| 摘要 |
PURPOSE:To improve remarkably the deflection strength of a molding by determining the volumetric ratio of aggregate and binder, coating respectively separately >=2 groups of aggregates having the specified ratio of average grain size with the binder, mixing such groups and obtaining a molding material. CONSTITUTION:The volumetric ratio of the binder with respect to the aggregate is determined in a 0.3-20% range and >=2 groups of the aggregates having >=2<1/2> ratio of the average grain size are respectively separately coated with the binder. A thermosetting phenolic resin is used for the binder and silica sand or the like is used for the aggregate groups. The resin coated sand grains consisting of dry resin-coated sand which has free fluidity at an ordinary temp. The intended molding material is obtd. by mixing such aggregate groups coated with the binder. The deflection strength of the molding is thus remarkably improved. The molding material is used for a casting mold and building material. |
