• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.381-384
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• 2008

This study investigated spalling prevention and fire resistance properties of the high strength concrete using pre-mixed cement containing fiber to prepare the method for the effective throwing of hybrid fiber. For result of a fire test, almost specimens were protected from fire except 15% of W/C. Totally, the pre-mixed cement containing fiber was favorable compared with passive mixing method for the spalling prevention. It is more effective to prevent spalling caused by fine diversion of fiber even in high strength concrete because it contained many corporate materials. Moreover, the temperature history of the side steel bar on the column test with pre-mixed cement containing fiber did not over 538$^{\circ}C$ which is the average for the standard of fire resistance performance.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.377-380
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• 2008

The material and mechanical properties in the high temperature area of 40 to 100 MPa high strength concrete structural member was identified based on mixing of fiber cocktail and the structural element fire behavior simulation through the finite element analysis method (ABAQUS) was interpreted. The results are as follows. First, it was interpreted that the test specimen with concrete fiber cocktail mixed was more controllable in the maximum shrinkage than the one with concrete fiber cocktail not mixed the controllable range was about 25% to 55%. This means that shrinkage is controllable through mixing of fiber cocktail for the high strength concrete columns. Second, this study didn't consider the explosive spalling by the pore pressure within high strength concrete. If the properties for the pore pressure within high strength concrete is considered and database by strength and by inner temperature of various high strength concrete and steel materials are established in the future, it is interpreted that the technical foundation will be laid for performance based design of fire resistant construction.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.341-344
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• 2004

In the present research, slump, modulus of rupture (MOR) and flexural toughness $(I_{30})$ of high performance hybrid fiber reinforced concrete (HPHFRC) mixed with micro-fiber (carbon fiber) and macro-fiber (steel fiber) and replaced with silica fume were assessed with the analysis of variance (ANOVA). Steel fiber was a considerable significant factor in aspect of the response values of MOR and boo Based on the significance of factors related to response values from ANOVA, following assessments were available; Slump decrease: carbon fiber >> steel fiber > silica fume; MOR: steel fiber > silica fume > carbon fiber; $I_{30}$: steel fiber > carbon fiber > silica fume. Steel fiber $1.0\%$, carbon fiber $0.25\%$ and silica fume $5.0\%$, and Steel fiber $1.0\%$, carbon fiber $0.25\%$ and silica fume $2.5\%$ were obtained as the most optimum mixture.

• Journal of the Korea Institute of Building Construction
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• v.8 no.5
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• pp.53-58
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• 2008

This study is to investigate experimentally residual strength properties of the high strength concrete containing the hybrid of nylon and polypropylene fiber at elevated temperature. Test results showed that specimens heated up to $300^{\circ}C$ exhibited similar strength properties to the one at room temperature. This result is significantly different from previous studies. but specimens heated over $400^{\circ}C$ showed dramatic decrease indicating similar tendency. For the residual strength properties, one at $300^{\circ}C$ even increased 10%, which is also different from previous studies, but it significantly decreased in $400^{\circ}C$ as widely expected. Melted pores by organic fibers in concrete specimens was observed with FE-SEM. For the density of concrete in elevated temperature, internal system in $200^{\circ}C$ had even denser than in $20^{\circ}C$, but was collapsed in $400^{\circ}C$.

• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.265-273
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• 2009

There have been numerous studies to develop eco-friendly concrete. The attempt to reduce the amount of cement used is suggested as one of the solutions for eco-friendly concrete. To decrease the usage of cement, the pozzolan reaction materials are used as a mineral admixture. Hwang-toh, which is broadly deposited in Korea is a well known environment friendly material and the activated hwang-toh, which has the property of pozzolan reaction, is alternatively used as a mineral admixture of concrete. The purpose of this study is to investigate the drying shrinkage of hwang-toh concrete mixed with recycled PET fiber. Therefore, drying shrinkage experiments are performed to analyze mechanical property of hwang-toh concrete mixed with recycled PET fiber. Test results showed that the drying shrinkage is controlled by hwang-toh admixture and PET fiber.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.243-244
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• 2009

Fibers reinforced concrete(FRC) has abilities to make up for brittleness fracture as one of the material characteristics of concrete. However, being mixed with steed fibers in concrete mixes could set off a "Fiber Ball". The Fiber ball formation could be one of the main reasons to decrease the quality of Fibers reinforced concrete. In order to eliminate the fiber ball formation and improve the deficient flowablitiy, The necessity of research for fiber reinforced self-compacting concrete(FRC-SCC) should be raised.

• Magazine of the Korean Society of Agricultural Engineers
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• v.27 no.2
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• pp.47-56
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• 1985

Wasting fiberous residues from the cutting processes of steel materials at an iron-Works were mixed with concrete. The strength and toughness of steel fiber concrete with different steel contents were tested in a laboratory. The test results showed that the steel fiber residues can be used for the reinforcement of concrete. The potential applications of such product include floor constructions for facilities like dairy barns, grain storages, and machinery shops. The test results are as follows. 1. The compressive strengths of steel fiber concrete with one percent steel content by volume were 20 percent greater than that of plain concrete. The treatments also increased the concrete toughness by 96 percent. 2. When applied to tensile forces, the steel fiber concrete showed the increased strengths by 20 percent, and the toughness by 48 percent. 3. The steel content levels greater than or equal to 1.5 percent by volume resulted in the decreases of the compressive and tensile strengths of steel fiber concrete by 10 percent as compared to plain concrete. The concrete toughness increased with the steel contents. 4. The reinforcement effects of steel fiber depend on the quality of fiber material being used. Good steel fiber for concrete reinforcement appears to be uniform in shape and component, fine and long, and round-shaped.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.51-52
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• 2015

In this study, the concrete in which the hybrid fiber with different volume and rate was intermixed in high fluidity concrete. However, Fiber Ball is frequently caused by the decrease in the dispersion of the fiber. The research has been conducted primarily study of single fiber or hybrid fiber, such as different length of single fiber. Therefore, we investigate the mechanical properties of concrete was mixed with a combination of various fibers been produced domestically. Its purpose being to provide basic data for evaluating the impact hybrid fibers on the fluidity of concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.82-83
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• 2015

Recently, the research on steel fiber reinforced concrete has been actively conducted to compensate the defect of brittle fracture of concrete and to enhance toughness. Therefore, the effect of the mixture rate of straight steel fiber on flexural behavior of high strength steel fiber reinforced concrete was evaluated in this research. As a result, when 2% of steel fiber was mixed with concrete volume ratio, it showed the best flexural capacity.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.581-584
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• 2006

This study is analyzed mechanical properties and durability of permeability porous concrete to mix polymer and steel fiber for the enhance of performance and durability of porous concrete. It proves that void ratio and permeability are tallied with internal and external standard of paving porous concrete. A property of strength is increased according as the mixing rate of polymer and steel fiber increase, but it showed the tendency to be reduced on the contrary when mixed upwards of 20% of polymer mixing rate and 0.9vol.% of steel fiber mixing rate. As a result, it is possible to make an enhanced which increased 16% of compressive strength and 30% of flexural strength steel fiber reinforced polymer porous concrete at the mixing rate of 10vol.% of polymer and 0.6% of steel fiber.