• 한국세라믹학회지
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• 제49권6호
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• pp.601-607
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• 2012

The alkali-activation reaction of two types of typical kaolin calcined at various lower temperatures was investigated at room temperature and at elevated temperatures. For the assessment of the reactivity, the temperature increase and the setting time of pastes prepared with calcined kaolin and sodium/potassium hydroxide solution were measured. Unlike raw kaolin, calcined kaolin samples prepared at various temperature showed an alkali-activation reaction according to the different aspects of the changes in the mineral phases. The reactivity with alkaline solutions was exceedingly activated in the samples calcined at $600-650^{\circ}C$, but the reactivity gradually decreased as the temperature increased in a higher temperature range, most likely due to the changes in the crystal structure of the dehydrated kaolin. The activation effect of the calcination treatment was achieved at reaction temperatures that exceeded $60^{\circ}C$ and was enhanced as the temperature increased. The reactivity of the calcined kaolin with an alkaline solution was more enhanced with the solution of a higher concentration and with a solution prepared from sodium hydroxide rather than potassium hydroxide.

• KCI Concrete Journal
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• 제13권1호
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• pp.3-9
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• 2001

This research concerns the effect of kaolin as material of cement admixture. which has the advantage of low price and high adaptability. Kaolin, a kind of soil, is well known as a raw material of pottery. which is widely scat-tered on the earth (especially in Korea). This research shows the method and process for activating kaolin to have the properties of a cement admixture through experiment. In the experiments, kaolin is baked in high temperature and then cooled suddenly to be activated. The temperature zone and time span, on which kaolin is activated are examined. The research looks over the effect of the activated kaolin based on several criteria regarding to chemical and physical characteristic of general admixtures. The results of this research are as follows; kaolin start activation at the temperature above 50$0^{\circ}C$ and make ends of activation at the temperature below 95$0^{\circ}C$ and there was little effect by the change of duration. It is concluded that compressive strength can be increased by putting activated kaolin in the concrete and the activated kaolin is good for water resistance and anti-chemical , and that it is effective for protecting the leakage of hazardous article like Cl- and for protecting damage by an organic salt like acid. The activated kaolin of proper temperature and time is effective in compressive strength, salt resistance and acid resistance. The adaptability of activated kaolin as a cement admixture was shown through this research.

• Archives of Pharmacal Research
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• 제10권4호
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• pp.228-231
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• 1987

Studies on the adsorption of four kinds of bacteria, Staphylococcus aureus, Sarcina lutea, Escherichia coli and Serratia marcescens by activated Korean Kaoline have been carried out to innovate utilization as adsosrbent preparations. In connection with particle size and size fraction, the adsorption was examined by colony counting and spectroscopy. Korean kaolin was purified from Hadong white species of preminum grade and three size fractions were derived from passage through BS # 100, #200 and # 325 mesh sieves, respectively. These were activated at $105^{\circ}$or $280^{\circ}$ for three hours and at $550^{\circ}C$ for one hours. The results indicated that the adsorbing power of Korean kaolin was superior for S. aureus and S. lutea, but E. coli and S. marcescens were not adsorbed by clays. The smaller the particle size, the greater was adsorbing power for Gram-positive bacteria. Threre appears to be justification for its investigations as an ingredient in intestinal adsorbent preparations.

• 공업화학
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• 제27권1호
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• pp.56-61
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• 2016

본 연구에서는 천연 광물질 촉매를 사용하여 $CO_2$ 석탄가스화의 반응특성을 조사하였다. Meng Tai지역의 갈탄에 4종류의 천연 광물질(Dolomite, Silica sand, Olivine, Kaolin)을 각각 5 wt%로 물리적으로 혼합한 후 Thermogravimetric Analyzer (TGA)를 이용하여 800, 850, $900^{\circ}C$에서 $CO_2$ 가스화 반응을 수행하였다. 실험 결과를 Volumetric Reaction Model (VRM), Shrinking Core Model (SCM), Modified Volumetric Reaction model (MVRM)을 이용하여 분석하였다. MVRM이 가장 적합하였다. 반응 온도가 올라감에 따라 반응속도상수가 커졌다. 천연 광물질 촉매를 사용할 경우가 촉매를 혼합하지 않은 경우에 비해 반응속도상수는 커지고 활성화 에너지 값이 낮아졌다. Silica sand를 혼합한 시료의 활성화 에너지 값은 114.90 kJ/mol로 가장 낮은 활성화 에너지 값을 보였다. Kaolin을 혼합한 시료의 경우 $850^{\circ}C$와 $900^{\circ}C$에서 각각 가장 높은 반응속도상수를 보여주다가 $800^{\circ}C$에서 낮은 반응속도상수를 나타냈다. 따라서 Kaolin을 혼합한 경우, 반응 온도가 높아질수록 $CO_2$ 가스화에 좋은 효과가 있을 것이다.

• 한국세라믹학회지
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• 제15권1호
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• pp.21-27
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• 1978

Hadong Kaolin (Halloysite) was granulated cylindrically and treated with 1N aqueous sodium hydroxide solution for 6-48 hrs at 60-10$0^{\circ}C$. The crystalling structure of surface of the products was studied by X-ray powder diffraction method. The reaction rate of halloysite to sodium A zeolite showed a gradual decrease from surface to inner layer. At the surface layer, the reaction mechanism was observed as first order consecutive reaction as follows: halloysitelongrightarrowamorphous aluminosilicatelongrightarrowsodium A zeolitelongrightarrowhydroxysodalite By applying the above reaction mechanism, the rate constants and activation energies was measured.

