• 한국세라믹학회지
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• 제39권10호
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• pp.963-969
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• 2002

본 연구에서는 수중불분리혼화제로서 메칠셀룰로스계를 사용하였고 자체 개발한 멜라민유동화제의 수중불분리콘크리트에 대한 사용량을 5, 7, 9, 11 kg/$m^3$으로 첨가량을 달리하여 slump folw, flow loss, 응결사간, 탁도 및 pH, 압축강도, 수중/기중 압축강도비를 실험한 결과 수중불분리콘크리트의 물성이나 경제성등을 고려할 때 수중불분리콘크리트에서의 멜라민유동화제의 사용량은 약 9 kg/$m^3$인 것으로 나타났다.

• 콘크리트학회논문집
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• 제11권4호
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• pp.21-29
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• 1999

In this study, an experiment was performed to analyze the influence of water-cement ratio on the fundamental characteristics of antiwashout underwater concrete using blended sand (sea sand:river sand = 1:1). The water-cement ratio (45%, 50%, 55%, 60%), andtiwashout underwater agent contents (0.82%, 1.00%, 1.14% of water contents per unit volume of concrete), and superplasticizer contents (1.5%, 2.0%, 2.5% of cement contents per unit volume of concrete) were chosen as the experimental parameters. The experimental results show that the underwater segregation resistance, unit weight of hardening concrete and compressive strength were increased as the water-cement ratio decreased and as the antiwashout underwater agent contents increased. On the other hand, the flowability(slump flow) was increased to the 55% of the increase of water-cement ratio, however, it was decreased at the ratio of 60%. From this study, the antiwashout underwater concrete can potentially be used as a materials underwater work of ocean if the water-cement ratio and chemical admixture contents for the suitable balance between cost and performance are properly selected.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 봄 학술발표회 논문집
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• pp.1-7
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• 1995

The objective of this experimental investigation was to examine the fundamental properties of antiwashout underwater concrete. Expriments were conducted on the antiwashout property in underwater, the compressive strength in the air and in underwater, setting time, slump flow loss. As a result, a dosage of 2.0-2.5kg/$\textrm{m}^3$ antiwashout admixture was found to be appropriate not to cause water pollution and to provide a reliably good compressive strength in underwater concrete. Also, the experimental results showed that the amount of less than 50mg/$\ell$ suspended solid was required to obtain the underwater to air compressive strength ratio of more than 80%

• 한국해양공학회지
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• 제22권4호
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• pp.40-45
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• 2008

This paper describes the effects of fly ash replacement on the water tightness of antiwashout underwater concrete, which replaced the cement with fly ash from 0% to 30%. The experimental work was performed to find out the depth of permeation of concrete specimens cast in air and cured in 23 $^{\circ}C$ tap water using an open center pressure type of water permeation tester. The results showed that the permeation depth values of antiwashout underwater concrete were deeper than normal concrete, but that an admixture using fly ash during antiwashout underwater concrete casting in air made it more watertight than normal concrete according to the water permeation testing. SEM observations of the specimens of fly ash antiwashout underwater concrete showed that it wasmore packed with structures because of the pozzolan reaction of the fly ash and cement.

• 한국산학기술학회논문지
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• 제13권8호
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• pp.3704-3712
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• 2012

최근, 장대교량의 해상기초 구조물에 수중불분리성 콘크리트의 사용이 증가되고 있다. 그러나, 해상기초 구조물에 사용되는 수중불분리성 콘크리트의 공사기간을 단축시키기 위해서는 이전의 수중불분리성 콘크리트보다 유동성을 크게 개선시키는 고유동 수중불분리성 콘크리트의 제조가 필요하다. 따라서 본 연구의 목적은 해상기초 구조물에 사용되는 고유동 수중불분리성 콘크리트의 최적배합비를 도출하는 것이다. 이를 위하여 단위결합재량 550, 600kg/$m^3$ 각각에 대해서 수중불분리성 혼화제 첨가량별로 고로슬래그 미분말을 혼입한 콘크리트를 제작하였다. 제작된 콘크리트의 슬럼프 플로, 응결시간, 수중분리저항성 및 압축강도 비와 같은 품질성능을 관련 규격에 따라 평가하였다. 결국, 고로슬래그 미분말을 혼입한 고유동 수중불분리성 콘크리트는 관련 규격을 만족시키는 수중불분리성 혼화제의 최소 첨가량이 필요한 것으로 나타났다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.345-350
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• 2000

