Abstract: The present invention describes improved anhydrite cementitious compositions that control or avoid ettringite formation, as well as procedures for manufacture. These compositions exhibit good compression resistance in early stages, good resistance to abrasion and good behavior under water.

Abstract: A composition including two components is provided. When the two components are admixed in the method of the invention a polymer-modified gypsum composition is provided. The admixture exhibits a useful balance of setting time and stability.

Abstract: A gypsum composition containing a sulfonate-containing comb-branched copolymer is disclosed. The sulfonate-containing comb-branched copolymer comprises recurring units of a polyether macromonomer, an acrylic monomer, and a sulfonate monomer. The sulfonate-containing comb-branched copolymer not only increases the fluidity of gypsum slurry but also has reduced retardation on the gypsum setting.

Abstract: The present invention relates to methods of stimulating a subterranean formation. More particularly, but not by way of limitation, the present invention relates to methods of fracturing subterranean formations utilizing a fracturing fluid comprising a permeable cement composition that may be used as a propping agent. One method of stimulating a subterranean formation of the present invention comprises the following steps: preparing a permeable cement composition comprising a hydraulic cement, water, and a degradable material capable of undergoing an irreversible degradation downhole; injecting the permeable cement composition into the subterranean formation at a pressure sufficient to create a fracture in the subterranean formation; and allowing the permeable cement composition to form a proppant matrix having voids in the fracture.

Abstract: A magnetic device and method for making it involve a magnetic device specifically constructed of grains in a matrix. The matrix may be cement or plaster. The grains have an average diameter that is greater than their magnetic domains. The device may be applied to shielding applications for frequencies ranging from 100 kHz to 10 GHz. The shielding may be applied to walls of a building, consumer products such as magnetic disks, and the like. The grains may be any ferromagnetic material, including ferrite.

Abstract: Disclosed is an improved alpha calcium sulfate hemihydrate. Methods of producing an improved powdered calcium sulfate hemihydrate (CaSO4·½H2O) [alpha-type] compound are disclosed, at least one method including forming calcium sulfate dihydrate (CaSO4·2H2O) into a briquette under high pressure, calcining the briquette to transform the calcium sulfate dihydrate to calcium sulfate hemihydrate [alpha-type], drying the calcium sulfate hemihydrate [alpha-type] briquette, and optionally grinding the briquette. Also disclosed are methods of producing an improved gypsum plaster including producing the disclosed powdered calcium sulfate hemihydrate [alpha-type] and mixing the powdered calcium sulfate hemihydrate [alpha-type] with water.

Abstract: The present invention relates to a computational tool that allows to evaluate the degradation of cement-based materials under various types of chemical attacks such as sulfates, chlorides, and plain water. It is based on the physical principles of ionic mass conservation and chemical equilibrium between a solution and different solid phases. The effect of the dissolution or the precipitation of solid phases on the transport coefficients is considered. A method for determining an ion concentration in solution of at least two ions capable of undergoing transport in a cement-based material under a chemical attack and a solid phase profile for at least one component of said cement-based material is provided. A method for determining a diffusion coefficient for each of at least two ions capable of undergoing transport in a cement-based material is also provided.

Abstract: A method for making a gypsum product water resistant, the method comprising adding a suspension of a hydrophobic substance to a gypsum slurry.

Abstract: A composition and method for treating a surface is described. In one embodiment, the composition comprises about 10% to 90% by weight of cement, about 10% to 90% by weight of plaster, about 0.01% to about 20% by weight of lime, and about 0% to about 30% by weight of perlite. In another embodiment, the composition comprises plaster, cement, perlite, lime, joint compound and water, wherein the plaster, cement, perlite, and lime are in a ratio of about 10-90: 10-90: 0-30: 0.01-20 by weight. In another embodiment, the composition is prepared by a method comprising: (a) providing a first mixture comprising plaster, cement, perlite, and lime; (b) converting the first mixture to a second mixture by a method selected from the group consisting of stirring the first mixture, passing the first mixture through a strainer, and milling the first mixture; and (c) mixing the second mixture with joint compound and water to obtain the composition.

