Abstract: A commercially useful material is produced from waste gypsum boards containing calcium sulfate dihydrate, by a method comprising the steps of (a) grinding the waste gypsum boards to obtain particles having a substantially uniform size; (b) drying the particles obtained in step (a) to obtain moisture-free particles; (c) heating the moisture-free particles obtained in step (b) at a temperature of 128 to 162.degree. C. to convert the calcium sulfate dihydrate to calcium sulfate hemihydrate; (d) adding water to the particles obtained in step (c) to form a paste; (e) forming the paste obtained in step (d) into a shaped product of a predetermined size; and (f) drying the shaped product obtained in step (e) at a temperature of 105 to 120.degree. C. to obtain a commercially useful material. The materials produced by the method of the invention can be used for a variety of industrial and household purposes.

Abstract: A method of making cement from base metal smelter slag produced by a nickel, copper, lead or zinc smelter, includes crushing the slag with a source of calcium sulphate to a size of less than about 1/4 inch and heating the mixture to produce a cement, and grinding the cement to a size in the range of from about -250 to about 425 mesh.

Abstract: A method for producing cement is disclosed. The method has the advantages that a setting time can be shortened as compared with conventional cement, and a manganese slag can be treated at low cost without giving load to environment, by using the manganese slag which has conventionally been subjected to waste disposal, as a cement raw material. The method comprises using, as a part of cement materials, a manganese slag which is an insoluble component formed in extraction step and refining step in a production of electrolytic manganese dioxide comprising extracting a manganese component from manganese-containing ore, refining a manganese-containing aqueous solution obtained, and conducting electrolytic treatment, to produce manganese dioxide.

Abstract: Disclosed are fibrous mat-faced gypsum boards with improved resistance to skin irritation and itching. The boards include a mat facing in which the fibrous portion thereof comprises both inorganic and organic fibers, with organic fibers preferably being present in amount from about 5% to about 25% by weight of the total fibers.

Abstract: A cement composition comprising fine aggregate, preferably sand, in an amount of about 10 to about 25 wt %; blast furnace slag cement, in an amount of about 20 to about 35 wt %; gypsum, in an amount of about 20 to about 35 wt %; Portland cement, in an amount of about 4 to about 30 wt %; and cement plasticizer in an amount of about 0.3 to about 3 wt %. The dry cement composition may be formulated with aggregate and water to prepare a flowable liquid, self-leveling and self-smoothing coating material that may be applied to a substrate such as a floor substrate. The applied coating requires no manual finishing or smoothing, yet hardens to form a level, very smooth coating that possesses excellent compressive strength.

Abstract: A gypsum mixture is disclosed which has hydrophobic additive substantially uniformly dispersed therein and which comprises gypsum, a first silane of the general formula (RO).sub.3 SiR or of the general formula (RO).sub.2 SiR.sub.2, and a second silane of the general formula (RO).sub.3 SiR' or of the general formula (RO).sub.2 SiRR', wherein each R is the same or different and represents a lower alkyl group, and R' represents a lower alkyl group which is substituted by a substituent selected from an amino, amino-lower alkyl-amino or dialkylenetriamine group. Preferably, the first silane is methyltrimethoxysilane and the second silane is N-(2-aminoethyl)-3-aminopropyltrimethoxysilane. Also disclosed is a method for preparing said gypsum mixture.

Abstract: A method for preparing an aqueous gypsum mixture having hydrophobic additive substantially uniformly dispersed therein, which method comprises admixing in water gypsum, a silane of the general formula (RO).sub.3 SiR' or the general formula (RO).sub.2 SiRR' and non-emulsified polysiloxane of the general formula; ##STR1## wherein each R is the same or different and represents a hydrocarbon group having from one to eight carbon atoms, R' represents a lower alkyl group which is optionally substituted by an amino, amino-loweralkylene-amino or dialkylenetriamine group, and a has an average value of between 20 and 200. The silane is preferably N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and the polysiloxane preferably trimethyl end-blocked linear methylhydrogen polysiloxane. The method may further include adding surfactant. Also disclosed is a gypsum product which includes gypsum mixture prepared according to the above method.