The objective of this study makes investigation into the effect on the properties of underwater antiwashout concrete. which is followed by mixing time and mixing quantity. There is an tendency that (the compressive strength of underwater antiwashout concrete made and cured in fresh water or sea water) is increase when dry mixing time, mixing quantity, total mixing time is increase as unit weight grows. The difference of compressive strength (in case of no dry mixing time and 60 second) is averagely 46.8kgf/㎠ in the fresh water and 35.6kgf/㎠ in sea water. it's considered that dry mixing is dispersed by underwater antiwashout admixture.

• 한국해양공학회지
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• 제25권3호
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• pp.40-46
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• 2011

This paper describes the effects of fly ash replacement on the sulfate resistance of antiwashout underwater concrete which was replaced cement by fly ash from 0% to 50%. and the experimental works were performed on sulfate acceleration test of 5%$Na_2SO_4$ solution to find out the variance of length and weight of specimens. The experimental result shows that the length of specimens of antiwashout underwater concrete age at 180day was highly increased compare with normal concrete by acceleration test. but the mixture which was replaced 50% of fly ash shows reduction of the expansion, weight various, compare with normal concrete specimen. accordingly by using fly ash as admixture in antiwashout underwater concrete in sea environment, it will makes more durable for the attacks of sulfate by sea water.

• 한국해양공학회지
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• 제12권1호
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• pp.153-161
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• 1998

This paper is to investigate the Fluidity of Antiwashout Underwater Concrete containing Fly Ash. The results of study are concluded as follows: the increase in Slump Flow value did not happen in the plain concrete which was replaced cement by Fly Ash; however, the maximum value could reach in the replacement of 30% of Fly Ash by weight of cement in the Fly Ash replaced concrete. On the condition of Fly Ash-Antiwashout Underwater Concrete in expecting 50 cm of the Slump Flow, it was necessary that the usage amount of Superplasticizer be around 1% of unit Binder, and 1.5% in 60 cm of the Slump Flow, respoectively.

• 콘크리트학회논문집
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• 제14권3호
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• pp.409-419
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• 2002

Nowadays, antiwashout underwater concrete is widely used for constructing underwater concrete structures but they, especially placed in marine environment, can be easily attacked by chemical ions such as SO$\^$2-/$\_$4/ Cl$\^$-/ and Mg$\^$2＋/, so the quality and capability of concrete structures go down. In this paper, to solve and improve those matters, flyash and GGBFS(ground granulated blast furnace slag) were used as partial replacements for ordinary portland cement. As results of experiments for fundamental properties of antiwashout underwater concrete containing 10, 20, 30％ of flyash and 40, 50, 60 ％ of GGBFS respectively, setting time, air contents, suspended solids and pH value were satisfied with the "Standard Specification of Antiwashout Admixtures for Concrete" prescribed by KSCE, and also slump flow, efflux time and elevation of head were more improved than that of control concrete. From the compressive strength test, it was revealed that the antiwashout underwater concrete containing mineral admixtures(flyash and GGBFS) is more effective for long term compressive strength than control concrete. An attempt to know how durable when they are under chemical attack has also been done by immersing in chemical solutions that were x2 artificial seawater, 5 ％ sulphuric acid solution, 10％, sodium sulfate solution and 10％ calcium chloride solution. After immersion test for 91days, XRD analysis was carried out to investigate the reactants between cement hydrates and chemical ions and some crystalline such as gypsum ettringite and Fridel′s salt were confirmed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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• pp.324-329
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• 1998

Recently the use of the underwater concrete with the antiwashout admixture is increased considerably. When we intend to apply it to the field, we must consider the water temperature effect. In this study, we investigate the properties of setting time, early strength, hydration temperature history and core strength with the antiwashout underwater concrete in the water temperature 8$^{\circ}C$, 14$^{\circ}C$ and 22$^{\circ}C$ respectively. As a result of experiment, as the water temperature is decreasing, setting time is delayed twice of three times and early strength is lower from 10% to 50%. Therefore to compensate the decrease of the early strength, we used the accelerator and investigated the concrete properties.