Abstract: A method comprising adding a suspension of a hydrophobic substance to a gypsum slurry. The hydrophobic substance may impart water repellent characteristics to the gypsum, may be used as a foaming aid, density reducer, dimension stabilizer, and others, and may increase the mechanical strength and durability of the gypsum product. In another embodiment of the present invention, suspensions of other substances may be used in addition to or in place of the hydrophobic substance to impart these characteristics.

Abstract: A mold-resistant gypsum panel includes a core of an interlocking matrix of calcium sulfate dihydrate crystals, a facing material on at least one side of the panel and a salt of pyrithione dispersed through both the core and the facing materials. A method of making a mold-resistant gypsum product is also provided. A slurry of calcined gypsum, water and a water-soluble pyrithione salt is formed, then deposited on a sheet of facing material. The slurry on the facing material is shaped into a panel and maintained under conditions sufficient for the calcined gypsum to react with the water to form a core comprising an interlocking matrix of set gypsum crystals. Heating of the panel causes evaporation of the water that did not react with the calcined gypsum.

Abstract: The present invention refers to a mixture comprising alpha CaSO4×½ H2O, CaSO4×2 H2O, a combination of a hardening accelerator, a hardening retarder and a setting expansion inhibitor, and optionally a surfactant. The mixture can be used to prepare a die having an extremely high setting expansion.

Abstract: Disclosed is a mold material for metal casting capable of suppressing the deterioration of cast metal. The mold material for metal casting contains hemihydrate gypsum and a heat resistant material, wherein an oxoacid salt of phosphorus, insoluble in water, is contained in the mold material.

Abstract: An injectable resorbable bone graft material, and methods of using the same, provide increased compressive strength after injection in a bone defect. The bone graft material is made from calcium sulfate hemihydrate having a thick stubby rod-like crystalline structure and low water-carrying capacity.

Abstract: The invention provides a set gypsum-containing product having increased resistance to permanent deformation and a method for preparing it comprising forming a mixture of a calcium sulfate material, water, and an appropriate amount of one or more enhancing materials chosen from condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units. The mixture is then maintained under conditions sufficient for the calcium sulfate material to form a set gypsum material.

Abstract: Disclosed is an improved alpha calcium sulfate hemihydrate. Methods of producing an improved powdered calcium sulfate hemihydrate (CaSO4.½H2O) [alpha-type] compound are disclosed, at least one method including forming calcium sulfate dihydrate (CaSO4.2H2O) into a briquette under high pressure, calcining the briquette to transform the calcium sulfate dihydrate to calcium sulfate hemihydrate [alpha-type], drying the calcium sulfate hemihydrate [alpha-type] briquette, and optionally grinding the briquette. Also disclosed are methods of producing an improved gypsum plaster including producing the disclosed powdered calcium sulfate hemihydrate [alpha-type] and mixing the powdered calcium sulfate hemihydrate [alpha-type] with water.

Abstract: A plaster formulation for forming a non-shinny, slow-drying plaster, in which color may be blended and multiple color coats applied to form a colored surface with the appearance of depth, age, and texture.

Abstract: Disclosed are formulations adapted to form a foamed cementitious composition, the foamed cementitious composition itself, a method of forming a hydraulic binder foam, and a method of conveying and applying the resulting foam to a substrate. A pumpable cementitious slurry is formed, the slurry is mixed with a gas such as air, and is subjected to mechanically created turbulence to generate gas bubbles and create a foam, which preferably is stabilized by a foam stabilizing agent such as polyvinyl alcohol present in the slurry. The foam is then conveyed to a nozzle or other suitable dispense point from which it is applied, for example sprayed, preferably uniformly, onto a substrate to be coated. Prior to dispensing, a set accelerator is preferably injected, which causes the foam to gel, which in turn improves the hangability of the product on a substrate. The spray material adheres to the substrate and hardens to form an insulative coating on the substrate.

