• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.267-270
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• 1998

Recently, underwater concrete constructions are increasing. Therefore it is considered important to control the quality of underwater concrete. In this paper, we have an intention of evaluating fundamental properties of underwater concrete using the anti-washout admixtures. Thus, it has been investigated that the setting slump flow of the concrete, pH value and suspended solids in solution, compressive strength on both of specimens made above and under water. Also the percentage of fine aggregate has been found to alter the compressive strength in underwater concrete.

• Journal of the Korea Concrete Institute
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• v.11 no.6
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• pp.69-78
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• 1999

Hydroxyethyl cellulose -based-viscosity modifying admixture and melamine-basd-superplasticizer were selected to be admixtures for self-compacting concrete based on the test results of fluidity and air content of mortar using 3 different viscosity modifying admixtures. The experimental results show that the initial and final set of self-compacting concrete and fly ash concrete with viscosity modifying admixture only have been delayed approximately 5 hours and 8~9 hours, respectively. It is found that the optimum dosage of viscosity modifying admixtures, coarse aggregate and cement content are 0.2% of water content, under 742 kg/$\textrm{m}^3$ and over 364 kg/$\textrm{m}^3$, respectively. Test results also show that the optimum fly ash in replacement of cement is 10% of cement weight for the enhancement of fluidity and long-term strength.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.641-646
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• 1998

The structures exposed to marine environment do not show long-term durability due to corrosion of steel and deterioration of concrete by the attack of various salts dissolved in sea water. In this study, Partial substitution of cement with fly ash(20%) or blast furnace slag(40%) was made together with the addition of 4 different corrosion-inhibitors, as a protective measure of concrete structures against chemical attack of salts. Combined effects of mineral and corrosion-inhibiting admixtures were tested by measuring the resistance and compressive strength of concretes under the simulated tidal condition, which consists of alternating 12 hour periods of immersion in artificial sea water and drying in air. Both the strength and concrete resistance were found to decrease in following order, regardless of the corrosion inhibitors the concretes with blast furnace slag, those with fly ash and those without any mineral admixtures. The interrelation between compressive strength of concrete and resistance was investigated.

• Journal of The Korean Digital Architecture Interior Association
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• v.12 no.4
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• pp.87-95
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• 2012

Autoclaved lightweight concrete (ALC), also known as autoclaved aerated concrete (AAC), is a lightweight, precast building material that simultaneously provides structure, insulation. ALC is a unique building material. Because of its cellular nature, it is lightweight, self-insulating, as well as sound and fireproof. ALC products include blocks, wall panels, floor and roof panels, and lintels. Recently, the use of ALC has became increasingly popular. However, ALC have high water absorption, low compressive strength and popout the origin of the low surface strength in its properties. Thus, this study is to improve the fundamental strength by controls of increasing of admixtures and chemical reactants. Admixtures make use of meta kaolin and silica fume, chemical reactants make use of sodium silicate and sodium hydroxide. From the test result, the ALC using admixtures and chemical reactants have a good fundamental properties compared with plain ALC. These good fundamental properties is caused by the admixtures and chemical reactants of ALC by the reason of the micro filling effect and chemical binding of C-S-H gel, tobermolite and quartz.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.783-794
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• 1994

Recently, several failure cases of concrete structures during construction have been reported. The main reason for these failures is attributed to the poor quality of concrete during construction. It is, therefore. necessary to develop and use high quality concrete. The purpose of the present study is to explore the characteristics of superplasticized concrete, especially the effects of mineral admixtures on the fluidity and strength characteristics of high performance concrete. The mineral admixtures considered in the present study are fly ash, blast furnace slag and silica fume, respectively. The major test variables include the amount of these mineral admixtures, cement contents and water-cement ratios. The compressive strengths for various cases were measured and reported. Optimum contents of mineral admixtures for strength development were derived. The corrosion phenomena of reinforcements embedded in various concrete specimens have been also studied. The present study provides useful basis to apply high-performance concrete to actual structures.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.647-650
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• 2001

The purpose of this study was the influence of cold weather ready mixed concrete quality according to needs of customer were investigated by measurements of slump, air content, temperature and compressive strength. As a results, cold weather ready mixed concrete using high standard admixtures, high early strength admixtures and cold weather concrete plant were similarly to slump, air content, temperature and compressive strength.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.83-88
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• 1998

II-anhydrite, slag, and fly ash produced as industrial by-product were reutilized for the manufacture of high strength admixtures for cement and concrete. The effects of these admixtures on the compressive strength of cement mortar and concrete were examined with those of domestic admixture. At the condition mortar and concrete. Especially, adding of II-anhydrite was very effective for the increasing of compressive strength. Therefore it is possible that these admixture as a high strength admixture apply to cement and concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.335-340
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• 1997

The mineral admixtures, ground granulated blast furnace slag (GSB) and fly ash (FA), were mixed with ordinary portland cement(OPC) in order to reduce temperature rise and slump loss in concrete. In according to concrete replaced with 30% of GBS, the compressive strength of that developed to 574 kg/$\textrm{cm}^2$ at age of 28days and maximum temperature decreased to the extent of $5^{\cire}C$. When GBS and FA are mixed with concrete, it can be estimated that mix proportions of them have to be taken into consideration.

• Proceedings of the Korean Institute of Building Construction Conference
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• v.y2004m10
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• pp.51-54
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• 2004

This paper investigated the results of mixture proportion and compressive strength of concrete incorporating mineral admixtures. W/B and contents of mineral admixtures were selected as test parameters. According to test results, use of mineral admixtures resulted in a reduction of fluidity and air contents caused by increased fine particles and absorption effect of FA on reduction of AE agent. Thus, increase of SP and AE agent was needed to maintain the same fluidity and air content as plain concrete. At early stage, use of CKD was beneficial to the compressive strength while at 28days. incorporation of FA and BS had favorable effect on the compressive strength.

• Magazine of the Korea Concrete Institute
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• v.7 no.2
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• pp.155-164
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• 1995

This study was performed to get high strength of the precase concrete adopting a steam curing by using a gypsum-admixture for the high strength concrete. The superplasticizer was used to compensate low slump of base concrete keeping its slump up about $6{\pm}1cm$. To examine the property for strength revelation of concrete using admixtures for a high strength concrete, steam and standard curing were compared each other. Test results were shown that admixtures for high strength concrete were more effective in steam curing than standard curing. On the condition that the unit cement content is about $530{\sim}600kg/m^3$, the compressive strength of concrete replacing by 10% of the admixture was obtained over $65Okgf/cm^2$, which was increased as 1.3 times as that for the nonreplacement. When the admixture was replaced to 15-30%, the compressive strengh was obtained over $700kgf/cm^2$ which was increased as 1.4 - 1.5 times. Therefore, the admixture for high strength concrete, being effective in steam curing, was more efficient to get a high strength concrete using only steam curing instead of an autoclave curing for the secondary products of cement.