Abstract: This invention relates to a process for preparing ceramic-like materials with specific properties by binding an inorganic filler in the form of a dry composition with a grain size of up to 25 .mu.m containing in the volume ratio 1:0.-1.52 a waste phosphogypsum and magnetite or glass-forming oxides, with an unsaturated polyester resin in an amount of 46-220 volume parts per 100 volume parts of the filler. The use of magnetite makes it poisible to prepare materials with magnetic properties, while glass-foming oxides enable preparing materials effective to absorb an X-radiation of 45-55 keV and a hard radiation of 0.6-125 MeV. When an expanding agent is added to the raw composition according to this invention, an expanded material is obtained, having completely closed pores, particularly useful in the building industry.

Abstract: A novel binder for interior plasters having a calcium sulphate component capable of binding in the presence of water and a finely divided residual material component comprised primarily of calcium sulphite, where the residual material is a product of flue gas desulphurization of coal-fired combustion plants.

Abstract: A new and original water paint is disclosed, in liquid form, such as a milky emulsion, containing a low amount of water and comprising minerals, acetic acid solution, and other components. The new water paint has bactericidal, fireproof, transpiring, ecological, isolating and desalting properties and is suitable to coat manufactured building articles, wood, metals and plastic.

Abstract: The present invention discloses a method for preparing the inorganic hardenable slurry and the use of same in the solidification of wastes. In addition to water, the essential parts of the slurry are inorganic components including borates, cement-base powder and other additives such as magnesium oxide, gypsum and silica. The slurry is low in viscosity before solidification and flows freely,and within approximately 30 minutes after preparation the slurry becomes hardened into a highly solidified substance. The solidification of the slurry is resulted mainly from reaction of borates and the cement-base powder and to obtain a best result the weight of borates must be the same as that of the cement-base powder or even higher than the weight of the latter. The solidification mechanism differs entirely from the simple hydration reaction that brings about solidification of cement.The present invention also teaches a method for solidifying wastes with this hardenable slurry, i.e.

Abstract: A method is provided for making a fiber-reinforced slag gypsum cement lightweight hardened product. The method consists essentially of mixing (1) from 5 to 140 parts by weight of aggregates having a maximum size of not larger than 2000 .mu.m to (2) 100 parts by weight of a mixture which comprises 100 parts by weight of Portland cement, (3) from 20 to 350 parts by weight of slag fine powder which has a fineness ranging from 6,000 to 12,000 cm.sup.2 /g as Blaine's specific surface area, (4) from 0 to 20 parts by weight of lime, (5) from 20 to 100 parts by weight of calcium aluminate and gypsum fine powder, (6) 0.01 to 1.5 parts of a setting retardant; mixing water, prefoamed foams and reinforcing fibers with the mixture to obtain a slurry; subjecting the slurry to molding to obtain a molded product; removing the molded product to obtain a hardened product; and curing the hardened product with steam.

Abstract: Calcium sulfate alpha hemihydrate and foundry sand are milled to cement fineness and form a hydraulic binder, as a mixture with both high early setting strength and excellent water resistance. The composition relies upon a sulfate activation of the foundry sand rather than an alkali activation thereof.

Abstract: A light weight formed body used for building materials, heat-insulating materials, furnitures, backing materials and the like, and a method for producing the same. In the light weight formed body and in the manufacturing method thereof, the principal material is a surface-reformed slag of which the reforming involves reforming through the dissolution reaction and the hydration reaction of glass and the reforming through dehydration of the surface-reformed slag above mentioned under heating, and one or more of a polymer dispersion, a reinforcing fiber, a coagulant, a light weight aggregate, a thickener, a dispersing agent, a pigment, a synthetic pulp, a needle- to fiber-shaped calcium silicate hydrate and a hydraulic gypsum are further used together with the above principal material.

Abstract: Geopolymer-modified gypsum construction materials. Compositions derived from combining geopolymer adhesives with conventional gypsum wallboard slurry formulations produce an interpenetrating network (IPN) which cures by loss of process water to a refractory solid having improved fire and water resistance. Geopolymer adhesive starting compositions includes soluble and insoluble silicates, buffers and salts, and a chemical setting agent in aqueous suspension.

