We examined the characteristics of free lime-hydraulic compound-anhydrite system expansive additive. The clinker structure of free lime-anhydrite expansive additive without hydraulic compound was rough. On the other hand, the clinker structure of free lime-hydraulic compound-anhydrite expansive additive was compact. In addition, the free lime crystal grew large. Compared with the free lime-anhydrite expansive additive without hydraulic compound, the free lime-hydraulic compound-anhydrite expansive additive was excellent in expansion characteristic. Thus, it was clarified that the hydraulic compound played a role to improve expansion performance. It was inferred that the cause of the above phenomenon was deeply related to the structure formation of expansive additive clinker due to the presence of the hydraulic compound. In other words, the presence of the hydraulic compound made the structure of expansive additive clinker compact, and assisted free lime crystal to grow very large, which suppressed the reaction of free lime. we examined also the influence of the preparation method of free lime-hydraulic compound-anhydrite system expansive additive on its performance. The result showed that even thosugh the same composition of additives were used, the expansive additive that was prepared by dispersing the above three compounds into clinker had more excellent expansion performance than the expansive additive that was prepared by mixing the same three compounds. It was considered that these phenomena were originated from differences in the reaction velocity of free lime and formation mechanism of ettringite.

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This study was made to investigate the synthesis and fluorescence property of magnesium substituted calcium carbonate phesphor codoped with Ce³⁺ and Tb³⁺ (calcite phosphor) in order to improve the emission intensity and stability of vaterite phosphor codoped with Ce³⁺ and Tb³⁺ presented in a previous paper. Magnesium substituted amorphous calcium carbonate phosphor codoped with Ce³⁺ and Tb³⁺ (amorphous calcium carbonate phosphor) was synthesized by adding 0.1 mol·dm^-3 (NH₄) ₂CO₃ solution into the mixed solution of 0.1 mol·dm^-3 MgCl₂ solution and 0.1 mol·dm^-3 CaCl₂ solution, which included TbCl₃ and CeCl₃ solution at 35°C. On the other hand, calcite phosphor was obtained by crystallizing amorphous calcium carbonate phosphor at 90°C for 1 hour in the mother liquor. The product was characterized by means of X-ray diffraction, thermal analysis and spectrophotometer.
The amorphous calcium carbonate phosphor and the calcite phosphor emitted green color by black light irradiation. The single phase of calcite phosphor was obtained below Mg/Ca atomic ratio of 0.42. The emission intensity of calcite phosphor was the maximum at this condition, and showed double the vaterite phosphor codoped with Ce³⁺ and Tb³⁺ that was synthesized in the previous paper. The increase of emission intensity was ascribable to a decrease of lattice strain and lattice constant by incorporating Mg²⁺ ion in the calcite structure. The emission intensity of calcite phosphor after thirty days decreased to half its initial value.

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Textured α-tricalcium phosphate (α-TCP; α-Ca₃ (PO₄) ₂) cements were prepared by templated grain growth using platelet-shaped particles of dicalciumu phosphate dihydrate (DCPD; CaHPO ₄·2H₂O) 5-50μm in diameter as a seed material. Both α-TCP and DCPD transformed to calcium deficient hydroxyapatite (Ca_10-x (HPO₄) x (PO₄) _6-x (OH) _2-x) aftercuring in simulated body fluid at 37°C.α-TCP completely disappeared after curing in simulated body fluid at 37°C for 96h, while significant amount of DCPD remained. The morphology of the cement dramatically changed by adding DCPD particles, i. e., the cement without additive consisted of infinite form of fine grains of hydroxyapatite less than 1μm in diameter, while platelet-shaped grains of hydroxyapatite 2-5μm in diameter was uniformly dispersed in the cement matrix by using DCPD template particles. The compressive strength of a cement cured without template at 37°C for 168h was 42MPa, while that prepared by templated grain growth was 74MPa. The improvement of compressive strength seemed to depend on the morphology of hydroxyapatite precipitated in the cement matrix.

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Ceramics for building materials were developed from mixtures of a glass waste, quartzite, and a cemant waste, by firing at the low temperatures around 900°C. The product fired at 900°C possessed more than 30 MPa of bending strength and less than 5% of water absorption. β-wollastonite persisted in the specimens fired up to 1200°C and no α-wollastonite was formed at the temperature. β-wollastonite was formed on the surfases of quartz grains that were used as fillers and quartz grains were not transformed to cristobalite below 950°C.

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The thermal behavior of synthetic gyrolite, Z-phase and their products, H30-synthetic gyrolite and H40-Z-phase of which interlayer cations were removed with acid was examined on XRD, TG-DTA-MS and spectrophotomater. Crystal structures for synthetic gyrolite and H30-syn. gyrolite heated at 600°C and for Z-phase and H40-Z-phase heated at 650°C closely resembled that of truscottite and that of K-phase, respectively. For H30-syn.gyrolite and H40-Z-phase, the color changes from white to light brown at the temperatures of 250°C to 400°C and the hydrogen release occured at the temperatures of about 600°C to 850°C. But for syn.gyrolite and Z-phase, the color change and the hydrogen release never occured on heating.

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