Effects of the addition of silica fume (SF) and sodium polyacrylate (PANa) on the hydration of slag-alkali cement (SAC) based on NaOH solution were discussed from the data of hydration products and compositional changes in liquid phase. The following conclusions were obtained.1) In the system of slag-H₂0, reactivity of slag is very low because of the low concentration of the elements in the liquid phase. The concentration had reached just over the saturated concentration of hydrates after a few days.2) By using NaOH solution, the concentration of Al (OH) ₄^-ion was kept very high. From the solution, C-S-H was first produced and the formation of crystalline aluminate hydrate was followed.3) In the system of NaOH solution with and without PANa, CS-H, C₃ASH₄, AFm and Ca (OH) ₂ were produced.4) Addition of SF resulted the higher concentration of SiO₄^4-ion and Al (OH) ₄^-ion, and accelerated the formation of C-S-H.5) The addition of PANa accelerated the formation of C-S-H without raising the concentration of SiO₄^4-ion in liquid phase. It also prevented to produce the aluminate hydrates.

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It is very important problem for the utilization of waste bottle glass which is discharged a large quantity, and will be increasing. The best method of utilization of it possessing the pozzolanic reactivity, is considered to use for addmixtures of portland cement or silica resources of hydrothermal reaction with cement. In this study, portland cement in the addition of waste bottle glass powder was hydrothermally treated in the autoclave at 180°C, and the process of the hydrothermal reaction in the system of portland cement and glass was discussed to measure the compressive strength, produced hydrates and reaction rate of the glass. The results obtained are as follows.
1) A large quantities of C-S-H and tobermorite were produced in the sample of the glass addition, for the reason of pozzolanic reaction of glass and cement. The large compressive strength was obtained for the 30-50% of glass addition samples.
2) Waste bottle glass powder could be used for silica resources of hydrothermal reaction with cement. The alkali compornents dissolve with the glass reaction. It will be needed to more studies of the affects of alkali on the systems for the utilization of waste glass.

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パイロライト様層状化合物Mg_1-xFe_x (OH) ₂ (C1, CO₃) y・nH₂0を湿式および水熱法で合成し, それら合成物のNO₃^-に対するイオン交換特性を検討した。化合物はNO₃^-に対して高選択性を示した。とくに水熱法での化合物はNO₃^-に対する選択性がすぐれているのみならずCO₃^2-含有量も少なく結晶性も良かった。CO₃^2-の含有量は化合物のイオン交i換特性に大きな影響を示すことが判明した。合成物は水中の有毒イオンであるNO₃^-の除去剤として有望であると考えられる。

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The grain growth rate of pure MgO and 1% alumina doped MgO was measured at 1500-1700°C in air. The time dependence of grain growth in pure MgO was 1/2 during sintering at 1700°C. On the other hand, that of grain growth in 1% alumina doped MgO was expressed in the equation of X⁴-X₀⁴=Kt, which was theoretically derived here. The activation energy calculated from experimental data of grain growth in 1% alumina doped MgO was 116 kcal/mol, which was fairly good agreement with that of volume diffusion of oxygen ion in spinel.

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On crystallyzation of CaCO₃ from Ca (NO₃) ₂ aqueous solution by a homogeneous precipitation technique using urea, the effect of Ni²⁺ and Co²⁺ ions on morphology and coloring of CaCO₃ was studied at 70-90°C. Ni²⁺ and Co²⁺ ions in the mother solution suppressed the transformation of needle-like aragonite into calcite effectively more than Mg²⁺ ion and inhibited the growth of aragonite, resulting in small particles of aragonites. The possibility was suggested that Ni²⁺ ion forms a solid solution with calcite and that Co²⁺ ion does with aragonite.

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