3 CaO・SiO_2-Na_2O系固溶体およびアルカリ含有量が異なるポルトランドセメント中のアリットの水和反応

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In order to investigate the influence of alkalies in clinker upon the hydration of alite in portland cement the rate of hydration of 3 CaO・SiO_2-Na_2O solid solution and of alite was measured by quantitative X-ray diffraction analysis. Also the morphological observa-tion of hydrated products was made using electron microscope and comparing the results with those of setting time and strength. Furthermore, 3 CaO・Si0_2 was hydrated in water, and in alkaline solution, and also Jeffery's alite was hydrated in water. The results are summarized as follows : ( 1 ) The initial velocity of hydration of pure 3 CaO・SiO_2,in NaOH solution containing equivalent Na20 to 3 CaO・SiO_2-Na_2O gave the values intermediate between the cases of pure 3CaO・SiO_2 and 3CaO・SiO_2,-Na_2O solid solution. One of the reasons of these observations may be attributed to the difference of activity in hydration caused by the difference of the crystal structure as well as that of the equilibrium in the initial stage of hydration. ( 2 ) The initial rate of hydration of alite in portland cement clinkers was accelerated with increasing amount of alkalies, and was retarded by the addition of gypsum. ( 3 ) Quick set was observed in the hydration of 3 CaO・SiO_2-Na_2O without gypsum. As the formation of the solid solution of alite with alkalies in high alkali clinker is highly probable, and usually the quick set is observed in high alkali clinker, it may be concluded that the quick set occures not only by the vigorous hydration of tricalcium aluminate solid solution, but also by the rapid hydration of alite. ( 4 ) The development of the strength of portland cement clinker increased with the addition of gypsum, and decreased with increasing content of alkalies in clinker. ( 5 ) The influence of alkalies was remarkable only in the initial rate of hydration, which indicates that the rate of diffusion of silicate ion through the gel layer is practically unaffected by the existence of Na+ and K+ in water. ( 6 ) One of the reasons of the inferiority of the strength development in high alkali clinker may be attributed to the decrease of the surface energy by the formation of well crystallized calcium silicate hydrates.
社団法人日本セラミックス協会の論文
1962-05-01

3 CaO・SiO_2-Na_2O系固溶体およびアルカリ含有量が異なるポルトランドセメント中のアリットの水和反応

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