• 한국주조공학회지
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• 제32권3호
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• pp.127-132
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• 2012

Al-Zn-Mg alloys, being high strength aluminum alloys, have attracted attention as a material of automobile parts that require higher mechanical properties and lightness. Automobile parts with complex shapes are manufactured by low-priced casting method, but Al-Zn-Mg alloys are difficult to cast because of its poor hot cracking, feeding, and fluidity. Thus fluidity experiments on Al-Zn-Mg alloys were conducted for the castability evaluation. The effects of Mg and Zn, representative elements of Al-Zn-Mg alloys, on fluidity were observed. Spiral mold was used for fluidity experiments and the lengths of solidified specimens were measured after melting and gravity casting. Correlation between microstructures and fluidity length based on the alloy composition was considered. According to the experimental results, as the amount of Mg and Zn increased, fluidity decreased. Also, it was confirmed that fluidity change by the variation of Mg composition was greater than that of Zn.

• 한국건축시공학회지
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• 제6권3호
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• pp.75-82
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• 2006

This study investigates the influence of various blending factors on cement paste fluidity and find out the most effective evaluation method of cement paste flow, comparing flow test apparatuses such as ring flow(R-F), flow cone(F-C) and mini slump(M-S). A viscometer also measures the rheology coefficients to secure faithful numerical data. Firstly, series I examines cement paste, affected by several cement products and mineral admixture types in the range of W/B 40%, ordinary fluidity, and W/B 30%, high fluidity. In this series, the three types of cement product depended on companies, are randomly used and the mineral admixture, such as fly ash, blast furnace slag and silica fume, are incorporated in the cement paste, in response to the ratio of 10, 20, to 30%, respectively. In addition, series II studies various chemical admixture types, affecting the cement paste. This series is carried out with manufacturing companies and component types in the range of W/C 30%, high fluidity. For the manufacturing companies, randomly four products are used and for the component types, polycaboxylate, melamine, naphthalene and lignosulfonate type are chosen. Test results showed that in the fluidity test of cement paste considering various types of blending factors, R-F exhibited similar tendency with F-C and M-S. In the analysis of consistency curves measured by viscometer, the fluidity evaluation method using flow test apparatuses was significantly effective, except for the some of the low fluidity specimens. In conclusion of this study, R-F was the most convenient, faithful and effective fluidity evaluation method of cement paste.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1990년도 봄 학술발표회 논문집
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• pp.16-19
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• 1990

The effect of superplasticizers on the fluidity performance in fresh concrete and physical properties in hardened concrete have been analyzed and investigated under mix proportions of water cement ratio of 0.4, 0.6, crushed stone aggregates, and addition rates of superplasticizers of 0.0, 0.5, 1.0 and 1.5 in the practical range. It is the aim of this study to provide the fundamental data on the workability improvement and engineering properties of crushed stone concrete using superplasticizers comparing with conventional concrete for the practical use and research data accumulation of superplastized concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 가을 학술발표회 논문집
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• pp.41-44
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• 1995

The purpose of this study is analyze to the properties of high fluidity concrete(W/C 35~50%) with the dosage of viscosity agent(Hydroxy Propyl Methyl Cellulose ; HPMC ; 15U), From the resuls, flowability was good about 200g/㎥. segregation-resisibility and placeability were good upward 300g/㎥, To synthetic, the dosage of viscosity agent are discovered best in 200~400g/㎥

• 공업화학
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• 제21권4호
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• pp.457-462
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• 2010

비이온계 및 음이온계 콘크리트 유동화제가 시멘트 입자의 젖음성 및 콘크리트 경화물성에 미치는 영향을 조사하였다. 시멘트 입자의 젖음성은 혼화제의 유동화제에 따라서 큰 차이를 보였으며, 용액의 표면에너지가 낮을수록 그리고 시멘트에 대한 젖음성이 좋을수록 콘크리트 몰타르의 유동성 및 압축강도가 높았다. 콘크리트 몰타르 유동성 및 강도는 표면개질 성능이 우수한 비이온계인 카르복실레이트 계의 경우가 시멘트 표면 접촉각이 $13^{\circ}$ 정도로 낮아서 그 성능이 가장 우수하였으며 이온계인 리그닌계, 멜라민계, 나프탈렌계는 시멘트에 대한 표면젖음성이 작아 상대적으로 그 성능이 낮았다. 카르복실 계에 리그닌계를 혼합한 경우에 단독 사용하는 경우보다 젖음성이 더 높고 몰타르의 유동성이 더 좋으며 콘크리트 압축강도가 향상되었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문 발표회
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• pp.9-12
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• 2003

