A sand additive for use in a “no bake” foundry mix composition having a polyurethane-based binder system reduces the amount of smoke emitted when molds and cores formed from the composition are exposed to molten metal, as compared to when the sand additive is not used. The sand additive comprises yellow iron oxide having the chemical formula Fe(OH).sub.3. It can also comprise at least one of red iron oxide, black iron oxide and wüstite. In such cases, the yellow iron oxide accounts for about 10 to about 40 weight percent of the combined weight of the yellow iron oxide, red iron oxide, black iron oxide and wüstite, and preferably, about 20 to about 30 weight percent of the combined weight of the yellow iron oxide, red iron oxide, black iron oxide and wüstite.

A curing agent for water glass molding comprises: ester; amorphous silica; and water. The amorphous silica is formed by means of a pyrolysis method and/or by means of a precipitation method. Also disclosed is a use of the curing agent for water glass molding in preparation of a casting mold and a mold core. Respective components of the curing agent comprising ester, amorphous silica and water are mixed at a high speed to form a suspension. Next, the suspension is applied to prepare a water glass self-hardening sand. The curing agent does not cause powder contamination, and can be measured and added conveniently. Also disclosed are a manufacturing method of the curing agent for water glass molding and a water glass self-hardening sand.

Casting of non-ferrous metals, especially aluminum and magnesium, can have problems with erosion, in which molten metal contacts the mold or core surfaces during the pouring process, resulting in the sand being dislodged. Binder systems addressing this issue often use bisphenol F epoxy resin. A binder system is provided in which a major portion of the epoxy resin component is a bisphenol epoxy resin that has been modified by incorporating oxazolidone rings into an epoxy backbone of the bisphenol epoxy resin, especially a bisphenol A epoxy resin. The modification is preferably achieved by reacting the diglycidyl ether of the bisphenol with a methylene diphenyl diisocyanate.

A hydraulic composition for an additive manufacturing device has an excellent initial flexural strength development property and dimensional stability. The hydraulic composition includes 1.5 to 14 parts by mass of a polymer with respect to 100 parts by mass of an inorganic binder. In addition, in a hydraulic composition for an additive manufacturing device, the inorganic binder may contain 50 to 100 mass % of a calcium aluminate with respect to 100 mass % of the entire inorganic binder, and in a hydraulic composition for an additive manufacturing device the inorganic binder, may contain 0 to 50 mass % of rapid hardening cement with respect to 100 mass % of the entire inorganic binder.

A molding material in a powder-fixing lamination method includes an aggregate and a powdery precursor of a binder that binds the aggregate mutually. The aggregate is a casting sand, and the powdery precursor contains a hardening component and a hardening accelerating component. A molded product is manufactured using the molding material.

In one aspect, a pottery plaster formulation with increased water absorption, comprising alpha stucco, continuously-calcined-in-a-kettle stucco, and a combination of Rochelle salt and one or more of the following: potassium sulfate and/or a phosphate compound. In another aspect, pottery plaster molds with increased water absorption and methods of making and using the pottery plaster molds for slip casting ceramic items.

The present invention is directed to a construction chemical composition for the preparation of gypsum articles, said construction chemical composition comprising fine calcium sulfate and a dispersant being a polyarylether. Further the present invention is directed to a process for preparing said construction chemical composition as well as an article comprising said construction chemical composition.

Provided are: a coated sand having improved fluidity and being capable of improving a filling rate of a casting mold to be obtained; and a coated sand for advantageously manufacturing a casting mold having excellent strength, which coated sand provides a casting mold with good mold-releasability and collapsibility, gives cast products a favorable casting surface, and effectively improves sand adhesion on cast products. The coated sand is formed as a dry granular material having fluidity at room temperature, in which the surface of a refractory aggregate is coated with a solid layer of a water-soluble inorganic binder, and spherical particles of silicone resin having binder-repellency exist on the surface of the binder layer, or form a layer on the surface of the binder layer, a part of the spherical particles being not covered with the water-soluble inorganic binder and being exposed.

A method of forming a lightweight polished concrete and the resulting composition. Calcium sulfoaluminate (CSA) cement and specialized grout may be added to an amount of water in a mixer. The CSA cement, specialized grout, and water may be blended to a smooth consistency. Lightweight aggregates (LWA) may be added to the blended CSA cement, specialized grout, and water to form a mixture. The mixture may be poured over a fiberglass rebar, vibrated, screeded, and allowed to set. The set mixture may be smoothed with float blades. The smoothed mixture may be hardened with metal blades, such that the hardened mixture becomes reflective. A concrete densifier may be applied to the hardened mixture to form the lightweight polished concrete. Optionally, one or more saw cuts may be formed in the lightweight polished concrete and a coating to may be applied to fill the one or more saw cuts.

A method of forming a lightweight concrete block and the resulting structure. Calcium sulfoaluminate (CSA) cement and specialized grout maybe added to an amount of water in a mixer. The CSA cement, specialized grout, and water may be blended to a smooth consistency. Lightweight aggregates (LWA) maybe added to form a mixture. The mixture may be poured into a mold, allowed the mixture to cure, and removed from the mold to form the lightweight concrete block. The lightweight concrete block may have a first side and a second side joined by a plurality of interposing walls, the interposing walls defining one or more inner cavities and one or more outer cavities. The lightweight concrete block may have features that allow for the insertion of fiberglass rebar to aide in stacking and filling to form a wall.