Abstract
The reduction of the firing temperature for artificial aggregate has merit to decrease production cost.
Relating to the physical properties of fired products, the mixing effect of two kinds of ashes that have different properties and the additive effect of calcium carbonate as a flux were investigated.
As results, the partial replacement of a fly ash that is rich in flux elements to a fly ash that is poor in flux elements decreases the firing temperature to obtain maximum density of the latter one, and the hemisphericalizing temperature of ash compact can be estimated by the replacing ratio. The addition of calcium carbonate to fly ash that is poor in flux is effective to decrease the temperature to obtain maximum density, but not effective to the fly ash that is rich in flux.
The appropriate amount of calcium carbonate addition puts the chemical composition into a eutectic point of a CaO-Al2O3-SiO 2 phase diagram. The species of forming mineral in a sintered body is almost the same as those in the diagram.
Though the strength of aggregates is roughly correlative to specific gravity, in detail, the better shape of bubble and the larger amount of melt phase, the stronger the aggregates.
