• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.683-688
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• 2000

Nowadays, shotcrete plays an essential part in the construction of underground structures, and fiber reinforcement is so useful for increasing the toughness of the concrete that is spotlighted at tunnel or pavement construction. Therefore, many type of fibers have been introduced on the site and variety of tests have been developed to measure and quantify the improvements achievable in fiber reinforced concrete and shotcrete. Therefore, this study focuses on the flexural toughness according to the fiber types and appraisal methods. The major interests are fiber types, volume fractions and evaluation methods.

• Journal of the Korea Concrete Institute
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• v.13 no.2
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• pp.161-167
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• 2001

It is difficult to obtain accurate fracture toughness values using three point bending test(TPB) proposed by RILEM committees because the shape of load-deflection curve is irregular and final crack propagation occurs after some slow stable cracking. However, fracture toughness is easily obtained from crack initiation load in the disk test. In this paper, the fracture properties of high strength concrete disks with center-crack was investigated. For this purpose, the experimental results were compared with the results by finite element analysis(FEA). And the experimental fracture locus was compared with theoretical fracture locus. Also, the results of fracture properties for the degree of concrete strength are presented. It is concluded from this study that results from FEA with maximum stress theory were compared well with the results from experiment. And the degree of concrete strength was contributed to the crack initiation load and fracture toughness, but was not contributed to the failure angle. Also, The discrepancy of fracture locus between the maximum stress theory and the experiment for concrete is considered to depend upon a large energy requirement for inducing the mixed-mode and sliding mode fractures.

• 한국도로학회:학술대회논문집
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• 2009.11a
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• pp.69-72
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• 2009

• Journal of the Korea Institute of Building Construction
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• v.17 no.2
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• pp.167-174
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• 2017

This research investigated the mechanical performance of slurry infiltrated high performance fiber reinforced cementitious composite (SI-HPFRCC) with high volume blast furnace slag powder. Hooked-end steel fibers (volume fraction of 6.4%) were used for the fabrication of SI-HPFRCC. A series of mechanical performance test was conducted including strength and toughness of SI-HPFRCC in compressive and flexural mode at four different ages. Compressive and flexural strength tests of the slurry matrix at the same ages were also conducted in order to evaluate fiber reinforcing effect on the mechanical performance. The flexural response of SI-HPFRCC shows an increasing brittleness with age. The compressive response also shows an increasing brittleness with age but the degree of brittleness is much lower than the flexural case. In terms of strength, SI-HPFRCC shows about 140~190% of compressive strength improvement and 440~500% flexural strength improvement comparing to the slurry matrix.

• International Journal of Highway Engineering
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• v.12 no.1
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• pp.47-54
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• 2010

This study had a focus on investigating technical validity of Two-Lift Concrete Pavements which had never been constructed in Korea in order to olve the problem of existing concrete pavements. This study found out the application of Steel Fiber Reinforced Concrete (SFRC) which was one of ew techniques. Also, optimal steel fiber contents and pavement thickness were determined. This study also measured compressive strengths, lexural strengths, toughness indexes, tensile strengths and fatigue strengths to estimate the performance of SFRC of according to results of aboratory experiments, slumps and air contents of concrete specimens the standards satisfied and compressive strengths to open traffic. At bending ests, Toughness Index of SFRC increased but flexural strength didn’'t increase as compared with non-steel fiber concretes. And, energy absorption of SFRC was very good and SFRC showed improvement in freezing and thawing resistances. To complete this research, we will evaluate the pplication methods and performance of SFRC at field section.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.685-688
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• 2008

Concrete is strong on the compressive property, but weak on the tensile and flexural properties. To improve these problems, the reinforcing bar is used in concrete. But porous concrete with steel fiber has a weak point when exposed to air, because porous concrete has the vast continuous void on its inside and steel fiber is easily rusted by air. For these reasons, this study investigated the void ratio, compressive strength, bending strength and bending toughness as steel fiber mixing ratio and target void ratio. From test results, actual void ratio and strength properties increased as the mixing ratio of steel fiber increase. In case the mixing ratio of steel fiber over the fixed ratio, strength is decreased. And from the toughness evaluation, compared to the porous concrete which isn't mixed with steel fiber, the deflection variation efficiency is remarkably improved. Consequently we can confirm the possibility of porous concrete with steel fiber for the secondary product and pavement material to improve strength and bending resistance efficiency.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6A
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• pp.1033-1039
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• 2006

The purpose of this study are to evaluated bond, flexural properties and control of plastic shrinkage cracking of crimped type synthetic fiber with amplitude 6 mm and height 1.8 mm reinforced cement based composites. Bond and flexural test were conducted in accordance with the JCI-SF 8 and JCI SF-4 standard, respectively. The plastic shrinkage cracking test was conducted for evaluating the effect of fiber in reducing shrinkage cracking in cement based composites. Test results indicated that the crimped typel synthetic fibers performed significantly better than the straight type fiber in terms of interface toughness and pullout load and the crimped type synthetic fibers improved the flexural toughness of concrete. Also, the increasing the crimped type synthetic fiber volume fraction from 0.00% to 1.00% improved the plastic shrinkage cracking resistance. Specially, the effect of control of plastic shrinkage cracking is excellent at the more than 0.5% fibre volume fraction.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.215-216
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• 2023

Leakage in the structure due to the irregular flow of groundwater in the underground structure penetrates into internal spaces such as underground parking lots and basement through underground walls, which is expensive in terms of maintenance of the building. In this study, various composite waterproofing methods installed on the outer walls of underground structures were selected to evaluate the structural performance of composite specimens due to bending behavior through experiments and analysis on bending test behavior on concrete attachment surfaces.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3A
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• pp.401-406
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• 2008

This study can be used to produce structurally efficient recycled PET fiber from used waste PET bottles and evaluated the bond performance of the three type of recycled PET fiber and cement matrix. Also, the flexural tests were performed on concrete reinforced using the three type of recycled PET fibers. The test results showed that the recycled PET fiber was significantly increased bond strength. The flexural test results are demonstrated that recycled PET fibers improved the flexural toughness of concrete. Based on the bond and flexural test results, the bond and flexural performance of embossed type recycled PET fibers were significantly better than those of the other shape fibers.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.437-438
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• 2010

This study was carry out to evaluate the effect of flexural behavior according to using hybrid steel fiber in UHPC. The evaluation of the flexural behavior of UHPC using hybrid fibers showed that the admixing of hybrid steel fibers at a volumic ratio of 2% increased the flexural strength by more than 27% (maximum 50%) compared to the use of steel fibers only. A ratio of 1.5% was seen to provide flexural strength exceeding the current strength of UHPC.