• Journal of the Korea Concrete Institute
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• v.26 no.5
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• pp.591-598
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• 2014

In this study, the relationship between compressive strength and water-cement ratio according to water reducing ratio was evaluated, concrete mix was prepared according to 3 level of water reducing ratio (0%, 8% and 16%) and 3 level of water-cement ratio (40%, 45% and 50%). In addition, concrete mix was carried out repetition test of three times in order to secure the reliability. As a result, compressive strength according to water reducing ratio was shown that difference of strength was about 20% occurred, effect of compressive strength according to water reducing ratio was found more than the water-cement ratio. Therefore, reflected the effect of water reducing ratio, relationship equation between new compressive strength and water-cement ratio was proposed.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.157-160
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• 2006

Recently, trouble of sand supply is occurred according to exhaustion of natural sand resources. To solve this problem, sea sand and crushed sand are used. But, necessity of water reducing agent because quality of concrete that use sea sand and crushed sand is deteriorated. Therefore in this study was examined on the engineering properties of concrete with kind of fine aggregate and addition ratio of water reducing agents. As a result, compressive strength appeared similar standard regardless of kind of fine aggregate. Compressive strength, durability was similar in decrease of the unit water content by increase of addition ratio of the water reducing agent. Also, drying shrinkage resistivity was improved because the unit water content decreased.

• Food Science and Preservation
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• v.8 no.2
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• pp.157-163
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• 2001

Optimal conditions for hot water extraction of Liriope spicata tuber were investigated with changes in solvent ratio(2∼6 fold) and heating time(1∼5 hr) by response surface methodology. The content of extractable solids increased with an increased in solvent ratio, and the highest content showed at heating time of 3 hr. The content of total steroid saponin increased with a decrease in solvent ratio, and increased with an increase in heating time at increasing the solvent ratio. The content of non-reducing sugar containing oligosaccharides at a lower solvent ratio didn’t show changes depending on heating time, while that at a higher ration decreased with an increase in heating time. Optimal extraction conditions using hot water as the limited conditions of 15∼18% extractable solids, 1.5∼2.0% total steroid saponin, 6∼8% reducing sugar, 6∼7% non-reducing sugar and 13∼15 brix were 3 hrs of heating time and 4 fold of solvent ratio.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.75-78
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• 2003

This study is to investigate the probability to develop the AE Water-reducing agent which can decrease the bleeding by mixing melamine type super-plasticizer(SP) and methyl cellulose(MC) viscosity agent. According to the result, as the mixing ratio of melamine type SP and MC viscosity agent increases, the bleeding is reduced due to a increase of the air content. When the mixing ratio of melamine type SP and MC viscosity agent is 1:2 and 1;3 at the water content of 165kg/$m^3$ and 175kg/$m^3$ respectively, slump and air content are satisfied and bleeding is reduced to some extent, so this is determined as the mixing ratio of AE water reducing agent for reduction of bleeding. It is prove that the developed AE water reducing agent for reduction of bleeding can reduce the amount of bleeding and prohibit the plastic shrinkage crack by slowing down the bleeding speed. Compressive strength of hardened concrete does not make any difference in comparison with plain concrete.

• Journal of the Korean Ceramic Society
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• v.27 no.7
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• pp.833-840
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• 1990

For the development of multi-functional materials which has water reducing power, air entraining power and waterproofing power as well as blending additive in cement mortar the coal ash was modified with asphalt-stearic acid or asphalt-boiled oil mixtures by mechanical treatment. And the physical properties of cement mortar blended with modified coal ashes were compared with those of the water-tightness-cement mortar and the ordinary-portland-cement mortar added with AE.water reducing agent. The mortar of coalash-blend-cement modified with asphalt-stearic mixture was increased acid about 20% in initial strengths and decreased about 20% in water absorption ratio than those of ordinary coalash-blend-cement. The mortar of coalash-blend-cement modified with asphalt-bolied oil mixture was similar to the cement mortar added with AE.water reducing agent in water reduction ratio, air entraining conents and the initial strengths, also was similar to the water-tightness-cement mortar in water absorption and water permeability ratios.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.156-157
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• 2017

