When 12CaO⋅7Al₂O₃ was dispersed in aqueous solution at 20°C, the quantities of effluent calcium and aluminium in various durations indicated the super saturation phenomena. On the other hand, when 12CaO⋅7Al₂O₃ was dispersed in solution of Ca(OH)₂, it was suggested generally that these quantities were greatly decreased because of the formation of 2CaO⋅Al₂O₃⋅8H₂O.
However, the quantity of effluent calcium was increased also in solution of Ca(OH)₂. The processes are seemed different from those found in the previous reports. 2CaO⋅Al₂O₃⋅8H₂O was detected at the time of elimination of super saturation phenomenon.
Furthermore, the authors confirmed by the electro-conductivity as well as the effluent quantities. The change of electro-conductivity vs. the hydration time was closely connected with the effluent quantities. Namely, it is apparent from the results of experiments that the maximum phenomenon on the electro-conductivity curves have existed also in solution of Ca(OH)₂.
The hydration processes of 12CaO⋅7Al₂O₃ in solution of Ca(OH)₂ were observed by scanning electron microscopic photographs. Accordingly, it was elucidated the products of card house states consisted of 4CaO⋅Al₂O₃⋅13H₂O and 2CaO⋅Al₂O₃⋅8H₂O in the early hydration processes. Therefore, the flash setting of 12CaO⋅7Al₂O₃-Ca(OH)₂ system is produced by the formation of card house states.

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Stresses in the glaze and the crystal content of the body of vitreous chinaware biscuit-fired under various conditions were measured. When the body was biscuit-fired in a shuttle kiln at different temperatures from SK 9 (1280°C) to SK 121/2 (1365°C) with a 30 to 40h firing cycle, the amount of quartz dissolved increased with an increase in the firing temperature, but the amount of cristobalite deposited was not large enough to keep a suitable total crystal content [I_Q(100)+1/6⋅I_Cr(101)], because of the short cooling time. The resultant decrease in the total crystal content gave rise to a decrease in the compressive stress in the glaze with an increase in the firing temperature. This shows that over-firing in a short firing cycle is unfavorable to crazing resistance. On the other hand in the firing to SK 12 (1350°C) in a large tunnel kiln for mass production, the firing cycle of which was either 42 or 126h, a large amount of cristobalite was formed in the bodies and the total crystal content came to the value which was favorable for crazing resistance.
The favorable tendency was observed in the bodies fired with a 126h cycle, in which a larger amount of cristobalite was formed than in those fired with a 42h cycle.
In the tunnel kiln the effect of the heat is apt to differ with regard to the setting place. The best position proved to be in the upper setting place and in the center of the lower setting place. At the upper setting position, the cristobalite formation was sufficient to keep a suitable total crystal content because of the slow cooling rate, even when the bodies were subjected to hard firing and quartz was much dissolved. In the center of the lower setting place, a large amount of quartz remained undissolved and kept the total crystal content favorable for crazing resistance. Concerning the bodies placed at the lower setting positions other than in the center, if they sometimes happened to be over-fired, the quartz content became less due to dissolution, but the formation of cristobalite, however, was less because of the rapid cooling rate, So, the resulting decrease in the total crystal consent gave rise to poor crazing resistance. It is concluded that vitreous chinaware biscuit-fired in the upper setting place of a car are considerably safer from crazing.

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Utilization of burnt residue was studied as a preliminary research on the resource recovery project from urban residues. Tested materials of burnt residues in this study were supplied from incineration plants in large cities. The residues were classified into inorganic materials and burnt ash passing through a 5mm sieve.
At the laboratory test it was found that mixture of 45% inorganic materials, 10% ash and 45% red mud being pelletized in a size of 10mm, was fired at 900°C to form a light-weight aggregate. Extended studies for commercial production were carried out with a extruding pelletizer and a 7m rotary kiln. As a result, the light-weight aggregate of 1.24 in apparent specific gravity and 14.86% in water absorption fraction could be produced. Concrete test results of light-weight aggregate met the JIS A 5002 (Light-weight Concrete for Structure).
Floor and wall tiles were trially manufactured from the inorganic materials mixed with equilibrated amount of Gairome clay. The tiles were formed by a dry pressing method at 250-300kg/cm² and burnt at 1060°C. The quality satisfied the JIS A 5209 (Ceramic Tiles).

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