2001 Fiscal Year Final Research Report Summary
Synthesis ofHeatResistance Wall Material fconi Sliirasu in the Kagoshima Prefecture
| Project/Area Number |
12650825
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
無機工業化学
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| Research Institution | Kagoshima University |
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Principal Investigator |
UEMURA Hisako Kagoshima University, Faculty of Engineering, Research Associate, 工学部, 助手 (20041535)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Shirasu / Tobermorite / Hydrothermal reaction / alkali / トバモライト |
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| Research Abstract |
The Shirasu, a volcanic ash is distributed widely in southern Kyushu, Japan. The SiO_2/Al_2O_3 mole ratio in shirasu (SiO_2 : 72.20 %, Al_2O_3 : 12.41, K_2O : 3.44, CaO : 1.29) and 11-tobermorite(10CaO・Al_2O_3・10SiOa・10H_2O) with heat-resistance are almost equal. 11-Tobermorite was synthesized from shirasu by the two methods.
1. The first method with alkali (KOH).
2. The Second method by alkali-free
By the first method : 11-Tobermorite was synthesized from shirasu by two steps hydrothermal reaction in an autoclave. At the first step, the materials were mixed at suitable amount (CaO/SiO_2=1.0, K_2O/SiO_2=0.32), and is pretreated in the autoclave at 60℃ for 5 hours to prereact. At the next step, 11-tobermorite was obtained by the way of increasing temperature to 150℃. In the first step, Si-O in shirasu is thought to be decomposed with alkali, and Ca adsorbed, and then 11-tobermorite nucleation place. But under condition of above 60℃ for 5 hours, alkali dissolved Ca and 11-tobermorite nuclea. In the next step, 11-tobermorite, crystal seed grows immediately.
But the second method of alkali-free the materials are only shirasu, Ca(OH)_2, and water. The langer reaction time was necessary in compared with method by alkali, but the pretreatment was not necessary.
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