• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.135-138
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• 1999

The objective of this study is to investigate the compressive strength property of antiwashout underwater concrete with curing water through experimental researches. Type of casting and curing water(fresh water, sea water) are used as main experimental parameter, additionally a few variables affecting compressive strength property are used ; water-cement ratio (45%, 48%, 50%, 52%, 55%), and unit weight of admixtures (antiwashout underwater agent ; 0.6%, 0.8%, 1.0%, 1.2%, 1.4% of unit weight of water, superplasticizer ; 0.5%, 1.0%, 1.5%, 2.0%, 2.5% of unit weight of cement)) Compressive strength level of antiwashout underwater concrete which was cast and cured in fresh water is higher than other one. Consequently, incremental modulus has to increase when the antiwashout underwater concrete is made use of underwater work from ocean.

• Journal of the Korea Concrete Institute
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• v.17 no.2 s.86
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• pp.303-309
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• 2005

This study aims the evaluation of the corrosion of steel bar embedded in antiwashout underwater concrete, which has rather been neglected to date. To that goal, accelerated steel bar corrosion tests have been performed on three series of steel bar-reinforced antiwashout underwater concrete specimens manufactured with different admixtures. The three series of antiwashout underwater concrete were: concrete constituted exclusively with ordinary portland cement (OPC), concrete composed of ordinary portland cement mixed with fly-ash in $20\%$ ratio (FA20), and concrete with ground granulated blast furnace slag mixed in $50\%$ ratio (BFS50). The environment of manufacture was in artificial seawater. Measurement results using half-cell potential surveyor showed that, among all the specimens, steel bar in OPC was the first one that exceeded the threshold value proposed by ASTM C 876 with a potential value below -350mv after 14 cycles. And, the corresponding corrosion current density and concentration of water soluble chloride were measured as $30{\mu}A/mm^2$ and $0.258\%$. On the other hand, for the other specimens that are FA20 and BFS50, potential values below -350mV were observed later at 18 and 20 cycles, respectively. Results confirmed the hypothesis that mineral admixtures may be more effective on delay the development of steel bar corrosion in antiwashout underwater concrete.

• Magazine of the Korea Concrete Institute
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• v.8 no.5
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• pp.179-187
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• 1996

Many underwater concrete structures have been constructed recently in proportion to the increase of ocean developments. The research for the underwater concrete construction was mainly focused in view of placing method. Recently, special admixture agents of concrete were developed for antiwashout concrete under water in some foreign nations. They had successful results in experiments and site constructions. However. there are seldom experimental results or placements in domestic contry. In this paper. We had carried out property tests of fresh and hardened concrete with refer to successful results in experiments and site construction and investigated the physical variation of the antiwashout underwater concrete considering the interaction between antiwashout admixture and other ones. We have decided the optimal mix proportion fb;r antiwashout underwater concrete under standerd sea state.

• Journal of the Korea Institute of Building Construction
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• v.3 no.3
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• pp.91-97
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• 2003

At present, the antiwashout underwater concretes are used as popular construction materials in European countries, the United States and Japan. The water-soluble polymers in the antiwashout underwater concretes provide excellent segregation or washout resistance, self-compaction and self-leveling property to the concretes. The purpose of this study is to recommend to optimum mix proportions of antiwashout underwater concretes according to compressive strength of 300kgf/$\textrm{cm}^2$ to 500kgf/$\textrm{cm}^2$. The antiwashout underwater concretes are prepared with various unit cement content, unit water content, sand-aggregate ratio, unit antiwashout agent and superplasticizer content. And they are tested for flowability, and compressive strength. From the test results, it is possible to recommend the optimum mix proportions of antiwashout underwater concretes according to compressive strengths within the range of 300kgf/$\textrm{cm}^2$ to 500kgf/$\textrm{cm}^2$.

• Journal of Ocean Engineering and Technology
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• v.22 no.4
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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.

• Journal of the Korea Concrete Institute
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• v.11 no.5
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• pp.51-60
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• 1999

When placed under water, concrete is diluted with separating cementitious material and as a result the quality of concrete becomes poor. So as to solve the problem, underwater concrete is increasingly used for the construction and repair of the concrete structure under water. In this paper, 4 kinds of antiwashout admixtures and varying sand percentages were chosen to measure the suspended solids, pH, air contents, setting time and compressive strength of underwater concrete, and they meet "Standard for antiwashout admixture used for concrete". When sand percentage is 43%, the fluidity and filling of underwater concrete are superior to the others.he others.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.609-612
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• 1999

Recently, the antiwashout underwater concrete with an antiwashout admixtures has been increasingly used for underwater structures. However, the credibility of antiwashout underwater concrete was brought up as problems because it seldom was applied to fields. In this study, experiments were made on the basic properties of antiwashout underwater concrete replaced with fly ash up to 30% to improve its properties. Resultant to the test, we got the results as follow; funnel flow time was decreased, the slump flow was increased and the elevation of head was decreased rapidly whereas the amount of suspended solids became high, pH became low. In view of 70%, the standard ratio of compressive strengths between cast in water and in air, it was obtained the result that the ratio was over 90% at 28days.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.970-976
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• 2002

In this paper, the slump flow of the concrete, suspension, pH, corrosion effect, bleeding and the characteristics of coompressive strength were analyzed using antiwashout underwater admixture and antiwashout underwater agent+corrosion inhibitor mixed admixtures(1type). The results showed that there were no rare difference in physical properties but in the results of rapid corrosion tests there were lots of corrosion inhibitor ratio differences between concrete using only antiwashout underwater admixture and the corrosion inhibitor mixed(1type). In the case of only antiwashout underwater admixture 5.4%, the case corrosion inhibitor mixed(1type) 0.07%, the Antiseawater of the concrete which uses the Corrosion Inibitor Mixed(1type) appeared highly.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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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%

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.41-46
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• 2000

In recently, though the development of antiwashout admixture, if's possible to construct in underwater with the concrete which is improved segregation resistance of material, filling and self-leveling. It is generally to use this method with Europe and Japan as the central figure, and also the construction case is reported in korea. There's some advantages to add the fly ash in plain concrete. The objective of this study is to find the characteristics of fresh underwater antiwashout concrete which is followed by the blend rate of fly ash.