• Title/Summary/Keyword: tobermorite

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Preparation of 1.1-nm Tobermorite from Starting Zeolite Mineral (Zeolite광물을 출발물질로 한 1.1-nm Tobermorite의 제조)

  • Yim, Going
    • Journal of the Korean Ceramic Society
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    • v.36 no.3
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    • pp.274-283
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    • 1999
  • 1.1-nm tobermorite의 수열합성에 SiO2원으로 zeolite광물을 출발물질로하여 소석회와 Ca(Si+Al)의 몰비 0.8~1.0로 150$^{\circ}$~23$0^{\circ}C$,8~48시간 동ㅇㄴ 포화증기압하에서 수열반응을 시킨 결과, 반응초기단계에서 tobermorite가 생성되었고, 고결정성 1.1-nm tobermorite의 최적합성조건은 0.8몰, 23$0^{\circ}C$, 48시간이었다. 출발물질중 Al의 존재로 tobermorite는 Ca/(Si+Al)몰비 0.8이 1.0보다 결정화가 급속히 이루어지고 있으나 Al를 함유치 않은 석영의 경우에는 Ca/Si 몰비 1.0이 0.8에서 보다 결정화가 빠르게 진행되었다 1.1-nm tobermorite는 $700^{\circ}C$에서 일주일간 가열처리하여도 저면간격이 변화하지 않는 열적거동이 이상형임을 보여주었다. 특히 출발물질중 Al의 존재는 1.1-nm tobermorite의 결정화와 안정화를 촉진시켜주며 Al이온이 tobermorite구조중의 Si이온과 동형치환을 한다.

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Influence of Alumina on Hydrothermal Synthesis of 11Å Tobermorite (알루미나가 11Å Tobermorite의 수열합성에 미치는 영향)

  • Yim Going;Yim Chai Suk
    • Korean Journal of Materials Research
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    • v.15 no.2
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    • pp.97-105
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    • 2005
  • [ $11\AA$ ] tobermorite$(5CaO{\cdot}6SiO_2{\cdot}5H_2O)$ is synthesized from the mixtures of calcium hydroride and quartz using alumina in a molar ratio $Ca(OH)_2/SiO_2$ of 0.8 at $180^{\circ}C$ for 8 and 24 hrs under saturated steam pressure. The influence of alumina on the formation of $11\AA$ tobermorite was investigated by X-ray diffraction, differential thermal analysis and infrared spectroscopy. $11\AA$ tobermorite containing increasingly larger amounts of aluminum showed a shift of the basal spacing from 11.3 to $11.6\AA$. In general, there was a direct linear relation between the basal spacing and added content of alumina. The differential thermal analysis curves showed that $11\AA$ tobermorite with increasing alumina contents exhibited the exothermic peak at high temperature, namely $11\AA$ tobermorite containing aluminum gave a sharp exothermic peak at temperature around $850\~860^{\circ}C$ in the case of $S_3\~S_5$. The absorption band at $1607\~1620cm^{-1}$ is attributed to the bending vibration of water, and the position of the main O-H stretching and Si-O lattice vibration of $11\AA$ tobermorite at 3500 and $965cm^{-1}$ respectively is not altered. Consequently the existence of alumina accelerates the crystallization of $11\AA$ tobermorite, and that the aluminum ion appears to substitute for the silicon ion in $11\AA$ tobermorite structure. Al-containing tobermorite is distinguished from Al-free tobermorite.

The Thermal Transformation of Tobermorite-Studies on The Thermal Transformation of Calcium Silicate Hydrates(II)- (Tobermorite의 가열변화 -규산칼슘 수화물의 가열성상에 관한 연구(II)-)

  • 이종근;최상흘;한상목
    • Journal of the Korean Ceramic Society
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    • v.11 no.4
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    • pp.25-30
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    • 1974
  • The mixture of quartz powder and slaked lime with plenty water was oscillated in an autoclave and treated hydrothermally under the pressure of 10 kg/$\textrm{cm}^2$ for 8 hours. The main mineral synthesized was confirmed 11$\AA$ tobermorite by the method of X-ray diffraction and selected area electron diffraction. Tobermorite was heat-treated at 40$0^{\circ}C$, 80$0^{\circ}C$ and 100$0^{\circ}C$ for investigation of transformation of morphology and structure. Electron micrographs showed the thin platy structure of synthetic tobermorite with a little of crumpled foil or fibrous semi-crystalline calcium silicate hydrates. No difference in structure was appeared under the temperature of 80$0^{\circ}C$ but tobermorite converted gradually into wollastonite at 800$^{\circ}$~85$0^{\circ}C$. On heating, moulded material from tobermorite hardly shrinks under 80$0^{\circ}C$.

