• 제목/요약/키워드: ceramic cement

검색결과 531건 처리시간 0.021초

올세라믹 심미 수복재료의 최신 동향과 적합한 시멘트 선택 및 사용 (Recent Trend of Esthetic All-Ceramic Materials and Guidelines for Correct Cementation)

  • 박영준
    • 대한치과의사협회지
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    • 제58권7호
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    • pp.413-434
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    • 2020
  • Recently, there are much improvement in optical and mechanical properties of dental ceramic materials coupled with improved fabrication techniques, which have caused a considerable shift in the preference of the dentists to ceramic restorations. Because the chemical composition and microstructure of all-ceramic materials are different by the type, correct choice of cement type and surface treatment procedure, and cementation strategy is essential for the success of ceramic restorations with adequate retention and decreased incidence of complications. This manuscript reviews on the most often prescribed and some newly developed ceramic materials, and the selection criteria and usage guidelines of cement materials that are used in conjunction with various ceramic materials. This manuscript emphasizes that continuous updating the information of newly developed ceramic and cement materials and application techniques by the dentists and dental staffs are demanding in response to the constantly improving ceramic and cement materials and corresponding application protocol changes.

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재생미분말의 흡착특성과 유동특성 (Adsorption and Fluidity Properties of Recycled Cement Powder)

  • 이종규;추용식;정석조
    • 한국세라믹학회지
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    • 제43권12호
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    • pp.846-851
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    • 2006
  • This paper discuss the adsorption and fluidity properties of recycled cement powder with different hydration hysteresis and particle size. Reactivity of hydrated fine powder was negligible low. Therefore, the adsorption and fluidity properties with super-plasticizer for hydrated recycled cement powder was very important for using additive material. Adsorption amount of super-plasticizer was increased by the finer hydrated recycled cement powder addition. And the fluidity of hydrated recycled cement powder was very poor than un-hydrated cement powder. To Improve the fluidity of hydrated recycled cement powder, PC super-plasticizer is the more effective than NS super-plasticizer.

Regression Analysis on the Effect of Compressive Grinding of Cement Raw Materials and Clinker Granule

  • Kim, Jong-Cheol;Auh, Keun-Ho
    • The Korean Journal of Ceramics
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    • 제6권2호
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    • pp.96-99
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    • 2000
  • Particle size of the cement raw materials is important not only in clinker burning but also in cement productivity. Model experiment was designed to investigate the effect of compressive grinding on cement raw materials and clinker granule. Compressive grinding was more efficient in reducing hard materials like quartz. Regression model was constructed to explain the effect of compressive grinding on the size reduction of cement raw materials and clinker.

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Hydration Mechanism of Alkali Activated Slag Cement

  • Jong Cheol Kim;Keun Ho Auh;Sung Yun Hong
    • The Korean Journal of Ceramics
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    • 제5권1호
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    • pp.35-39
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    • 1999
  • For many years, alkali activated blast furnace slag cement containing no ordinary portland cement has received much attention in the view of energy saving and its many excellent properties. We examined the structural change of slag glass which was activated by alkali metal compounds using IR spectroscopy. The properties of hydrated products and unhydrated slag grains was characterized by XRD and micro-conduction calorimeter. Ion concentration change in the liquid during the hydration of blast furnace slag was also studied to investigated the hydration mechanism.

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Physical Properties of Cement System Insulation Using Blast Furnace Slag

  • Seo, Sung Kwan;Park, Jae Wan;Cho, Hyeong Kyu;Chu, Yong Sik
    • 한국세라믹학회지
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    • 제55권1호
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    • pp.61-66
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    • 2018
  • In this study, fabrication method of inorganic insulation were studied to reduce $CO_2$ from buildings. Main materials for inorganic insulation were used cement, blast furnace slag and aluminum powder as foaming agent. Mixing ratio of cement and slag was controlled and physical properties of inorganic insulation were analyzed. When inorganic insulation was fabricated using cement and slag, expanded slurries were not sunken and hardened normally. Pore size was 0.5 - 2 mm; mean pore size was about 1mm in inorganic insulation. Compressive strength of inorganic insulation increased with curing time and increased slightly with cement fineness. However, specific gravity decreased slightly with curing time; this phenomenon was caused by evaporation of adsorptive water. When inorganic insulation was dried at $60^{\circ}C$, compressive strength was higher than that of undried insulation. The highest compressive strength was found with a mixture of cement (50%) and slag (30%) in inorganic insulation. Compressive strength was 0.32 MPa, thermal conductivity was 0.043 W/mK and specific gravity was $0.12g/cm^3$.

The characteristics of mineral hydrate insulation material using activated cement prepared from pilot plant activation system

  • Seo, Sung Kwan;Chu, Yong Sik;Kim, Tae Yeon;Kim, Yoo
    • Journal of Ceramic Processing Research
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    • 제19권5호
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    • pp.428-433
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    • 2018
  • In this study, using the pilot plant activation system, the activated cement has been manufactured and then applied to the manufacturing process of mineral hydrate insulating material. The fineness of the activated cement is controlled at $5,000cm^2/g$ and $7,500cm^2/g$ and the features of mineral hydrate insulating material, using OPC and the activated cement for each degree of fineness, has been analyzed. As the result of analyzing the crystal habit of the manufactured mineral hydrate insulting material, it is analyzed that the main crystal phase of specimen is tobermorite and some quartz peak has been detected. As the degree of fineness of the activated cement increases, the height of bubble of slurry increases as well, whereas the tendency for the density character to decrease has been detected. Along with it, as the density character decreases, the compression strength has decreases, whereas the tendency for the thermal characteristic to increases has been detected. The main features of mineral hydrate insulating material, using the activated cement with the fineness of $7,500cm^2/g$, the compression strength of 0.36 MPa, and the thermal conductivity of $0.044W/m{\cdot}K$, presents the excellent features as insulation.