Abstract: A gypsum wallboard that exhibits antimicrobial characteristics is disclosed. A method for making the wallboard is also disclosed. Suitable antimicrobial agents that may be applied to the wallboard or any components thereof include propiconazole, sodium pyrithione, tolyl diiodomethyl sulfone; tebuconazole; thiabendazole; 3-iodo-2-propynyl butylcarbamate; and mixtures thereof.

Abstract: A method for increasing the drying rate of set plaster by adding fatty alcohol sulfate to the slurry of calcium sulfate hemihydrate from which the plaster is made.

Abstract: A rough-surfaced substrate, such as a fiberboard, is provided with a smoother surface by applying a coating comprising calcium sulfate hemihydrate which has been prevented from hydrating to gypsum by set preventer, and which sets when brought into contact with a set initiator, e.g. aluminum sulfate, preferably present on the surface of the substrate.

Abstract: The present invention relates to a method of preparing a hydraulic binder wherein at least the following two binders are mixed together: a) a first hydraulic binder having as one of its main components the mineral compound C4A3{overscore (S)}; and b) a sulfate second binder based on calcium sulfate hemihydrate and/or anhydrite obtained by applying heat treatment to gypsum. The present invention also provides a binder comprising amongst its main components: a) a mineral compound C4A3{overscore (S)}; and b) a compound comprising a hemihydrate of calcium sulfate of &agr; or &bgr; form and of general formula CaSO4, ½H2O and/or an anhydrite of III form of general formula CaSO4, &egr;H2O with &egr; lying in the range 0 to 0.5, preferably in the range 0.06 to 0.11, or an anhydrite of II form of formula CaSO4.

Abstract: It is an object of the present invention to provide a portland cement substitute which shows no deterioration of various characteristics (e.g., bending strength) even when incorporated with chips or wastes discharged from a hard cemented chip board production process at 20% by weight or more to reutilize them, method for producing the same easily and economically, hard cemented chip board comprising the same, and method for producing hard cemented chip boards comprising the same.

Abstract: Dry mortar formulations comprising a) from 0.5 to 80% by weight of hydraulic binder, b) from 0 to 97% by weight of fillers, c) from 0 to 3.5% by weight of thickeners, d) from 1.0 to 80% by weight of redispersible polymer powder, and e) from 0.0001 to 1.0% by weight of antioxidants exhibit improved tensile strength and other set mortar properties, particularly after storage of the dry mortar composition.

Abstract: A process for synthesizing a hydraulic binder based on natural calcium sulfate (gypsum), the process consisting in heating the calcium sulfate to obtain a large proportion of anhydrite III or &agr; anhydrite, and then in quenching. The process consists in: completely dehydrating the calcium sulfate, and suddently cooling the matter thus dehydrated. The present invention finds a preferred application in the construction industry in obtaining a hydraulic binder that can be used as cement.

Abstract: The invention provides a method of providing void spaces in gypsum wallboard and in a gypsum core composition such that the weight of the gypsum product is reduced without deleteriously affecting its mechanical properties. More specifically, the invention provides a method of providing void spaces in a gypsum wallboard comprising the step of adding air bubbles having different relative stabilities to a gypsum slurry, wherein the less stable air bubbles are sufficiently unstable such that they coalesce on contact with each other in the slurry to form larger air bubbles, and the weight ratio of the less stable air bubbles to the more stable air bubbles initially added to the slurry is such that there are a sufficient number of more stable air bubbles to prevent a majority of the less stable air bubbles from becoming large enough to rupture before the slurry sets sufficiently to prevent the slurry from filling void spaces left by ruptured bubbles.

Abstract: I provide a multi-part aqueous gypsum dental casting composition having gypsum and water and wherein (a) one or more of a first compound is mixed in the gypsum and/or water; or (b) one or more of the first compound and one or more of a second compound are mixed in the gypsum and/or water; or (c) one or more of the first compound and one or more of an acid are mixed in the gypsum and/or water; or (d) one or more of the first compound and one or more of the second compound and one or more of the acid are mixed in the gypsum and/or water; or (e) two or more of the acids and optionally one or more of the second compound are mixed in the gypsum and/or water; and (f) the gypsum and water are maintained separately and mixed when the casting is to be prepared. Also provided are the dosage sized containers for the above, along with the dosage size containers having gypsum enhancers.