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A Study on the Hydrothermal Synthesis of Tobermorite in the System of CaO-SiO2-H2O and Cement Sludge-SiO2-H2O (생석회-규사-수계 및 시멘트 슬러지-규사-수계에서 Tobermorite의 수열합성에 관한 연구)

  • Rho, Jae-Seong;Hong, Seong-Su;Cho, Heon-Young;Choi, Sang-Won
    • Applied Chemistry for Engineering
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    • v.4 no.2
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    • pp.291-299
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    • 1993
  • Hydrothermal synthesis of 1.13nm tobermorite was performed to obtain the mixing ratio of raw materials, the optimum reaction time and the effect of aluminum in two systems, $CaO-SiO_2-H_2O$ and cement sludge-$SiO_2-H_2O$. 1.13nm tobermorite($5CaO{\cdot}6SiO_2{\cdot}5H_2O:C_5S_6H_5$) was synthesized excellently from $CaO-SiO_2-H_2O$ system on each mole ratio (0.4, 0.8) of $CaO/SiO_2$ at $180^{\circ}C$. But a tobermorite crystals had a sign of crystal conversion after 6 hours of reaction times in the case of $CaO/SiO_2=0.4$ and 4 hours of reaction time in the case of $CaO/SiO_2=0.8$. However, a tobermorite synthesized from cement sludge wastes did not show the crystal conversion on each mole ratio(0.4, 0.8) of $CaO/SiO_2$ within 10 hours of reaction times. It is considered that aluminum ions dissolved from cement sludge wastes retarded the recrystallization of tobermorite. This role of aluminum ion was confirmed in $CaO-SiO_2-H_2O+Al$ powder system. According as added amount of Al powder was increased from 0.8% to 3.0%, the crystal had a highly flatter and larger shape. Recrvstallization was not detected within the same reaction times when aluminum was added.

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The Solubility of Calcium Silicate Hydrates (규산석탄수화물의 용해도에 관한 연구)

  • 이경희
    • Journal of the Korean Ceramic Society
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    • v.15 no.1
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    • pp.16-20
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    • 1978
  • The solubility of tobermorite was measured, and it was compaired with the resultswhich calculated by thermodynamic data. As the result, 1) The type of silisic acid species in liquid phase were the both type of $H_3SiO_4$-, $H_4SiO_4$. 2) The solubility product of tobermorite represented the maximum value at 18$0^{\circ}C$.

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Strength Variations of Light Weight Foamed Concrete According to the Autoclaving Time (오토클레이브 양생시간에 따른 경량기포콘크리트의 강도 변화에 관한 실험적 연구)

  • Kang Cheol;Kang Gi Woong;Kang Eun Gu;Noh Jea Myoung;Kwon Gi Ju;Kim Jin Man
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2005.05a
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    • pp.57-60
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    • 2005
  • This is the experimental study on the strength development of the light weight concrete block according to the autoclaving time. The calcareous source used the cement, siliceous material used the bottom ash ground to fine particle, and the PP fiber used to increase toughness. The results of this experiment are as follows. According to the increase of autoclaving time and the fiber content, compressive and flexural strengths are increased. Despite of the changes of the autoclaving time, tobermorite was produced on each of the specimens. However, the phase of tobermorite was changed in accordance with the changes of autoclaving time.