Abstract: A method for treating produced gypsum and, in particular, a method for treating flue-gas desulfurization gypsum forms highly active, modifiable gypsum binders of high strength with simultaneously drying, deagglomerating and dehydrating. Pursuant to the invention, produced gypsum (flue-gas desulfurization gypsum), with a particle size ranging up to 200 .mu.m, to which 10% by weight of milled natural gypsum is optionally added, is dehydrated at a material temperature of 335.degree. to 363.degree. K. and at a pressure ranging from 2.5 to 8 kpa, the dehydration being concluded when anhydrite III constitutes 50% to 100% by weight.

Abstract: A high permeability metal casting plaster is used for production of high accuracy simulated castings for prototypes and any other plastermold castings. Methods are provided that create the high permeability metal casting plaster and mold. Also, a high permeability metal casting plaster is disclosed that uses control ground and screened .alpha.-hemihydrate gypsum such that an average of 100% of the particles have a diameter of no more than 590 .mu.m and an average of 97.3% have a diameter of less that 44 .mu.m, control ground and screened beta-hemihydrate gypsum such that an average of 99% of the particles have a diameter of no more than 270 .mu.m and at least an average of 70% have a diameter of less than 44 .mu.m, sucrose for protection against thermal shock, and a foaming agent. The ratio of .alpha.-hemihydrate gypsum to .beta.-hemihydrate gypsum is approximately 5:2.

Abstract: Blocks, weighing about 35 lbs., formed of a homogeneous mixture of about 75% gypsum and 25% lime, are strategically placed in surface water that is being damaged by acid rain, where, by timed release of lime, the pH of the water is maintained at about 6.5 pH.

Abstract: A process for the production of concrete roofing products of reduced weight loading having a thickness in section of not greater than 15 mm. The process involves forming an asbestos-free cementitious composition comprising (i) lightweight aggregate, (ii) hydraulic cement, (iii) water and (iv) reinforcing fibers in an amount of not more than 4% by weight of the total weight of the composition but the fibers being present in an amount sufficient to provide a reinforcing effect and impact strength in the roofing product, the cementitious composition being capable of being shaped by a roller and slipper method, and thereafter shaping the cementitious composition by the method to provide a shaped extrudate, dividing the extrudate to form sections and curing the sections to provide roofing products, wherein the reinforcing fibers have lengths of 0.5 mm to 20 mm. The impact resistant roofing products are useful as roofing tiles, or a replacement for shingles, shakes and slates.

Abstract: This invention relates to a method of enhancing the later age strength of certain blended cements. Under the process of this invention, certain blended cements, in particular those made from cement clinkers containing at least 4% C.sub.4 AF, when mixed with up to 0.2% of a higher trialkanolamine exhibit a marked increase in 7 and 28-day compressive strengths. The blended cements of this invention contain between 5 and 80% fillers or clinker substitutes. The higher trialkanolamine strength enhancing additive may be admixed with the cement powder or may be interground with the cement clinker during finish milling.

Abstract: The invention provides a method of manufacturing a hydraulic hardening material having the steps of milling vitreous blast furnace slag and classifying the milled slag to provide slag powder having a blaine specific surface area of 6,000 to 12,000 cm.sup.2 /g. The hydraulic hardening material manufactured by the method is used as a Portland blast furance cement raw material.

Abstract: A heat-curing cement composition comprising 60 to 75% by weight of 3CaO.SiO.sub.2, in which the total content of 3CaO.Al.sub.2 O.sub.3 and 4CaO.Al.sub.2 O.sub.3.Fe.sub.2 O.sub.3 is lower than 10% by weight, the alkali content is lower than 0.2% by weight as the Na.sub.2 O equivalent, the balance is composed mainly of 2CaO.SiO.sub.2 and gypsum, and the Blain specific surface area is 3500 to 5500 cm.sup.2 /g. This cement composition provides a hardened body when heat-cured under a high temperature of 35.degree. to 85.degree. C.