• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 추계 학술논문 발표대회 논문집
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• pp.13-16
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• 2006

This study investigates filed application in Daebul Free Trade Zone of a flowing method using drying shrinkage-reducing superplasticizer(SRS) and an insulating curing method using double bubble sheets. Test showed that fresh concrete satisfied target slump and air content. A structure adding SRS significantly decreased the total bleeding capacity and accelerated the setting time. As for the crack occurrence, the structure applying the flowing method and double bubble sheets simultaneously exhibited the most favorable crack endurance, while conventional concrete showed more than 1mm size of crack in overall, and a structure applying only the flowing method partially presented micro crack. For the area proportion of crack occurrence, the structure using the double bubble sheets indicated 9.8%, while others applying flowing method was 28%, compared with 100% of conventional one. Standard curing specimens had about $3{\sim}6%$ higher compressive strength than that of specimens cured at adjacent field construction. In addition, using SRS improved about $5{\sim}7MPa$, than that of conventional concrete at 91 days elapse.

• Computers and Concrete
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• 제6권4호
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• pp.343-356
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• 2009

Experiments were designed to investigate the flow behavior of portland cement paste and concrete incorporating superplasticizers. The paste and concrete mixtures were subjected to prolonged mixing for up to 110 min at high temperature. The yield stress values of concrete and that of the corresponding cement paste were measured using a rotating rheometer and viscometer, respectively. The results reveal a weak linear correlation between the yield stress of concrete mixtures and that of the corresponding cement pastes. Results also indicate that the yield stress of concrete varies in a linear fashion with the elapsed time, while its variations with the temperature and superplasticizer dosage follow power and inverse power functions, respectively. In this study, the genetic algorithms (GA) technique was used to predict the yield stress of concrete considering various parameters, such as the mixing time, ambient temperature, and superplasticizer dosage. A sensitivity study was conducted to evaluate the ability of the GA equations thus developed to capture the effects of test parameters on the yield stress of concrete. It was found that the GA equations were sensitive to the effects of test parameters and provided yield stress predictions that compared well with corresponding experimental data.

• 한국세라믹학회지
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• 제40권3호
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• pp.219-224
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• 2003

Fly ashes containing 6.1~16.5 wt% of unburned carbon were treated thermally at 500$^{\circ}C$ for 3 h and thus, the content of unburned carbon was decreased below 2.1 wt%, the range of particle size distribution became narrower and the mean particle size became smaller. Besides, the properties of particles in fly ashes were improved, particularly the particle shape became close to a spherical type. The fluidity of cement pastes containing fly ashes treated previously at 500$^{\circ}C$ for 3 h was increased much than that of cement pastes containing original fly ashes. When the added amount of superplasticizer was over the saturation amount, there was no correlation between the amount of unburned carbon in fly ashes and the apparent viscosity of cement pastes actually. On the contrary, when the added amount of superplasticizer was below the saturation amount, there was a correlation.

• Advances in concrete construction
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• 제6권6호
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• pp.659-677
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• 2018

The use of some superplasticizers in the production of mortar or concrete influences the hydration kinetic and the amount of total heat. This results in a modification of some properties, namely mortar workability, mechanical strength and durability. Three superplasticizers were used; a polynaphthalenesulfonate (PNS), a melamine resin (PMS) and a polycarboxylate (PC). They have been incorporated into various amount in a standardized mortar based on limestone cement. The aim of this study was to evaluate the rheological, mechanical and Calorimeters properties of this mortar. This will select the most compatible product and more able to be used depending on the climate of the country and the cement used. The PNS is incompatible with this type of cement registering a decrease of strength but the PMS and the PC modify the kinetics of hydration with significant heat generation and improved mechanical strength. The measured heat flow is significantly influenced by the type and dosage of superplasticizer especially for low dosage. Hydration heat and compressive strength of the different mixtures can be evaluated by determining their ultimate values and ages to reach these values where the correlation coefficients are very satisfactory.

• 콘크리트학회논문집
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• 제24권1호
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• pp.37-44
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• 2012

최근 건설 시공기술의 발달에 따라 고유동 고강도화된 고성능 콘크리트의 사용이 일반화되고 있는 추세이다. 이러한 고성능 콘크리트는 일반 콘크리트에 비해 혼화재 및 고성능AE감수제의 사용 등을 통해 요구 성능을 확보할 수 있으며, 기존의 경우 고성능 콘크리트의 품질 변동에 미치는 혼화재료의 영향에 대해 다양한 연구 결과는 보고되고 있다. 그러나, 콘크리트의 가장 중요한 원자재인 시멘트가 고유동 콘크리트 품질에 미치는 영향에 대한 연구 보고는 아직은 미흡한 실정이다. 따라서 시멘트 품질과 고유동 콘크리트의 유동 특성의 상관성을 검토하기 위해 국내 시판중인 시멘트 제품들을 대상으로 제품별 품질 특성을 명확히 구명하고, 시멘트 품질 특성이 고유동 콘크리트 제조시 유동 특성에 미치는 영향을 평가하였다. 연구 결과 분말도 및 시멘트의 초기 수화과정에 관여하는 화학조성, 간극상 등은 감수제의 사용량에 영향을 미치며, 특히, 분말도는 제조사별 품질 특성에 상관없이 매우 높은 상관성을 나타내고 있다. 강도발현특성에 있어서는 감수제 사용량의 변화는 초기 재령에 영향을 미치지만 장기재령에서는 거의 영향이 없는 것으로 나타났다.

• 콘크리트학회지
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• 제6권5호
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• pp.83-92
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• 1994

• 레미콘
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• 9호통권29호
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• pp.40-54
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• 1991

• 콘크리트학회지
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• 제13권3호
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• pp.32-37
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• 2001

• 콘크리트학회지
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• 제13권3호
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• pp.69-76
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• 2001

• 콘크리트학회지
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• 제8권2호
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• pp.20-31
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• 1996