• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.533-536
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• 2006

PC-type copolymers were synthesized using MPEG(Polyethylene glycol methyl ether methacrylate, Mn=2080) to different mole ratios of mono-carboxylic acid(AA : Acylic acid). The mole ratios of AA were 2, 3, 4. To investigate effects of PC-type co-polymers on the hydration of cement, experiments involving FT-IR, XRD, SEM have been analysed with cement paste specimens to 1, 3, 28 day. The hydration reaction rate of cement paste was slightly delayed at 1 day, due to increase in molar ratio of [AA] / [MPEG], it was recovered in the days after.

• 한국세라믹학회지
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• 제27권3호
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• pp.437-443
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• 1990

The resistivity of cement paste and mortar for freezing and thawing was investigated for densifying the structure of cement paste and mortor, slag, diatomaceous earth and fly ash as blending materials and superplasticizer were used, and air entraining agent was added to absorb the volume expansion by freezing and thawing reaction. And then the specimens were subjected to freeze-thaw in water. When both of air entraining agent and superplasticizer as additives were mixed to specimens, their freeze-thaw resistance was enhanced by the air entraining effect and the water reduction effect. When 4% of slag were added to cement, freeze-thaw resistance was especially excellent. In addition, it was found that the specimens with blending materials were more influenced by curing periods than those without admixture. It is assumed that the curing periods contribute to exibit the potential hydraulicity and pozzolanic reactivity of blending materials and to densify their texture.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.13-14
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• 2022

This study investigated the effect of fly ash content on the isothermal hydration heat of cement pastes. Two different pastes with fly ash content were studied to cure at 35℃. The hydration heat flow deceleration stage of slurry was simulated and compared by Jander Equation and Ginstling-Brounshtein Equation. The results show that Jander Equation and Ginstling-Brounshtein Equation have certain defects in the modeling of the deceleration stage of the heat flow of cement fly ash paste, and the fitted curve can not describe the deceleration stage well.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.95-96
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• 2022

Carbon nanotubes has a positive effect on the mechanical properties, functionality, and durability of cement-based materials. In this study, carbon nanotube solutions mixed with two different types of superplasticizers were dispersed by high-pressure homogenizer, and used for preparation of cement paste. The 7and 28day compressive strength were evaluated.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.151-152
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• 2020

When concrete is exposed to fire, the thermal decomposition of hydrates of Portland cement paste results in critical damage to the concrete structure of a building. Recently, nanosilica arose as the effective nano-additive which can enhance the thermal resistance of the cementitious materials. However, the mechanism of the enhancement was not elucidated specifically. In this study, we investigated the properties of calcium silicate hydrates(C-S-H)of the nanosilica incorporated cement paste after heating to different heating temperatures (200℃, 500℃, and 800℃) by 29Si nuclear magnetic resonance. The results showed that the polymerization of C-S-H of nanosilica incorporated samples was larger than ordinary cement paste after heating to 200℃, and C-S-H formed during heating process to 500℃ due to the pozzolanic reaction during heating process.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.129-130
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• 2021

In order to solve the problem of low early-age compressive strength of high volume fly ash concrete. This paper studies the effect of 2% sodium sulfate (Na₂SO₄) as a chemical activator on the paste with 40% fly ash content and a water-binder ratio of 0.30. The results indicate that the addition of Na₂SO₄ can effectively improve the early-age compressive strength of the fly ash-cement system, and the strength improvement rate on the first day reached nearly 70%. In addition, calorimetric analysis reveals that the incorporation of Na₂SO₄ promotes the early hydration of cement and fly ash, increases the cumulative hydration heat and delays the heat peak of the aluminum phase.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 가을 학술논문 발표대회
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• pp.174-175
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• 2021

Currently, the construction structures become larger and more high-performance in modern society, demands for ultra-high strength and light weight construction materials are increasing rapidly. Therefore, this study aims to confirm the applicability of nanomixed cement supplemented with physical and mechanical properties using nanomaterials.Changes in compressive strength and properties were analyzed according to the ratio of cement paste and dispersant (PCE) made by ultrasonication of carbon nanotubes (CNT)

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.305-306
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• 2023

Recently, as the radioactive waste disposal facility becomes scarce, the importance of efficient disposal of waste from nuclear power plants is increasing. This study was conducted to utilize radioactive waste concrete powder as solidifying agent for radioactive waste treatment. Paste with an age of more than one year was used with a disk mill to have a particle size of 150㎛ or less, and treated at temperatures of 500℃, 600℃ and 700℃ for 2 hours. In order to simulate the radioactive cement powder, aqueous solutions of Di-water, CsCl 1M, SrCl₂ 1M and CoCl₂ 1M were used as blending water at W/C 0.7 and to improve fluidity, polycarboxylate type superplasticizer was used at 0.4 wt.% based on the weight of recycled cement paste powder. Characterisation was carried out using vicat method, strength and density.

• Computers and Concrete
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• 제22권2호
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• pp.153-159
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• 2018

Accelerators are used to speed up the construction by accelerating the setting time which helps in early removal of formwork thus leading to faster construction rate. Admixtures are used in mortar and concrete during or after mixing to improve certain properties of material which cannot be achieved in conventional cement mortar and concrete. The various industrial by products make nuisance and are hazardous to ecosystem as well. These wastes can be used in the construction industries to reduce the consumption of cement/aggregates, cost; and save the energy and environment by utilising waste and eliminate their disposal problem as well. The effect of calcium nitrate and triethanolamine (TEA) as accelerators and marble powder (MP) as waste material on the various properties of cement paste and mortar has been studied in the present work. The replacement ratio of MP was 0-10% @ 2.5% by weight of cement. The addition of calcium nitrate was 0% and 1%; and variation of addition of TEA was 0-0.1@ 0.025% and 0.1-1.0@ 0.1% by weight of cement. On the basis of setting time, some mix proportions were selected and further investigated. Setting time and soundness of cement paste; compressive strength and microstructure of mortar mix of selected mix proportions were studied experimentally at 3, 7 and 28 days aging. Results showed that use of MP, calcium nitrate, TEA and their combination reduced setting time of cement paste for all the mixes. Addition of calcium nitrate increased the compressive strength at all curing ages while MP and TEA decreased the compressive strength. The mechanism of additives was discussed through scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis of the specimens.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.741-744
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• 2008

일정 수준의 콘크리트 품질 수준을 유지하면서 시멘트 사용량을 줄이는 방법으로는 첫째, 다양한 입형과 입도의 골재 사용, 둘째, 사용되는 시멘트의 일부를 광물질 혼화재 및 광물질 채움재로 대체하는 방법등이 있다. 또한 페이스트의 구성성분이 합리적인 범위라면, 일정 수준의 품질을 유지하기 위하여 필요한 최소 페이스트 체적은 페이스트 구성성분과는 무관할 것으로 생각된다. 따라서 본 연구에서는 일정 수준의 워커빌리티를 유지하기 위하여 콘크리트에서 필요로 하는 최소 페이스트 체적을 결정하고자 하였다. 이를 위하여 입도가 다른 3종류의 골재에 대하여 페이스트의 체적을 변화시키면서, 고성능감수제를 사용하여 모르타르의 플로우값 130을 유지하는데 필요한 최소 페이스트체적에 대하여 연구하였다.