Alumina cements were manufactured as experiments from aluminium dross ashes and oyster shells. Aluminium dross ashes were oxidized by burning treatment at 1100°C, and oyster shells dried at 110°C. The mixture of pretreatment aluminium dross ashes and oyster shells were crushed in a grinding mill. Alumina cements were obtained by burning ground mixtures. Mixing ratio of these wastes were designed to be 0.25-4.0 CaO/Al2O3 mass per cent, and the burning conditions were set to be 1100-1300°C. Alumina cements were characterized by means of XRD and XRF, and the refractoriness were examined in accordance with JIS R2204. Compressive strength of hardened mortar was examined in accordance with JIS R2521.
The results obtained from the present study are as follows.
1) Main components of alumina cements were CA, MA, and C2AS. The formation of CA was confirmed by burning at 1100-1300°C and set to be 0.43-0.67 CaO/Al2O3 mass per cent.
2) Compressive strength of hardened mortar reached at 51.4 N·mm-2 in 28 days. The refractoriness of alumina cement reached at roughly 1500°C. There seems to be a chance that alumina cement can be used for refractory brick, unreinforced concrete and so on.