It is possible in the case of the chemical admixtures for concrete currently being used in actual work sites to omit quality evaluation and replace it with the scores of the admixture manufactures; this can create a problem of decline in reliability in quality on the work site. Therefore this study sought to analyze the degree of influence changes in the solid content rate of lignin- and naphthalene-based water-reducing agents have on the fundamental characteristics of cement mortar. The results showed that in fresh mortar, the flow and amount of air decreases with decrease in the solid content ratio. In hardened mortar, the condensation strength had hardly any effect on the use of lignin-based water-reducing agent, but naphthalene-based water-reducing agent increased with the decrease in the solid content ratio.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.11a
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• pp.69-72
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• 2003

This study is intended to investigate the fundamental properties of concrete which AE water reducing agent for reduction of bleeding is used, and the properties of bleeding reduction. According to the results, when the adding ratio of AE water reducing agent for reduction of bleeding increases, a range of normal fluidity and aimed air content arc satisfied, setting time is faster than that of normal AE water reducing agent. And bleeding amount decreases, bleeding speed is highest between 60 and 90 min, and sinking depth increases drastically in 60 min. When, AE water reducing agent for reduction of bleeding is added, compressive strength shows a slight variation by air content, but there is not a large influence by addition of AE water reducing agent for reduction of bleeding. Synthetically, it proves that AE water reducing agent for reduction of bleeding satisfies aimed air content in the range of normal slump and can reduce only bleeding without quality variation of compressive strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.69-72
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• 2003

This study is intended to investigate the fundamental properties of concrete which AE water reducing agent for reduction of bleeding is used, and the properties of bleeding reduction. According to the results, when the adding ratio of AE water reducing agent for reduction of bleeding increases, a range of normal fluidity and aimed air content are satisfied, setting time is faster than that of normal AE water reducing agent. And bleeding amount decreases, bleeding speed is highest between 60 and 90 min, and sinking depth increases drastically in 60 min. When. AE water reducing agent for reduction of bleeding is added, compressive strength shows a slight variation by air content, but there is not a large influence by addition of AE water reducing agent for reduction of bleeding. Synthetically, it proves that AE water reducing agent for reduction of bleeding satisfies aimed air content in the range of normal slump and can reduce only bleeding without quality variation of compressive strength.

• Journal of the Korea Institute of Building Construction
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• v.4 no.1
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• pp.133-140
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• 2004

This study is intended to investigate the properties of bleeding reduction of concrete using AE water reducing agent for the type of bleeding reduction with the replacement admixture. According to the results, when the adding ratio of AE water reducing agent for the type of bleeding reduction increases, a range of normal fluidity and aimed air content are satisfied, setting time is faster than that of normal AE water reducing agent. And bleeding amount decreases, bleeding speed is highest between 60 and 90 min, and sinking depth increases drastically in 50 min. When AE oater reducing agent for the type of bleeding reduction is added, compressive strength shows a slight variation by air content, but there is not a large influence by addition of AE water reducing agent for the type of bleeding reduction. Synthetically, it proves that AE water reducing agent for the type of bleeding reduction satisfies aimed air content in the range of normal slump and can reduce only bleeding without quality variation of compressive strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.11a
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• pp.71-74
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• 2005

The viscosity of high-flowability paste is very high compared to normal concrete for the low water-binder ratio(W/B). Therefore, high-flowability concrete is positively necessary to high-range water reducing agent. High-Flowability paste can make much higher fluidity with no occurrence of segregation, by its higher viscosity and lower yield value than normal concrete. The flowability of high-flowability paste must be evaluated not only by convention consistency test such as slump test but also by the base of the rheological properties of the fresh concrete. The purpose of this study is to analyze the fluidity of high-flowability paste according to the addition ratio of the Melamine Sulphonate high-range water reducing agent.; high-flowability paste is considered as Bingham plastic fluid with the rheology parameters of the plaste viscosity and yield value.