산업부산물을 이용하여 제조된 시멘트 클링커의 수용성 6가 크롬 용출 특성 (Leaching Properties of Water-Soluble Hexavalent Chromium in Manufacturing Cement Clinker Using Industrial By-Products)

  • 이정희;추용식;송훈;이종규
    • 한국재료학회지
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    • 제20권4호
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    • pp.181-186
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    • 2010
  • Since it was developed by Joseph Aspdin, cement has been a common construction materials up to the present time. However, there are trace constituents in cement clinker. One of the trace constituents included in cement clinker, chromium, has become prominent and highly noticed lately as a social issue both inside and outside of this country because it affects the human body negatively. The aim of the present study was to investigate the concentration of water-soluble hexavalent chromium in cement clinker by using industrial by-products. For that reason, raw materials were prepared to add different $SiO_2$, $Al_2O_3$, and $Fe_2O_3$ sources. After the raw materials such as the limestone, the sand and the clay, iron ore was pulverized and mixed, and the raw meal was burnt at about $1450^{\circ}C$ in a furnace with an oxidizing atmosphere. The part in the raw materials of the clinker was substituted with slag, sludge, etc. and this was used to manufacturing cement clinker. To investigate the water-soluble hexavalent chromium content in clinker, raw meal was prepared by changing the modulus, the type, and the content of clinker materials and tested concentrations of hexavalent chromium in the clinkers. To determine $Cr^{+6}$ formation of the clinker, tests were done with raw meals adding chromium by using different industrial by-products. Consequently because the chromium was to be included in the raw materials of the clinker, production of Portland cement clinker was included with the chromium. Also, the chromium was converted into hexavalent chromium in the burning process.

The Influence of FGD Gypsum Fabricated from Limestone Sludge on Cement Properties

  • Seo, Sung Kwan;Chu, Yong Sik;Shim, Kwang Bo;Lee, Jong Kyu;Song, Hun
    • 한국세라믹학회지
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    • 제53권6호
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    • pp.676-681
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    • 2016
  • For the purpose of reducing the amount of limestone, which is used as a desulfurization agent to absorbing $SO_X$ gas in thermal power plants, and to recycle limestone sludge generated from a steel mill, limestone sludge was utilized as a desulfurization agent. In this study, cement, made of flue gas desulfurization (FGD) gypsum obtained in a desulfurization process using limestone sludge, was manufactured then, experiments were conducted to identify the physical properties of the paste and mortar using the cement. The results of the crystal phase and microstructure analyses showed that the hydration product of the manufactured cement was similar to that of ordinary Portland cement. No significant decline of workability or compressive strength was observed for any of the specimens. From the results of the experiment, it was determined that FGD gypsum manufactured from limestone sludge did not influence the physical properties of the cement also, quality change did not occur with the use of limestone sludge in the flue gas desulfurization process.

Mechanochemical Processing(MP)에 의한 Cement-fly Ash 계 Mortar의 제조 (Fabrication of Cement-fly Ash Mortar by Using Mechanochemical Processing(MP))

  • 이형직;구자훈;유인상;송두규;정해경;권혁병;윤상옥;이형복;이홍림
    • 한국세라믹학회지
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    • 제39권2호
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    • pp.126-134
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    • 2002
  • Mechanochemical Processing(MP)을 거친 Cement(MPC) 또는 Fly Ash(MPFA)를 사용하여 fly ash 다량 혼화 고강도 mortar의 제조를 위한 연구를 수행하였다. 단순 ball milling processing를 거친 cement(Ball-mill Processed Cement, BPC)와 채취 그대로의 처리하지 않은 fly ash(As Received Fly Ash, ARFA) 혼화시의 공시체와 비교하여 동일한 fly ash의 혼화량(10, 20, 30 wt%), 동일한 재령(7일 및 28일)의 압축강도 및 미세구조의 관점에서 고찰하였다. MPC와 ARFA 및 BPC와 MPFA를 사용한 mortar 공시체가 BPC와 ARFA를 사용한 것보다 각각 5-11% 및 10-20% 상승한 압축강도 값을 나타내었다. 더욱이 MPC와 MPFA의 동시 혼화 mortar 공시체의 압축강도가 fly ash 혼화량 20 wt% 공시체에서 강도 상승률 24%를 나타내었는데 이 값은 MPC 사용에 의한 강도 향상 비율(8%)과 MPFA 혼화에 의한 강도 향상 비율(12%)의 합을 상회하는 synergy 효과를 나다내는 강도 향상율을 나타냈다. 상기의 강도 증진은 MP에 있어서 fly ash와 cement 입자가 혼합되면서 기계적 에너지가 공급되므로 각 입자의 서로에 대한 친화성이 증대되며, 이로 인하여 수화물 생성시 cement와 fly ash 입자간의 결합력이 더욱 증가하게 되어 압축강도가 증가하는 것으로 고려된다.