Structural Degradation of Tobermorite during Vibratory Milling |
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| Authors: | Kaori Sasaki † Tsuguya Masuda ‡ Hideki Ishida † Takeshi Mitsuda § |
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| Affiliation: | Basic Research Center, INAX Corporation, Tokoname, Aichi, 479, Japan
Construction Research Laboratory, Chichibu-Onoda Cement Corporation, Ohsaku, Sakura, Chiba, 285, Japan
Ceramics Research Laboratory, Nagoya Institute of Technology, Asahigaoka, Tajimi, 507, Japan |
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| Abstract: | Mechanochemistry of hydrothermally prepared Al-free and Al-substituted 1.1 nm tobermorite was studied using 29Si NMR, XRD, and TGA-DTA. Tobermorite has a double-chain structure and Al/Si substitution occurs preferentially at bridging tetrahedra. By using the vibration mill, both tobermorites were observed to decompose as a function of milling time to form amorphous C-S-H-like phases. The decomposition rate was higher for the Al-substituted tobermorite. The decomposition process occurs mainly at the bridge portion of the silicate double chain. In the Al-substituted tobermorite, the breakage seems to occur preferentially at the points where Al has replaced Si. On heating the amorphous C-S-H-like phase, wollastonite is formed. However, no decrease was observed at the wollastonite formation temperature. |
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