Fly ash cement was manufactured for trial with the mixture of the fly ash subjected to hydrophobic surface treatment and Portland cement. Physical properties which were focussed on the properties of setting in the paste of the cement and the flowability in mortar were evaluated. As a result, it was found that most of all water repellent agents has a character of improving flowability of mortar. Some water repellent agents affected on the increase of viscosity which related to the zeta-potential of fly ash. However, the action is inferior to that of thickener. Moreover, setting time of paste was delayed with some kind of water repellent agents.
The utilization of industrial materials waste, municipal refuse, sludge or their incinerated ashes as raw materials for cement has recently begun. This paper discusses mineral composition and pozzolanic reactivity of incinerated ashes of sewage sludge. Main mineral compositions of incinerated ashes of sewage sludge are glass phase containing P2O5, α-quartz and plagioclase. Incinerated ashes are reacted with Ca (OH) 2 and its pozzolanic reactivity is higher than that of ground blast furnace slag. Pozzolanic reactivity of incinerated ashes of sewage sludge is related to the contents of glass phase and mean particle size.
This paper discusses the influence of copolymerization composition of comb-type superplasticizers on adsorption and dispersion mechanisms, and their subsequent effect on the fluidity of concentrated limestone powder suspensions. The saturation absorbed amount of the polymer increases, when the substitution ratio of sulfonate group increases. However, the adsorption form changes, and the thickness of adsorbed polymer may be decreased with sulfonate group substitution ratio. When polymers containing sulfonate groups are adsorbed on particles, the zeta-potential of the particles shows the negative value. However, the electrostatic repulsive force in which not sufficient value cannot disperse the particle. In these polymers, the dispersion of the particle is caused by effect of steric hindrance of adsorbed polymer. In the polymer for this study, it is possible to have the disperse performance, which is equivalent to the polymer without the sulfonate group to sulfonate group substitution rate of about 50%.
To develop a decomposition processing system of halon that is a destruction compound of ozone layer and also a substance for global warming, the decomposition conditions, composition of reactant, and reaction temperature were investigated. From the examination of ratio of CaO to MgO in the reactant, it was found that the optimum ratio for the decomposition of halon was CaO : MgO = 75 : 25. Then, we choose a light burnd dolomite that had the close ratio of the above as a practical reactant. The decomposition efficiency of halon and the decrease of the formation of fureon116 (hexafluoroethane) that was a by-product in the decomposition process, were investigated by using the reactant. It was found that the decomposition efficiency of halon was over 99.99% and the formation of fureon116 was less than 0.0001% in the temperature rangeover 900°C. The similar results were obtained in the experiment using a continuous decomposition apparatus equipped with a vertical furnace. A practical decomposition process of halon with light burnt dolomite was established.
Sealing treatment made by sol-gel process using a multi-component solution consisted of organic silicon compound and silica sol was applied to the ceramics for the filling of the pores and coating on the surface. SEM observation, pore size distribution determination, solid 29Si-NMR measurement, and the measurement of the air permeability of the ceramics were carried out on the samples before and after treatment in order to verify the effect of the sealing treatment. Results showed that the sol introduced into the pores formed silica glass, filled them and coated on the surface, therefore improved the air tightness of the alumina ceramics.