such, it is expected to improve the protective performance of the T-wall and reduce the thickness of the member.

• Journal of the Korean Ceramic Society
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• v.52 no.4
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• pp.253-263
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• 2015

Ordinary Portland cement is a widely favored construction material because of its good strength and durability and its reasonable price; however, spalling behaviour during fire exposure can be a serious risk that can lead to strength degradation or collapse of a building. Geopolymers, which can be synthesized by mixing aluminosilicate source materials such as metakaolin and fly ash, and alkali activators, are resistant to fire. Because the chemical composition of geopolymers controls the properties of the geopolyers, geopolymers with various Si:Al ratios were synthesized and evaluated as fire resistant construction materials. Rejected fly ash generated from a power plant was quantitatively analyzed and mixed with alkali activators to produce geopolymers having Si:Al ratios of 1.5, 2.0, and 3.5. Compressive strength of the geopolymers was measured at 28 days before and after heating at $900^{\circ}C$. Geopolymers having an Si:Al ratio of 1.5 presented the best fire resistance, with a 44% increase of strength from 29 MPa to 41 MPa after heating. This material also showed the least expansion-shrinkage characteristics. Geopolymer mortar developed no spalling and presented more than a 2 h fire resistance rating at $1,050^{\circ}C$ during the fire testing, with a cold side temperature of $74^{\circ}C$. Geopolymers have high potential as a fire resistant construction material in terms of their increased strength after exposure to fire.

• Journal of the Korea Concrete Institute
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• v.21 no.2
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• pp.179-186
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• 2009

The peculiarity pointed out for high strength concrete is the occurrence of spalling during a fire. Recently, there are many efforts such as development of all types of spalling reducing materials and other innovative materials in various fields. Need is now to examine the adequate mixing proportions of these materials. This study intended to derive experimentally and statistically mix proportions that can represent the basic quality requirements as well as the optimal effects on the fire-resistance for 4 types of functional materials that are metakaolin, waste tire chip, polypropylene fiber and steel fiber. Here, the tests were planned through an optimal test method using an orthogonal array table with 4 parameters and 3 levels. The statistical analysis adopted the response surface analysis method. Results verified mutual complementary contribution between the materials when using a combination of the functional materials selected as parameters for the strengthening of the fire-resistance of 80 MPa-class high strength concrete. Besides, the optimal conditions of the fire-resistance strengthening materials derived through response surface analysis were a volumetric replacement of silica fume by 80% of metakaolin, a volumetric replacement of fine aggregates by 3% of tire waste chip, and an addition of 0.2% of the whole volume by polypropylene fiber without mixing of steel fiber. In such cases, the basic characteristics as well as the fire-resistant characteristics of high strength concrete were also satisfied.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.449-456
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• 2002

Recently, the application of high strength and high performance concrete has been gradually increased as an important construction material for high rise and huge scaled construction. However, high performance concrete has undesirable characteristics of spalling subjected to high temperature due to its dense microstructure content. A spalling by fire brings surface failure and falling off concrete member. It is considered that spalling by fire should be taken into account for the safety of the concrete structure under fire. Therefore, in this paper, tests are carried out using high performance concrete containing polypropylene(PP) fiber in order to improve the fire resistance performance. PP fiber contents and member sizes are varied. According to experimental results, as for the influence of PP fiber contents, all the test specimens without PP fiber show entire failure in W/C of 35％, while they show nearly sound shape except some kinds of surface fracture in W/C of 55％. When PP fiber is contained more than 0.07％, favorable prevention effects of spatting by fire are obtained. As for the effects of test specimens size, it tends to increase the possibilities of spatting by fire as test specimens become larger. And spatting by fire at the edge of test specimens occurs more frequently than at the surface of test specimens. Residual compressive and tensile strength shows 45∼65 ％ of its original strength at W/C of 35％, and 30∼40％ at W/C of 55 ％.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.11a
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• pp.310-315
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• 2008

