• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.301-304
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• 2004

The objective of this study is to evaluate the physical properties of ultra fine-ground cement for grouting materials. This study investigates the compressive strength of cement paste, homogenized gel and solidified soil matrix with ultra fine-ground cement. Also It is estimated the injection properties of ultra fine-ground cement. From the test results, the compressive strength of ultra fine-ground cement is higher than that of portland cement. The injection properties are sufficient to apply silt-sand soil and minute-cracked rock bed. Also the properties of soil stability like water permeability coefficient are enough to be adapted various grouting specification.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 추계 학술논문 발표대회
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• pp.94-95
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• 2016

Calcium Silicate Hydrate (C-S-H), which takes up most of the hydration products of Portland Cement (PC), has the greatest impact on the mechanical behavior and strength development of concrete. The exact mechanism of its deformation, however, has not yet been elucidated. The present study aims to demonstrate the mechanism of nano-deformation behavior of C-S-H in tricalcium silicate paste under compressive loading, unloading and reloading by interpreting atomic pair distribution function (PDF) based on synchrotron X-ray scattering. The strain of the tricalcium silicate paste for a short-range of 0 ~ 20 Å under compressive load exhibited two stages, I) nano-packing of interlayer of C-S-H and II) micro-packing of C-S-H globules, whereas the deformation for a long-range order of 20 ~ 40 Å was similar to that of a calcium hydroxide phase measured by Bragg peak shift. Moreover, the residual strains due to the plastic deformation of C-S-H was clearly observed.

• 대한치과의사협회지
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• 제20권11호통권162호
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• pp.929-932
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• 1982

Calcium Hydoxide는 치수복(pulp capping), 생활치수절단술(vital pulpotomy)등에서 bactericidal effect 때문에 많은 사용을 하고 있으며, 최근에는 무수치(pulpless teeth)와 관련된 치근단병소가 있는 경우, 미완성치근단인 경우, 치근흡수, 횡주치근파절(Transverse root fracture)등의 경우에서도 Ca(OH)₂paste를 사용하여 성공적인 근관치료를 할 수 있다. 근관의 instrumentation 과 irrigation후 근과 dressing 은 약 1주일간 행하고 Ca(OH)₂paste를 건조된 근관내에 넣는다. 이때 치근단(root apex)으로부터 약 3~5mm 되게 저속으로 아주 가볍고 부드러운 압력을 가하여 Ca(OH)₂paste를 cotton pellet로 밀어넣고 Sealing(가봉)한다. 이 Temporary sealing은 1개월이상 견딜수 있도록 Cement 또는 Amalgam filling 함이 좋다. Ca(OH)₂paste의 제법은 normal irrigating agents 와 minimal filing으로 시행한다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.112-113
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• 2019

Recently, supplementary cementitious materials such as blast-furnace slag, fly ash and silica fume have been widely used as substitutes for cementitious materials. In this study, the deformation behavior of compressive loading of C₃S paste with 50% fly ash was analyzed by X-ray scattering data and pair distribution function analysis. The obtained results were compared with 131-day-old pure C₃S paste. The Ca(OH)₂ of the C₃S-FA paste showed almost complete elastic behavior, consistent with the deformation behavior of the r-range of 20 to 40, and the C-S-H phase contributed to the range of PDF r-range of less than 20. In addition, C-S-H of C₃S-FA showed greater deformation resistance than C₃S paste.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2008년도 추계학술논문발표회 논문집
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• pp.195-201
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• 2008

When reinforced concrete is subjected to high temperature as in fire, there is deterioration in its properties of particular importance are loss in compressive strength, cracking and spalling of concrete, destruction of the bond between the cement paste and the aggregates and the gradual deterioration of the hardend cement paste. Assessment of fire-damaged concrete usually starts with visual observation of color change, cracking and spalling of the surface. In this paper, it was reported the trends of research and practical use on the Explosive Spalling Properties of the High-Strength Concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.501-506
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• 2001

An experimental study was carried out to investigate recycling of an oyster shell, which is disposed in open-dumped way at coastal oyster factory area. For this purpose, the chemical component and reaction of oyster shell with cement paste was examined. And, the characteristics of hardened concrete was quantitatively investigated in terms of fineness modulus and blending rate of the crushed oyster shell. Test results show that interaction between oyster shell and cement paste was not occurred and the crushed oyster shell can be used as the fine aggregate of concrete. And it is found that blending of an oyster shell caused not to reduce the 28 day compressive strength of concrete. Elastic modulus of the concrete blended with crushed oyster shells decreases with increases the blending rate which the modulus reduced about 10% when oyster shells is blended up to the 20% of the sand substitution.

• International Journal of Concrete Structures and Materials
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• 제10권sup3호
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• pp.65-74
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• 2016

During concrete pumping, the migration and redistribution of particles occur in a pipe and the lubrication layer that forms between the bulk concrete and the pipe wall is the governing factor determining the flow behavior. In order to identify flow behavior of pumping, in this study, the viscoelastic properties related to the microstructural behavior of a flocculated suspension were examined by using dynamic oscillatory measurements. Cement paste is assumed to be a constituent material of the lubrication layer and ten cases of mixing design are employed by changing the proportions of mineral admixtures. The relationship between the yield stress obtained from the steady shear test and the dynamic modulus resulted from the oscillatory shear measurement was derived and the implications of the correlation are discussed. Moreover, based on the investigation of the viscoelastic properties with oscillatory measurements, the initial behavior of pumped concrete was analyzed systematically.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.188-197
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• 2005

Square patterned jet grouting technique is the soil improvement method that shakes the special end monitor left and right like as tail fin and mixing the soil and cement paste after cutting the soil in square shape by injecting the cement paste from installed two nozzles. The structure shape by jet grouting technique can be constructed in various shapes and sizes like as square, circle, and sector form designed by an engineer. Also, it can be constructed without waste material and reduced a construction time of work economically. In this study, the applicability of Square Jet Grouting to reduce permeability is estimated by FEM analysis and in-situ test in many cases which are various coefficient of permeability and breadth of grouting structure.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.715-718
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• 2005

The purpose of this paper is to investigate on hydration, setting time and compressive strength properties of cement paste mixed alkali-free accelerator using aluminum sulfate for shotcrete. The experimental focus is to variouse added element with alkali-free accelerator for shotcrete using aluminum sulfate. When diethanolamine was used as a component of alkali-free accelerator, alkali-free accelerator contributed to increasing early hydration, setting time and compressive strength properties of cement paste and mortar.

• International Journal of Concrete Structures and Materials
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• 제3권2호
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• pp.81-90
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• 2009

This paper proposes a semi analytical model to describe the pore structure of concrete by a set of simple equations. The relationship between the porosity and the microstructure of concrete has been considered when constructing the analytical model. The microstructure includes the interface transition zone (ITZ) between aggregates and cement paste. The predicting model of porosity was developed with considering the ITZ for various mixing of mortar and concrete. The proposed model is validated by the rapid experimental programs. Although the proposed model is semi-analytical and relatively simple, this model could be reasonably utilized for the durability design and adapted for predicting the service life of concrete structures.