• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.533-536
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• 2003

The objective of in this study makes investigation into the characteristics of antiwashout underwater concrete as to mix proportion, casting and curing water through experimental researches. in this study, sea sand is blended with river sand, crushed sand is blended with river sand and sea sand as to investigate the quality change and characteristics of antiwashout underwater concrete with variation of blend ratio of sea sand and crushed sand(0, 20, 40, 60, 80, 100%). Higher compressive strength is measured following the order of river sand, sea sand, crushed sand regardless of age and casting condition. Except for case of using river sand, blended ratio of 40% is appeared on most compressive strength.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.199-200
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• 2010

This paper was estimated the diffusion coefficient through the chlorine ion diffusion coefficient of the high fluidity concrete using the limestone powder. Also, the micro void of high fluidity concrete examined according to the mixing ratio of the limestone powder by the mercury intrusion porosimetry.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.297-298
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• 2010

This study was investigates to the lightweight foamed concrete are uses by foamed agent to hydrogen peroxide($H_2O_2$). and then, lightweight foamed to improve the physical characteristics were mixed. mixes to type of admixture/level by changes/character to investigates, It is a purpose to look up admixture and mix proportion to be suitable in order to improve lightweight foamed concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.430-435
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• 1997

This paper presents the material properties and production of 1400kg/$\textrm{cm}^2$ ultra high-strength concrete in consideration of the history of hydration temperature for the practical utilization. A series of laboratory tests were conducted to optimize the mix proportion and then the full-scall mock up tests were performed to investigate the practicability. The thermal sensors were installed prior to concrete casting into the walls and columns, to measure the hydration temperature during the hardening process, which is inevitable to select the most appropriate curing scheme.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.775-780
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• 2003

The propose of this study is to discover concrete secondary products for proper mixing by lightweight concrete. The standard of water ratio 50% and weight substition 0%, 10%, 20% by Fly-ash. When produce manufactures, there use for maintain its form weight substition and addition among the viscosity agent each Silica-fume and Hydroxy propyl methyl cellulos. Testing method was to operate slump, air content, compressive strength test, rapid freezing and thawing test. The result of this study is appeared when substition Fly-ash generally it had better use Silica-fume.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.313-318
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• 1999

This study is basic research to improve quality of asphalt concrete mixture, to preserve environment, and to recycle waste vinly. The mixing method and proper content of waste vinyl were determined through preliminary mix design. This study performed mix designs using 2 type gradations of aggregate in addtion content of wate vinly. Marshall stability at optimum asphalt content of asphalt concrete mixture addtin wate vinly was satisfied with the specification of the Ministry of Construction and Transportation , and its values indicated that dense grade asphalt concrete mixture containing waste vinyl were higher than common dense grade mixture (control). From this study, it was confirmed that addtion of waste vinyl improved quality of asphalt concrete mixture.

• Magazine of the Korean Society of Agricultural Engineers
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• v.18 no.4
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• pp.4265-4273
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• 1976

1. Fine aggregates of concrete are very important for the construction works and construction cost determination. Most of fine aggregates are from the river sand, but the amount of storage in the river side is steadily decreasing due to continuous construction works. Therefore, another source of fine aggregates is needed to meet increasied demand of sand. 2. Beach sand is a possible source of fine aggregates. But rust of steel bar is caused by CL-chemical of beach sand. Therefore, desalinization of beach sand is requested to get durable reinforced concrete. Economical methods of desalinization are as follows. (a) Flooding and drainage method. (b) Washing of beach sand with water supply and mixing. (c) Spreading of beach sand on the land and leaching by rain water for a few month. 3. Hardening of concrete with beach sand is accelerated due to salt, Thus early stage strength increase leads to make cracks. Also later stage strength decreases and durability becomes worse. By using appropriate admixture, the quality of concrete can be improved.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.266-270
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• 1996

The objective of this study is to develop the Non-compacting concrete with mormal strength in practice by using viscosity agent and flyash. In this paper, we present the reference data about not only the properties of Non-compacting concrete at fresh state such as flowability, segregation-resistibility, placebility and so on but, optimum mixing design using viscosity agent and flyash. The test results indicate that optimum dosage of viscosity agent in combination of flyash in 50% of W/C is about 400g/$\textrm{m}^3$ with 20% of the ratio of flyash replacement.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.521-526
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• 1997

The Spin Tester(High Speed Balancing and Overspeed Test Facility), which is designed for the quality control of turbine, generator, and rotors was supposed to be constructed with the use of Steel Fiber Reinforced Concrete(SERC) for reducing the risk of accident while operation. However, it was very existence of fiber concrete due to there are two major concern in the SFRC work: one is existence of fiber ball due to inhomogeneous mixing, the other is the segregation of the concrete materials. To avoid these possible problems, the S/a was controlled about 55% to reduce the segregation and the high range AE water reducing agent was used to maintain the slump over the value of 18cm. With these careful consideratons, the SFRC work was done successfully by only using regular equipments like pump car and vibrator.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.193-196
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• 2005

In this study, the purpose is to suggest the data on mixing ratio which effects on the carbonation of concrete by replacing various admixture such as silica fume, fly ash, slag powder. Thus, we have experimented the accelerated test on the carbonation related to hardened body of the concrete which was admixed by slag powder, silica fume, fly ash and it was cured for 4 weeks in carbonation accelerator after 28 days curing water. The result of this experiment showed that carbonation speed increased highly when admixtures be used to replacing by growing of admixture ratio. especially, the test sample which was replaced with silica fume 15$\%$ and slag powder 40$\%$, was promoted highly to carbonation.