• Magazine of the Korea Concrete Institute
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• v.4 no.2
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• pp.119-126
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• 1992

고강도 시멘트 복합체의 유동성 손실을 감소시키기 위한 연구의 일환으로 시멘트계 입자에 대한 고성능감수제의 흡착특성, 현탄액 속에서의 응집특성을 관찰하여 시멘트풀과 모르터의 유동성과 관련시켜 고찰하였다. 본 연구결과 알루미네이트계 화합물이 많이 함유된 보통포틀랜드 시멘트의 흡착률이 가장 크며, 시멘트풀 및 모르처의 유동성 손실이 작았으며 나프탈린계 고성능 감수제가 유동성 손실면에서 얼마간 유리하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.63-68
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• 1998

The fluidity of high flowing concrete can be affected by numerous parameters which characterize either the cement of the admixture. The reactivity of a cement as determined by its chemical composition(especially its $C_3$A content), its fineness and its content in sulfates and alkalies obviously plays a key role in rheology of high flowing concrete in fresh state. Specific properties of high range water reducing AE agent used to enhance the workability of high flowing concrete also exert important influence. The purpose of this experimental study is to investigate and analyze the effect of cement and high range water reducing AE agent in fluidity, setting, compressive strength of high flowing concrete. As a result, we found that fluidity of high flowing concrete is affected greatly by kind of cement and high range water reducing AE agent, also, there is harmonic character between high belite cement and polycarbonic acid high range water reducing AE agent.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.157-160
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• 1998

KS F 4419, which is dealt with the Inter-Locking block, states that water to cement ratio for manufacturing inter-locking block should be less than 25% and in KS F4419, the use of admixture is shown to be reluctant to recommend. In this paper, reinvestigation of some regulations in KS F 4419 are carried out. According to the experimental results, as W/C increases, flexural strength and compressive strength are tended to decrease, whereas they increases within certain range, Flexural strength and compressive strength have higher values in 1:2(W/C=35%), 1:4(W/C=45%) and 1:6(W/C=55%) of mix proportions. Moreover they have rather higher values with the containment of high range AE water-reducing agent. The absorption ratios decrease with the increase of W/C and the containment of high range AE water-reducing agent. Therefore, the regulations on the W/C and admixture in KS F 4419 reguire revision.

• Journal of the Korean Society of Safety
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• v.12 no.1
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• pp.101-107
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• 1997

High strength concrete(HSC) using high range water reducing admixture (HRWR) has the defect which severe slump loss occurs according to elapsed time. For using HSC without any trouble, special caution and countermeasure against this problem are necessary. In this study, for minimizing the slump loss of HSC, mineral admixture( flyash, ground granulated blast furnace slag ) and gypsum were used experimentally. Flyash and ground granulated blast furnace slag are effective in reducing the slump loss of HSC. Especially, the slump loss of HSC containing mineral admixture and gypsum Is minimized by the aggregation inhibiting action of gypsum. Cement substituted with flyash 30% or ground granulated blast furnace slag 50% by weight are very effective in minimizing the slump loss.

• Proceedings of the Korea Concrete Institute Conference
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• 1991.10a
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• pp.21-25
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• 1991

For the purpose of improving the compressive strength of concrete, the high strength concrete which have the compressive strength about 800kg/$\textrm{cm}^2$ were made by using silica fume and high range water reducing admixture on reducing the water-cement ratio. But the facts that the slump loss of high strength concrete was high and the tensile strength and elastic modulus were not improved enough are indicated to problems which must be solved.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.3
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• pp.81-90
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• 1992

This study gives results of 1aboratory investigations to minimize the slump loss of concrete using high range water reducing admixture (HRWR). Various factors influencing on the slump loss such as cement type, HRWR type and dosage time are investigated. The acquired results indicated that 30 minutes delayed dosage of HRWR is very effective on reducing the slump loss though this tendency makes a difference to some extent according to cement and HRWR type. For the most part, the more usage of HRWR increases, the higher the slump loss occurs and concrete using ordinary portland cement has the highest slump loss and concrete using fly ash 20% replacement cement with HRWR of naphthalene type has the good effect on reducing the slump loss.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.10a
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• pp.94-99
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• 1992

In this study , some factors such as mix proportion, type and dosage of high range water reducing admixture(HRWR) and natural pozzolanas influencing on the slump loss of high strength concrete(H.S.C) using HRWR were investigated for reducing the slump loss. The acquired results indicated that the slump loss of H.S.C was affected according to cement content, sand percentage and type and dosage of HRWR and fly ash was superior to ground granulated blast furance slag in reducing the slump loss of H.S.C.

• International Journal of Concrete Structures and Materials
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• v.9 no.2
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• pp.185-206
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• 2015

This paper presents statistical models developed to study the influence of key mix design parameters on the properties of lightweight self-consolidating concrete (LWSCC) with expanded shale (ESH) aggregates. Twenty LWSCC mixtures are designed and tested, where responses (properties) are evaluated to analyze influence of mix design parameters and develop the models. Such responses included slump flow diameter, V-funnel flow time, J-ring flow diameter, J-ring height difference, L-box ratio, filling capacity, sieve segregation, unit weight and compressive strength. The developed models are valid for mixes with 0.30-0.40 water-to-binder ratio, high range water reducing admixture of 0.3-1.2 % (by total content of binder) and total binder content of $410-550kg/m^3$. The models are able to identify the influential mix design parameters and their interactions which can be useful to reduce the test protocol needed for proportioning of LWSCCs. Three industrial class ESH-LWSCC mixtures are developed using statistical models and their performance is validated through test results with good agreement. The developed ESH-LWSCC mixtures are able to satisfy the European EFNARC criteria for self-consolidating concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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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.

• Journal of the Korea Concrete Institute
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• v.26 no.4
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• pp.457-463
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• 2014

The permitted limit, ${\pm}12%$, of the change in solid contents based on ASTM C 494 as an interim standard in Korea Expressway Corporation, can not reflect the kind of chemical admixture and the characteristics of solid content so that it differed depending on the admixture types. In this study, effect of cement concrete quality was investigated by solid changes which can be used chemical admixtures acceptance criteria. As a result of an evaluation of a change in the quality of concrete due to solid content, since Ligno-sulfonate based (LG) had a low water reducing ratio, the range of the change in solid content was great while Naphthalene sulfonated based (PNS) and Poly-carboxylate based (PC) High Range Water-reducing Admixtures (HRWR) had a high water reducing ratio, the permitted limit of the difference in solid content currently used as the acceptance criterion should be readjusted. As a result, it is found that the acceptable range must be managed within 10% and 5% when the solid contents less than 25% and more than 25%, respectively.