The objective of design for a post flash-over fire is contain the fire and prevent structural collapse, as necessary to meet the performance requirements. In the post flash-over phase of a fire all of the combustible objects in the compartment are burning and the heat release rate is limited either by the fuel surface area or the available air supply. So for the PBD situations, the process of evaluation method for fire phenomena is very important. It is the aim of this study to investigate and analyze the evaluation method of structural fire resistance in Japan.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.551-554
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• 2005

The durability of concrete is decreased by various deterioration factors such as a crack, spalling, corrosion. Many repair and rehabilitation methods have been introduced to extend service life of RC structure. An application of coating material is one of repair and rehabilitation methods. However, there is a problem due to reduction of bonding strength and damage of coating material in the case of existed coating material. Thus, this paper is aim to investigate the chloride resistance according to application method of coating material which improve the existed problem. According to the results, it is showed that application of coating material reduces diffusion of chloride into concrete. In special, application of MMA polymer showed the best resistance for chloride attack. However, variation of application method and number of times has a minor effect on chloride diffusion.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.3 s.32
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• pp.37-45
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• 2004

Electroless Ni(P) has been widely used for under bump metallization (UBM) of flip chip and surface finish layer in microelectronic packaging because of its excellent solderability, corrosion resistance, uniformity, selective deposition without photo-lithography, and also good diffusion barrier. However, the brittle fracture at solder joints and the spatting of intermetallic compound (IMC) associated with electroless Ni(P) are critical issues for its successful applications. In the present study, the mechanism of IMC spatting and microstructure change of the Ni(P) film were investigated with varying P content in the Ni(P) film (4.6,9, and $13 wt.\%$P). A reaction between Sn penetrated through the channels among $Ni_3Sn_4$ IMCs and the P-rich layer ($Ni_3P$) of the Ni(P) film formed a $Ni_3SnP$ layer. Thickening of the $Ni_3SnP$ layer led to $Ni_3Sn_4$ spatting. After $Ni_3Sn_4$ spatting, the Ni(P) film directly contacted the molten solder and the $Ni_3P$ phase further transformed into a $Ni_2P$ phase. During the crystallization process, some cracks formed in the Ni(P) film to release tensile stress accumulated from volume shrinkage of the film.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2002.05a
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• pp.47-50
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• 2002

This paper presents the results of fire resistance properties of high performance concrete varying with fiber kinds and the size of metal lath in order to verify the validities of fiber on the spatting resistance by fire. Metal lath, glass fiber and carbon fiber are used to confine the concrete. According to test results, plain concrete without lateral confinement and confined concrete with glass fiber and carbon fiber show entire failure after exposed to fire, while confined concrete with metal lath take place in the form of slight surface spatting by fire, which has favorable spatting resistance of concrete. As for the effect of the size of metal lath, when the size of metal lath is more than 1.2mm of thickness, the residual strength of concrete exposed to fire maintains more than 80% of its original strength. However, glass fiber and carbon fiber does not perform desirable spatting resistance by fire due to loss of lateral confinement of fiber exposed to fire caused by melting of fiber and reducing bond strength between concrete and fiber.

• Fire Science and Engineering
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• v.24 no.4
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• pp.33-40
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• 2010

A numerical model considering the vapor pressure and the creep models, in the form of a analytical program, for tracing the behavior of high strength concrete (HSC) members exposed to fire is presented. The two stages, i.e., spalling procedure and fire resistance time, associated with the thermal, moisture flow, creep and structural analysis, for the prediction of fire resistance behavior are explained. The use of the analytical program for tracing the response of HSC member from the initial pre-loading stage to collapse, due to fire, is demonstrated. The validity of the numerical model used in this program is established by comparing the predictions from this program with results from others fire resistance tests. The analytical program can be used to predict the fire resistance of HSC members for any value of the significant parameters, such as load, sectional dimensions, member length, and concrete strength.