PURPOSE:To improve slaking resistance and to provide unshaped refractories which can be stably applied by incorporating a binder contg. water glass and bentonite, hydration retarder and water retaining material into a calcareous refractory raw material which is an essential component. CONSTITUTION:For example, a spray coating material is prepd. by using a grain-sized adjusted CaO type refractory raw material, i.e., CaO type clinker as the essential component and incorporating the binder contg. the water glass and bentonite, the hydration retarder and the water retaining material such as fiber material therein. The bentonite powder to be used as the binder has the performance to easily adsorb and retain water when the water is added to the binder at the time of application, in addition to the role of the binder. The water glass cures at ordinary temp. as a binder and contributes to an improvement in strength and the adhesion to a wall surface. The hydration retarder is essentially required to prepare the spray coating material which can be stably used when the spray coating material is rested for several hours on account of a trouble, etc., at the time of the application. Boron oxide, oxalic acid powder, etc., are used for said material. The water retaining material prevents the evaporation of even the moisture necessary for curing of the binder by the abrupt evaporation of the moisture when the spray coating material is sprayed to =150 deg.C wall surface, thereby obviating the degradation in the adhesive strength and the formation of the porous structure.
展开▼