• 시멘트 심포지엄
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• 32호
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• pp.217-221
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• 2005

메타카올린 형태로 하소된 점토의 활용은 포졸란 반응에 따른 모르타르와 콘크리트에 의해서 최근에 중요시되고 있다. 그래서 시멘트콘크리트강도에서 폐콘크리트 슬러지와 메타카올린에 의한 영향에 대하여 연구하였다. 혼합방법은 메타카올린을 포함하는 폐콘크리트 슬러지의 여러 가지 혼합타입으로 구성되어지며 균형을 잡기 위한 최적의 방법으로 준비하였다. 또한 강도의 증진을 평가하기 위해 메타카올린의 배합 비로 비교하였고, 상대적인 압축강도를 측정하였다. 이 실험은 메타카올린과 슬러지가 활성화 물질로 행동하며 슬러지와 메타카올린의 포졸란 특징 때문에 콘크리트 조절에 의해서 압축강도의 증가를 비교 할 수 있었다. 결과적으로 슬러지 시멘트 모르타르는 자연 시멘트 모르타르에 90$\%$정도의 압축강도를 보였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.433-436
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• 2005

The Fly-ash makes an Alumino-silicate gel when it mixes an alkali or a silicate solution. This Alumino-silicate gel is produced to the activation of an alkali silicate. And this act to the binder and makes a combine of particles. This study involved mechanical strengths of an Alumino-silicate Gel based the Fly-ash with an alkali solution. NaOH, KOH were utilized to an alkali solution. The alkali solution concentration was varied from 6 to 12M and the some added also the Meta-kaolin, Waterglass so that it made high the mechanical performance. Based on the experimental result, the compressive strengths increased as the quantity of the Meta-kaolin increased. And a mechanical strengths appeared according to the concentration of an alkali solution so that it was different. XRD, FT-IR have been used to characterize mechanical performance.

• 한국세라믹학회지
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• 제47권3호
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• pp.223-231
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• 2010

The serious issue of tall building is to ensure the fire-resistance of high strength concrete. The fire resistant finishing method is necessarily essential in order to satisfy the fire resistance time of 3 h required by the law. The fire resistant finishing method is installed by applying a fire resistant material as a method of shotcrete or a fire resistant board to high strength concrete surface. This method can reduce the temperature increase of the reinforcement embedded in high strength concrete at high temperature due to the installation thickness control. This study is interested in identifying the effectiveness of inorganic alumino-silicate compounds including the inorganic admixture such as fly ash and meta-kaolin as the fire resistant finishing materials through the analysis of fire resistance and components properties at high temperature. The study results show that the fire resistant finishing material composed of fly ash and meta-kaolin has the thermal stability of the slight decrease of compressive strength at high temperature. These thermal stability is caused by the ceramic binding capacity induced by alkali activation reaction by the reason of the thermal analysis result not showing the decomposition of calcium hydrate. Inorganic compounds composed of fly ash and meta-kaolin is evaluated to be very effective as the fire resistance material for finishing to protect the concrete substrate by the reason of those simplicity in both application and manufacture. The additional study about the adhesion in the interface with concrete substrate is necessary for the purpose of the practical application.

• BMB Reports
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• 제55권4호
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• pp.181-186
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• 2022

Ventriculomegaly induced by the abnormal accumulation of cerebrospinal fluid (CSF) leads to hydrocephalus, which is accompanied by neuroinflammation and mitochondrial oxidative stress. The mitochondrial stress activates mitochondrial unfolded protein response (UPRmt), which is essential for mitochondrial protein homeostasis. However, the association of inflammatory response and UPRmt in the pathogenesis of hydrocephalus is still unclear. To assess their relevance in the pathogenesis of hydrocephalus, we established a kaolin-induced hydrocephalus model in 8-week-old male C57BL/6J mice and evaluated it over time. We found that kaolin-injected mice showed prominent ventricular dilation, motor behavior defects at the 3-day, followed by the activation of microglia and UPRmt in the motor cortex at the 5-day. In addition, PARP-1/NF-κB signaling and apoptotic cell death appeared at the 5-day. Taken together, our findings demonstrate that activation of microglia and UPRmt occurs after hydrocephalic ventricular expansion and behavioral abnormalities which could be lead to apoptotic neuronal cell death, providing a new perspective on the pathogenic mechanism of hydrocephalus.

• 한국세라믹학회지
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• 제18권1호
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• pp.35-40
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• 1981

The kinetics of the dehydration of Ha-dong kaolin was studied isothermally at various temperatures. Dehydration rate was measured by thermogravimetry method in the temperature range of 440~50$0^{\circ}C$ and the particle size range of 170~325mesh. The general equation f($\alpha$)=kt, where $\alpha$ is the fraction reacted in the time and the function f($\alpha$) depends on the reaction mechanism, was applied to this reaction. The function, f($\alpha$) was obtained by application of reduced-time plot and plot of lnln (1-$\alpha$) vs. ln (time), and expressed as (1-$\alpha$) ln (1-$\alpha$)+$\alpha$=kt. The dehydration followed the diffusion-controlled reaction model and gave activation energy of 30Kcal/mole.