The authors, in continuing their previous report (This Journal,
62 [696] 403-406 (1954)), report in the present paper the results of further studies on the reaction between lime and various siliceous pozzolanic materials as Portland cement admixture. Three siliceous admixtures, i.e., (1) Beppu-hakudo from Oita Pref., (2) Matsuyama-hakudo from Saitama Pref., and (3) Oya-ishi from Tochigi Pref., are most famous in Japan, and were collected and analysed by the total analysis and the special soluble analysis. Nextly, these samples were analysed to confirm the amounts of soluble silica, alumina and Fe
2O
3 by heating with dilute HCl (
d=1.12) solution at 20°C or 50°C- the so-called “Florentin” method. The amount of free lime in the hardened test piece of lime (50 parts) with one of the above siliceous admixtures (50 parts), was determined by the tribrophenol method or the glycerine-alcohol solution method (ASTM). And then, the hydrated reaction products between lime and siliceous admixture were calculated by using the results obtained in the above mentioned “Florentin” method and free lime determination method. The hydrated product of calcium silicate hydrate xCaO⋅ySiO
2⋅zH
2O in the cases of (2) and (3) siliceous admixtures of common amount of silica (about 69-70%) content was determined to be CaO⋅SiO
2⋅mH
2O having molecular ratio of CaO to SiO
2 (c/s) nearly 1.0, but in the case of the specially high silica (about 94%) content of (1) admixture it was obtained the ratio (c/s)=1.0-2.0, which shows the product of calcium silicate hydrate to be the mixture of CaO⋅SiO
2⋅mH
2O and 2CaO⋅SiO
2⋅nH
2O or 3CaO⋅2SiO
2⋅nH
2O. On the other side, it is doubtful whether the determination of soluble SiO
2, Al
2O
3, and Fe
2O
3 by the “Florentin” method is suitable or not, owing to the fact of colloidal silica separates in the course of treatment with dilute HCl (
d=1.12) solution.
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