Abstract: The present invention refers to a mixture comprising alpha CaSO4×½H2O, CaSO4×2H2O, a combination of a hardening accelerator, a hardening retarder and a setting expansion inhibitor, and optionally a surfactant.

Abstract: An organic substrate is manufactured from recycled waste paper, cotton fiber and cotton gin waste, and gypsum. The recycled waste products are combined to form a slurry mixture for processing by conventional paper making machinery into a substrate that may be used in sheet form or comminuted pieces.

Abstract: A method for increasing the drying rate of set plaster by adding fatty alcohol sulfate to the slurry of calcium sulfate hemihydrate from which the plaster is made.

Abstract: Structural components for a fire door comprising a core and edge banding and other structural components, the components comprising gypsum, expanded perlite, and cement, and having a density between about 60 and 80 lbs./ft.3. Also, a method by which the structural components are made and a fire door comprising the components.

Abstract: The present invention provides methods, lightweight well cement compositions and additives for the well cement compositions. The methods of the invention for sealing pipe in a well bore penetrating a zone or formation which readily fractures at low hydrostatic pressure is basically comprised of the steps of providing a lightweight cement composition comprised of a hydraulic cement, water and an additive comprising a suspension of microspheres in water gelled with sodium bentonite, placing the cement composition in the annulus between the pipe and the well bore and allowing the cement composition to set.

Abstract: A rapid setting cementitious composition useful for making cement boards employs an insoluble form of anhydrous calcium sulfate (anhydrite) to accelerate setting and to permit reducing the amount of high alumina cement usage.

Abstract: The invention provides a set gypsum-containing product having increased resistance to permanent deformation and a method for preparing it comprising forming a mixture of a calcium sulfate material, water, and an appropriate amount of one or more enhancing materials chosen from condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units. The mixture is then maintained under conditions sufficient for the calcium sulfate material to form a set gypsum material.

Abstract: The lightly colored sulfoaluminous clinker contains:

Abstract: Coating compositions and methods of their use are described herein for the reduction of corrosion in imbedded metal structures. The coatings are applied as liquids to an external surface of a substrate in which the metal structures are imbedded. The coatings are subsequently allowed to dry. The liquid applied coatings provide galvanic protection to the imbedded metal structures. Continued protection can be maintained with periodic reapplication of the coating compositions, as necessary, to maintain electrical continuity. Because the coatings may be applied using methods similar to standard paints, and because the coatings are applied to external surfaces of the substrates in which the metal structures are imbedded, the corresponding corrosion protection may be easily maintained. The coating compositions are particularly useful in the protection of metal-reinforced concrete.

Abstract: Methods and compositions for sealing subterranean zones penetrated by well bores are provided. The methods basically comprise the steps of introducing a sealing composition into the subterranean zone comprised of a hydraulic cement, sufficient water to form a slurry and a rapidly acting thixotropy providing gelling agent, and allowing the sealing composition to remain at rest in the zone whereby the sealing composition rapidly gels and then sets into a hard impermeable mass therein.

Abstract: A manufactured granular substrate composition suitable for use as a carrier for active chemical agents. The composition includes one or more mineral components having a bulk density greater than about 70 pounds per cubic foot. The composition also contains about one or more light weight additives and one or more water soluble binders. The resulting manufactured granular substrate has a bulk density of less than about 55 pounds per cubic foot with a size guide number of about 75 to about 300.

Abstract: A method and apparatus for recovering calcium sulfate di-hydrate (gypsum) from a precipitation reaction between cement kiln dust and commercial, spent or waste grade sulfuric acid solution. The gypsum recovered from this process acts as a necessary functional additive for use in the production of hydraulic Portland cement. The invention advantageously provides for a method of producing a fertilizer as a byproduct of the gypsum production process. The invention also provides a method of producing Portland cement using the gypsum derived from the cement kiln dust.