High flowing concrete has not spread whole in the normal concrete structure, because it requires special quality control technique. And recently owing to the lack of natural resources and reinforcement of environmental standard, the construction cost of cement is increased rapidly. Also rem icon industry has gone through various economical difficulty as the manufacture cost of concrete is increased. So, the purpose of this study is to evaluate the qualities of middle fluidity concrete using the fly-ash and portland blast-furnace slag cement in order to decrease the amount of cement and resolve the problem of the quality control of high flowing concrete and the manufacture cost. The results of this study show that it reduce the amount of addition of superplasticizer and develope properties of concrete to the use the fly-ash and portland blast-furnace slag cement.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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• pp.307-312
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• 1998

Recently the study on high flowing concrete which has high workability and Self-compacting is being proceeded actively in the university and corporative laboratory. There are some cases that has been applied to the field. This high flowing concrete has higher fluidity and segregation resistance than Plain of flowing concrete. And it is being focused as a remarkable know-how which can make high-quality concrete and reduction effect of labor force. This properties of high flowing concrete are influenced by the relationship of several factors; binder content, water binder ratio and unit water content. It is the aim of this study to propose reference data at mix design of high flowing concrete, after comparing and analyzing the fluidity and strength properties of high flowing concrete according to water binder content ratio and unit water content.

• International Journal of Concrete Structures and Materials
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• 제6권4호
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• pp.231-237
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• 2012

Recently, it has been difficult to get natural sand for concrete due to an insufficient supply in Korea. Crushed sand was thought as a substitute and previous research has been focused on low fluidity and normal compressive strength (24-30 MPa). Study on high performance concrete using crushed sand is hardly found in Korea. In this study it was investigated that the effect of the crushed sand on fluidity and compressive strength properties of high performance concrete. Blending crushed sand (FM: 3.98) produced in Namyangju, Kyunggido and sea sand (FM: 2.80) produced in Asan bay in Chungnam. The final FMs of fine aggregate were 3.50, 3.23, and 3.08. W/B was set as 0.25 to get high performance. With the test results an analysis of relationship was performed using a statistical program. It was shown that strength property of concrete using crushed aggregate at the very early age or after specific time was mainly affected by strength development properties of binders instead of the crushed sand.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.136-145
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• 1997

The purpose of this study is to develope of alternative adimixture for manufacture of PHC pile(compressive strength above 800kg/$\textrm{cm}^2$). For the investigation, properties of alternative admixture admixed with II-anhydrite and pozollanic fine powders(e.q., Fly-ash, Silica-Fume), the fluidity and viscosity in the cement pastes, the fluidity and compressive strength in mortars at steam curing condition, were respectively examined. Also, properties of compressive strength of concretes with exiting admixture(specimen name SM) and alterantive admixture(specimen name AP) for PHC pile, at steam and standard curing condition, were compared each other. As a result of this experimental study, it was found that specimens admixed with II-anhydrite and pozollanic fine powders had an increase on the fluidity of cement paste and mortar, and compressive strength of mortar and concrete was as good as concrete with SM.

• 한국세라믹학회지
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• 제37권1호
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• pp.70-76
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• 2000

In order to investigate the properties of the blended cement using coarsely ground blasturnace slag blended coements which were substituted from 10 to 70 wt% low Blaine slag powder (2,000 and 3,000 cm2/g) for porland cement clinker were prepared and Cal(OH)2 contents in hydrates hydration heat the fluidity and the compressive strength were measured. As the content of slag was increased the hydration heat and the early strength was decreased and the fluidity of the cement paste was improved. The heat evolution of the cement with 2,000cm2/g slag was lower than that of 3,000 cm2/g slag blended cement. Especially the heat evolution of 60wt% or above slag blended cement was similar to that of belite rich cement.