It is well known that the aggregate containing montmorillonite suppresses the flowability and accelerates the setting of concrete. In this study, the influence of such aggregate on the early hydration of cement was investigated and the mechanism of flow loss of fresh mortar was discussed.
The fine aggregate containing montmorillonite used in this study shows a remarkable adsorption of OH^- and K⁺ ions. Immediately after the mixing, the saturation degree of Ca (OH) ₂ in liquid phase of mortar was extremely depressed by using this aggregate. Consequently, the initial hydration of interstitial phase was accelerated and the monosulphate hydrate formed with ettringite. After that, the saturation degree of Ca (OH) ₂ increased rapidly and the monosulphate hydrate was converted to the ettringite. It is considered that the remarkable flow loss of the mortar using this aggregate after one hour is due to the rapid conversion of monosulphate hydrate to the ettringite with large cohesive energy.

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Calcium-aluminate glass with different chemical compositions was prepared, and the effects of the chemical compositions of calcium-aluminate glass on the hydration and the properties of the hardening accelerator were discussed. In this study, ordinary Portland cement and the hardening accelerator were mixed, and the behavior of setting and hardening, the amount of hydration products and the ions concentration in the solution were measured. The results obtained are as follows;
(1) The behavior of setting and hardening were influenced considerably by the CaO/Al₂O₃ molar ratio of calcium-aluminate glass. When that ratio was higher, the plasticity of the mixture was lost faster, and the succeeding hardening was faster as well. It is suggested that these changes of properties of mortar were caused by the rapid formation of ettringite from calcium-aluminate glass and anhydrite.
(2) The ions concentration in the solution changed considerably, and both of Ca⁺ and SO₄^2-were decreased rapidly when the formation of ettringite began. On the other hand, Al³⁺ increased temporally when the CaO/Al₂O₃ molar ratio was lower, because Al₂O₃ was oversupplied to form ettringite. Subsequently the concentration of Al³⁺ fell.
(3) It is suggested that the excess Al³⁺ was consumed and alumina-gel or Al-rich gel formed. It is also suggested that these gel type hydration products raised the strength at the very early stage.

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In order to study the water cleansing properties of porous concrete and the influence of calcium ion solution, tests were conducted both in beakers in the laboratory and at a field sea area.
The results obtained are as follows;
1) Calcium ions of porous concrete are easily dissolved in sea water, about 0.5% of the total volume of porous concrete being soluble in sea water of ten times the weight.
2) Calcium ions and alkaline ions are dissolved from porous concrete. The calcium ions act to precipitate phosphate ions as calcium salt, and the alkaline ions are a necessary element in this precipitation.
3) From the results of examination in the field sea area, it was found that phosphorus and phosphate ions had accumulated in the specimen.

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The special cement designated as Ecocement, which has been developed to utilize municipal waste as a raw material, contains several hundred times as much amount of chloride as oridinary portland cement does.
This paper forms a part of the investigation on applying this cement to a soil stabilizing agent. On its application to this field the chloride eluted during hydration of this cement was concerned about the influences on underground steel structures and quality of underground water. In order to reduce amounts of chloride elution, the effects of adding blast furnace slag to the cement were investigated by means of conducting chloride elution test, compressive strength test, x ray diffraction analysis and observation with scanning electron microscopy. Furthermore the applicability of the cement to a soil stabilizing agent was estimated by compressive strength tests on the improved soil. The results are summarized as follows.
1) The amount of chloride eluted from cement paste can be reduced to about 50% by mixing blast furnace slag and the cement in the weight proportion 1 : 1.
2) The addition of blast furnace slag gives rise to higher compressive strength of cement paste and improved soil than the neat cement.

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Limestone powders are widely investigated in connection with filler cement for ecological materials and functional cement for flowing concrete. However, there are still many unclear points concerning the reaction mechanism and the amounts of limestone powder reacted.
This paper discuss the hydration of various calcium aluminates with CaCO₃·CaCO₃ reacted with various types of calcium aluminates and produced mainly C₃A·CaCO₃·11H₂O. In C₃A-CaCO₃ system, the molar ratio of production amount of C₃A·CaCO₃·11H₂O and the amount of CaCO₃ reacted were 1.0. But in the case of C₁₁A₇·CaF₂-CaCO₃ or C₁₂A₇ glass?CaCO₃ system, this molar ratio was 0.53. In these system, the gel containing CaCO₃ may be produced.

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From the viewpoint of economically removal and recovery of phosphorus ions in waste water, anion-exchange characteristics of pyroaurite-like layered double hydroxides [Mg_0.79Fe_0.21 (OH) ₂ Cl_0.19 (CO₃) _0.01·mH₂O] (Mg, Fe-Cl) for phosphate, phosphite and hypophosphite anion have been investigated by a batch method in aqueous solution at 25°C. The anion-exchange amount of phosphate ion on the Mg, Fe-Cl is affected considerably by the pH of aqueous solution and has a maximum around pH 7.5. It was found that the Mg, Fe-Cl has high removal and selectivity characteristics for phosphate and phosphite anions, but hypophosphite anion can hardly anion-exchanged by the Mg, Fe-Cl. The Mg, Fe-Cl is promising as a new removal agent for phosphorus ions in waste water.

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Gas temperature and gas-velocity distributions in a propane-oxygen flame as well as the progress of fusion of ground natural quartz powder along the flame were examined using two types of burners : burner-A is a conventional burner for thermal gunning and burner-B is a burner designed for the preparation of spherical particles. The vitrification ratio of samples obtained at the flow rates of propane and oxygen gases of 5 and 17.5 Nm³/h, and the powder feed rate of 10 kg/h and the flow rate of oxygen carrier gas of 7.5 Nm³/h by using the burner-B was as high as 94%, while that was 43% in the case of burner-A. Furthermore, although appreciable vitrification ratios were observed only for particles from the narrow central part of the flame of burner-A, the fusion of particles was found to occur in the wide region of flame of burner-B. These observed facts are coincided with the calculated temperature rise of a particle in the flames. The difference in vitrification ratio is attribute to the longer residence time in the high temperature region for the burner-B than that for the burner-A because of wide high temperature region and low particle velocity in the burner-B.

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Effect of water on CO₂ absorption capacity of lime mixture which is used for absorption agent. There are some effects of water on absorption efficiency of hydrated lime as follows.
a. As increase in water content of lime mixture, CO₂ absorption capacity of mixture was increased.
b. As decrease in density of lime mixture, CO₂ absorption capacity of mixture was increased.
c. The highest CO₂ absorption capacity of lime mixture was shown at 15 weight% of water content.

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The amount of municipal solid waste incineration ashes (MSW ashes) generated in Japan annually has reached approximately 6 million tons. Considering the shortage of final disposal area, the development of excellent utilization methods is desired. ECOCEMENT, which is the special cement made from MSW ashes, contains alinite or calcium-chloroaluminate including chlorine in MSW ahes. ECOCEMENT could be called as a kind of cement to keep the coexistence between mankind and environment.
In this report, in order to investigate the properties of the soil improved by ECOCEMENT, unconfined compressive strength tests, leaching tests and elution tests were conducted. The results are summarized as follows ;
(1) The unconfined compressive strength of the soil improved by ECOCEMENT reached about eighty to one hundred-fifty percent of that by ordinary portland cement at one year age.
(2) On leaching out chloride ion from the soil improved by ECOCEMENT, the diffusion rate at 91 day age was below one tenth of that at 3 day age.
(3) The quantity of heavy metals eluted from the soil improved by ECOCEMENT could satisfy the values of I-grade upon Japanese Soil Environmental Standard.

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