• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.51-56
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• 1998

The purpose of this study is to investigate and analyze the fluidity and rheology property of superplasticizer which is necessary using for high flowing concrete fluidity establishment, by changing the substitutional ratio of 6 kinds, and examined the fluidity and rheology properties as time goes by. In the result of this study, the fluidity and rheology properties are differently found and on the effects of admixture for the fluidity, F type is superior and A type is lower than others. Besides, F type is the mose superior values in the time goings.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.45-50
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• 1998

This study is aimed for investigating the rheology property and fluidity of superplasticizer which is necessary using for high flowing concrete fluidity establishment. Therefore, this study is analysis the rheology property and fluidity by different according temperature and elapsed time. From the results, the fluidity and rheology value were different according temperature. Over 2$0^{\circ}C$, the flow value of A, B, C, D, E type is increased, according as the increase of temperature, but the flow value of F type is decreased.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1993년도 가을 학술발표회 논문집
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• pp.45-50
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• 1993

This paper describes some results of various tests which were carried out with varying the fineness of salg from 6000 to 10000$\textrm{cm}^2$/g and the slag content in cement from 30 to 50wt% for the perpose of utilizing finely ground blast-furnace slag as an ingredient for high-performance concrete. Test for heat of hydration, microstructural and hydration characteristics in paste, and fluidity and compressive strength in mortar were carried out. From these test results, it was found that, by properly determining the content and fineness of the slag, it is possible to manufacture high-performance concrete that has low heat of hydration, high early strength development, fine pore size and a highly densified microstructure.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 가을 학술발표회 논문집
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• pp.256-261
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• 1995

Large-scaling recycling of demolished concrete will concrete will contribute not only to the solution of a growing waste disposal problem, it will also help to consweve natural resoures of sand and gravel and to secure future supply of reasonly priced aggregates for building and other construction purposes within large urban areas. Because recycled aggregate particles consits of substantial amount of relatively soft cement paste component, it is less resistant to mechanical actions. With this view in mind, to obtain a reference data for the development of recycling system and to a basic data the guiedline of recycled aggregate concrete construction and engineering properties of recycled aggregate concrete according to the factors, such as blending ratio of recyced aggregete with the natural aggregate, addition to the factors, such as blending ratio of recycled aggregete with the natural aggregate, addition of flyash, water coment ratio.

• 유변학
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• 제7권1호
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• pp.10-18
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• 1995

Plate/plate 및 Truncated cone/plate 감지부를 이용한 시멘트반죽의 유변학적 특성 을 측정함에 있어 관련된 오차에 대한 실험 및 이론적 분석이 보고된다. 주요인자로는 감지 부 직경과 상하 감지부 사이의 간격이 고려되었다. Cone/plate 감지부의 원추끝을 깍아 간 격의 크기를 늘린 Truncated cone/plate 감지부의 토르크 분포에 대한 이론적 분석결과 원 추 간격이 0.7mm 까지 절단되더라도 8.5%의 오차범위내에서는 cone/plate 감지부의 역할을 수행하는 것으로 판단된다. 실험결과는 샘플주변의 상대습도가 결과에 영향을 끼치고 감지 부의 기하학적 요인에도 매우 민감함을 보여준다. 이결과는 정지시간을 포함한 오랜실험기 간동안 미소변형하에서 유변학적 특성을 연구하는데 도움이 될것으로 판단된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.321-326
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• 1997

Recently, High Range Water Reducing Admixture be used increasingly in other to improve the demanded properties (fluidity, strength, durability etc.) and workability in concrete. These kinds of agent govern quality characteristics (air content, setting time, slump, bleeding etc) by the difference of its dispersing mechanism and performance in manufacture of flowed concrete. Accordingly, in this study, for the purpose of high quality construction in site, the comparative experiment of dispersing ability due to commercially available three types of agent were carried out in paste, mortar and concrete using tow types of cement (I, V). In conclusion, the bleeding reduction by the dispersing ability of agents was verified in the fresh properties of flowed concrete with sea water resistance.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.369-374
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• 1997

This study is the experimental results on the flowing properties of the super flowing concrete (SFC) using limestone (LS), which is to develop the SFC in level of ordinary strength. And this study is described with respect to basic concept, confined water ratio ($\beta_p$) of binder (cement+limestone) in paste, relationship between volume ratio of water-binder (w/b) and addition ratio of superplasticizer in mortar, flowing velocity and funneling time and compressive strength in concrete to replacement ratio of LS. The results of this study is improved to flowing properties in fleshly concrete with increasing replacement ratio of LS. The optimal mixing condition of the SFC using LS in level of ordinary strength is proved W/C 55%, LS 40% and W/C 60%, LS 50%.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.33-38
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• 1997

The reuse of waste concrete amy settle the problems of environmental pollution and critical shortage of good natural aggregate. But recycled aggregate particles consist of substantial amount of relatively soft cement paste component. These aggregates are more porous, and les resistant to mechanical actions than natural aggregate. And the source of supply for manufacturing recycled aggregate is generally composed of different types of original aggregate and strengths of original mortar. The properties of recycled aggregate exhibit a considerable variation due to the properties of original concrete. This paper is an experimental study on the fundamental properties of recycled aggregates sampled from processing plant in the suburbs of TaeJeon.

• KCI Concrete Journal
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• 제13권1호
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• pp.35-41
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• 2001

This paper investigated rheological properties of binder pastes for self-compacting high performance concrete. Six mixtures of self-compacting concrete were initially prepared and tested to estimate self-compacting property. Then, the binder pastes used in self-compacting concrete were tested for rheological properties using a rotary type rheometer. Binder pastes with different water-binder ratios arid flow values were also examined to evaluate their rheological characteristics. The binders were composed of ordinary Portland cement, fly ash, two types of pulverized blast-furnace slag, and limestone powder. The flow curves of binder pastes were obtained by a rotary type rheometer with shear rate control. Slump flow, O-funnel time, box, and L-flow teats were carried out to estimate self-compacting property of concrete. The flow curves of binder pastes for self-compacting concrete had negligible yield stresses and showed an approximately linear behavior at higher shear rates beyond a certain limit. Test results also indicated that the binders incorporating fly ash are more appropriate than the other types of binders in quality control of self-compacting concrete.

• International Journal of Concrete Structures and Materials
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• 제8권4호
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• pp.269-278
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• 2014

When concrete is being transported through a pipe, the lubrication layer is formed at the interface between concrete and the pipe wall and is the major factor facilitating concrete pumping. A possible mechanism that illustrates to the formation of the layer is the shear-induced particle migration and determining the rheological parameters is a paramount factor to simulate the concrete flow in pipe. In this study, numerical simulations considering various rheological models in the shear-induced particle migration were conducted and compared with 170 m full-scale pumping tests. It was found that the multimodal viscosity model representing concrete as a three-phase suspension consisting of cement paste, sand and gravel can accurately simulate the lubrication layer. Moreover, considering the particle shape effects of concrete constituents with increased intrinsic viscosity can more exactly predict the pipe flow of pumped concrete.