• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.79-82
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• 2005

This study reports on the structural characteristics of slab-column connections using an ultra-high-strength-fiber-reinforced concrete from new and retrospective data. The parameters investigated were the ' puddling ' of ultra-high-strength-fiber-reinforced concrete and the use of high-strength concrete in the slab. The effects of these parameters on the punching shear capacity, negative moment cracking, and stiffness of the two-way slab specimens are investigated. Furthermore, the ACI Code (2002), the CSA Standard (1994), the BS Standard (1985) and the CEB-FIP Code (1990) predictions are compared to the experimental results obtained from some slab-column connections tested in this experiment and those tested by other investigators. The beneficial effects of the ultra-high-strength-fiber-reinforced concrete puddling and of the use of high-strength concrete are demonstrated. It is also concluded that the punching shear strength of slab-column connections is a function of the flexural reinforcement ratio.

• Advances in concrete construction
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• v.6 no.5
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• pp.527-543
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• 2018

Crack control of precast members is crucial for durability. However, there is no clear provision to check the crack width of precast joints. This study presents an experimental investigation of loop joint details for use in a precast bridge deck system. High strength concrete of 130 MPa was chosen for durability and closer joint spacing. Static tests were conducted to investigate the cracking and ultimate behavior of test specimens. The experimental results indicate that current design codes provide reasonable estimation of the flexural strength and cracking load of precast elements with loop joint of high strength concrete. However, the crack width control of the loop joints with high strength concrete by the current design practices was not appropriate. Some recommendations to improve crack control of the loop joint were derived.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.313-316
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• 2004

In this paper, it was assessed durability of ultra-high strength cementitious composites(UHSCC) with the range of 180MPa of compressive strength through the test method of chloride ion resistance, carbonation, freezing-thawing resistance, permeability. In order to compare with ultra-high strength cementitious composites, normal concrete and high-strength concrete were also tested. As the experimental result, it showed that UHSCC was cleary superior to the durability performance of normal concrete and high-strength concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.69-72
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• 2009

This study reviewed the reduction effect of autogenous shrinkage of high strength mortar by plant edible oils based on existing studies, in an effort to find the method of reducing autogenous shrinkage of high strength concrete. To summarize the results, first as characteristics of fresh mortar, substitution of plant edible oil showed slight reduction in liquidity. Compressive strength was reduce at age of 28 days compared to plain mix regardless of type and substitution ratio. Ratio of change in the length of autogenous shrinkage of high strength mortar by plant oils was found to reduce compared to the plain, and the reduction effect was most satisfactorγ in bean oil.

• Advances in concrete construction
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• v.12 no.5
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• pp.367-375
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• 2021

This study experimentally investigated the improvement of bond strength and durability of concrete containing high volume fly ash. Concrete mixtures made with 0%, 25% and 60% replacement of cement with class F fly ash were prepared. Water-binder ratios ranged from 0.28 to 0.72. The compressive, flexural and pullout bond strength, the resistance to chloride-ion penetration, and the water permeability of concrete were measured and presented. Test results indicate that except for the concretes at early ages, the mechanical properties, bond strength, and the durability-related chloride-ion permeability and water permeability of concrete containing high volume (60% cement replacement) fly ash were obviously superior to the concrete without fly ash at later ages of beyond 56 days. The enhanced bond strength for the high volume fly-ash concrete either with or without steel confinement is a significant finding which might be valuable for the structural application.

• Journal of the Korea Institute of Building Construction
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• v.1 no.2
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• pp.179-184
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• 2001

The most recent building trend is going large, high rise, high strength as overlarge project is developing in domestic construction business. Belite cement has properties like low heat, excellent long term strength, and durability without admixture(fly ash, silica fume). so, Beilte cement is suitable for mass structure which is needed high strength, high fluidity and low heat property. This study is to examine the possibility if site adoption microwave-use early strength estimation method. Based on the existed study related the portland cement, the interrelation between Belite cement and microwave-use early strength estimation method is required. In this study, interrelation between mortar and Evaluating strength estimation method is investigated before the concrete experiment.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.493-498
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• 1998

An experimental investigation was conducted to examine the behavior of high-strength concrete R/C columns subjected to moment, shear and axial load. The test parameters of specimens were the compressive strength of concrete(f'c=250, 516, 600kg/ ㎠), space of lateral reinforcement (20, 30, 37cm) and lateral reinforcement ratio(ρs=2.1, 3.15%). Test results indicated that compressive strength of concrete and lateral reinforcement can significantly affect and alter the behavior of column under inelastic cyclic loadings. Despite of the defaults of high-strength concrete, with increased amount of lateral reinforcement ratio to core concrete and added sub-lateral reinforcement, ductility and strength of RC columns used high-strength concrete can secured.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.603-608
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• 2001

In these days, high-strength steel prevails throughout the construction fields for the benefit of structural and economical aspects. But high-strength steel is used by the simple calculation of flexural capacities for the purpose of reducing flexural reinforcement. So, this paper is mainly focused on the shear behavior of high-strength steel reinforced concrete beams without stirrups comparing with normal-strength steel reinforced concrete beams. Specimens were made and tested with the experimental parameters, such as steel yield strength, reinforcement ratios and minimum shear reinforcement. The main result was that not only area but also the yield strength of flexural reinforcement should be considered to predict the shear capacities of concrete beams.

• Journal of the Korea Concrete Institute
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• v.12 no.2
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• pp.53-62
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• 2000

Under severe lateral loads, ductile moments-resisting reinforced concrete frames will be subjected to large loads and displacements. Thus, large deformation and shear stree are occurred at the beam-column joints which are the most critical region in ductile moments-resisting system. The purpose of this study was to investigate the shear strength of beam-column connection using high strength concrete. Four subassemblies were designed 2/3 scale of read structures and tested. The obtained results are as follows. 1) The transverse beams increase the shear resistance and ductility of joint, 2) The slab was contributed to increase of the flexural capacity of the beam, but was not contributed to increase the joint ductility under cyclic loads. 3) The shear stress factors. given by the ACI code would be modified in evaluating the shear strength of beam-column joints of frame which were constructed with high-strength concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1077-1082
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• 2001

The most recent building trend is going large, high rise, high strength as overlarge project is developing in domestic construction business. Belite cement has properties like low heat, excellent long term strength, and durability without admixture(fly ash, silica fume). so, Belite cement is suitable for mass structure which is needed high strength, high fluidity and low heat property. This study is to examine the possibility of site adoption microwave-use early strength estimation method. Based on the existed study related the portland cement, the interrelation between Belite cement and microwave-use early strength estimation method is required. In this study, interrelation between mortar and Evaluating strength estimation method is investigated before the concrete experiment.