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The Microstructure and Mechanical Properties of Fiber Reinforced Calcium Silicate Hydrates (섬유보강 규산칼슘수화물 경화체의 미세조직과 기계적 특성)

  • 엄태선;최상흘
    • Journal of the Korean Ceramic Society
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    • v.34 no.5
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    • pp.491-499
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    • 1997
  • High flexible lightweight composites containing tobermorite as a main mineral is produced using various amorphous silicates, lime, cement and fibers. Here, Mechanical properties of the composites were studied by observing microstructures of hydrates and fibers. Amorphous silicates having better hydraulicity retarded the crystallization of tobermorite due to better formation of C-S-H gel in water bath curing, but, difficult conversion from C-S-H gel to tobermorite in hydrothermal reaction. In the low molar ratio of CaO/SiO2 (0.67), faster crystalization was observed dued to more impurities such as Al2O3 alkali, resulting in improving mechanical properties due to small crystal size and many contact points. It was identified that a lot of calcium silicate hydates formed at surface of pulps increase bonding strength and the crack-resistance of matrix in the composites, but decrease hardness and compressive strength. The choice of amorpous silicates having better hydraulicity, low CaO/SiO2 adding each fibers bellow about 5% in the raw mixs and lower molding pressure should be needed at improve mechanical properties of composites.

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Effect of Gypsum and Cement on Hydrothermal Reaction in Fly Ash-Lime System (플라이 애쉬-석회계 수열반응에 있어서 석고 및 시멘트의 영향)

  • 안민선;박태균;황인수;김병익
    • Journal of the Korean Ceramic Society
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    • v.35 no.10
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    • pp.1030-1039
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    • 1998
  • In fly ash-lime system the effects of reaction condition amounts of gypsum and cement and CaO/SiO2 ratio on the hydrates by hydrothermal reaction were investigated. The tobermorite phases were not observed in hy-drothermal reaction of fly ash lime because of the hydrate rate was very slow. The compressive strength and the hydration rate increased with increasing the amount of gypusm and cement and the optimum amounts of gypsumo and cement were 5wt and 20wt% respectively. The specimen which CaO/SiO2 ratio is 0.85 was shown the maximum compressive strength and the tobermorite phase within reaction time 2 hours.

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Hydrothermal Reactivity of Various Classified Fly Ashes by Electrostatic Precipitator (전기집진장치로부터 단별채취한 플라이 애쉬의 수열반응성)

  • ;Estuo Sakai;Masaki Daimon
    • Journal of the Korean Ceramic Society
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    • v.37 no.8
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    • pp.811-816
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    • 2000
  • This paper discussed hydrothermal reactivity of Ca(OH)2 and classified bituminous fly ashes which were collected at an electrostatic precipitator in coal fired power plant at 181$^{\circ}C$. The major products of hydrothermal reaction were tobermorite and hydrogrossularite because bituminous fly ashes contained Al2O3 content greater than 20 wt%. As increasing amount of Al2O3 content greater than 20 wt%. As increasing amount of Al2O3 in glass phases, formation of hydrogrossularite increased. Formation rate of crystalline tobermorite increased with content of finer particles, higher glass content and more Al2O3 in glass phases. There was a positive correlation between residue on 45${\mu}{\textrm}{m}$ sieve and hydrothermal reactivity of fly ash up to 3 hours. The hydrothermal reactivity of fly ash at 181$^{\circ}C$ for 12 hours was more affected by fineness than by glass content of fly ash.

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Colors and Crystals of ALC Surface with Green Body's Staying Time (성형체의 대기시간에 따른 ALC 표면 색상과 결정특성)

  • Chu, Yong Sik;Seo, Sung Kwan;Park, Soo Hyun;Song, Hun;Lee, Jong Kyu
    • Journal of the Korean Ceramic Society
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    • v.49 no.6
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    • pp.535-541
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    • 2012
  • ALC was fabricated using cement, lime, quartzite and a foaming agent via a hydrothermal reaction. ALC has various hydrothermal reaction products and many pores. The properties and colors of ALC surfaces were changed by various factors during ALC fabrication process. This study tested various staying times to analyze these phenomena. It was found that the staying time of green body influenced the properties of hydrothermal products and color of ALC surface. The longer staying time of green body, the lower tobermorite content and cumulative loss weight. An increase in holding time changed color and decreased whiteness of ALC surface. The relationship between whiteness and cumulative loss weight was very high (Coefficient, r = 0.95). It was surmised that tobermorite content was an important factor for enhancement of whiteness However, ettringite and quartzite did not contribute to whiteness.