Abstract: The invention provides a set gypsum-containing product having increased resistance to permanent deformation and a method for preparing it comprising forming a mixture of a calcium sulfate material, water, and an appropriate amount of one or more enhancing materials chosen from condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units. The mixture is then maintained under conditions sufficient for the calcium sulfate material to form a set gypsum material.

Abstract: The invention concerns a composition in dry state for mortar or concrete, comprising a cement and an antishrinkage agent. The invention is characterized in that the antishrinkage agent consist of a calcium sulphate, particularly an anhydrous calcium sulphate, associated with at least a glycol ether.

Abstract: An activated aluminosilicate binder containing aluminosilicates, calcium sulphate and an activator containing alkali metal salts is disclosed. The aluminosilicates are selected from a group consisting of blast furnace slag, clay, marl and industrial by-products, such as fly ash, and has an Al2O3 content greater than 5% by weight. Blast furnace slag is present in an amount less than 35% by weight, and cement kiln dust, in an amount of from 1 to 20% by weight, is added to the mixture as an activator.

Abstract: Emulsions are provided which are useful in imparting water resistance to gypsum products. In one embodiment, the emulsions comprise a plurality of waxes, at least one saponified wax, a complexed starch, a polymerized alkyl phenol, and a small amount of a co-surfactant. In another embodiment, the emulsions comprise a single wax, a balanced dual surfactant system, a complexed starch and a polymerized alkyl phenol. Emulsions of this embodiment may be added to hot, even boiling, water without the emulsion separating or curdling. The emulsions of the present invention are stable for extended periods of time when stored at room temperature and do not require the addition of a bactericide. The emulsions of the present invention are pourable liquids at room temperature.

Abstract: A method of preparation and use of lightweight, high-strength gypsum wallboard, as well as a core composition suitable for use therein, are disclosed. The core composition includes a slurry of calcium sulfate hemihydrate (stucco), water, acid-modified starch, and a starch cross-linking agent, having a pH of about 9 to about 11. The composition and method provide a wallboard having a lower density than conventional wallboard, and with equivalent or better strength characteristics than conventional wallboard.

Abstract: The present invention describes an improved building material composition, useful for example as a fire door core and to improved methods of making this composition. The building material of the present invention consists essentially of expanded perlite, a fireproof binder, clay or vermiculite, and optionally diatomaceous earth, one or more viscosity-enhancing components, reinforcement fibers, and a plasticizer or mixtures thereof. The method of making this improved composition is a semi-continuous batch press method wherein at least the expanded perlite, fireproof binder, and clay or vermiculite are mixed; the mixture compressed in a mold, and the compressed mixture dried.

Abstract: The invention relates to a hydrophobicizing agent for gypsum-plaster-bound construction materials comprising a substrate based on pulverulent organic or inorganic solids with a BET surface area >5 g/m2 and comprising one or more organopolysiloxanes having Si-bonded hydrogen (organohydropolysiloxanes) built up from units of the general formula HaSiR1bO(4-a-b)/2, where the radicals R1 are identical or different monovalent hydrocarbon or hydrocarbonoxy radicals having from one to 15 carbon atoms, or are hydroxyl groups, with the proviso that at least one Si-bonded hydrogen atom per molecule is present, and a takes values from 0 to 3, and b takes values from 0 to 3.

Abstract: A method and apparatus for recovering gypsum from spent cement kiln dust for reuse within a cement making process as a filler for use in the production of Portland cement. The invention advantageously provides for a method of producing a fertilizer as a byproduct of the gypsum production process. The invention also provides a method of producing Portland cement using the gypsum derived from the cement kiln dust.

Abstract: The aqueous suspension contains hydrated n calcium sulfate (CaSO4 nH2O), the value of n ranging from 0 to 2 (0<n<2) and an additive. The method for preparing said aqueous suspension involves the following steps: a) mixing the calcium sulfate and at least one of said additives with water and b) homogenizing the mixture under strong agitation. The method for preparing the paper includes adding said aqueous suspension to the cellulose fiber suspension.

Abstract: A gypsum composition suitable for use in the manufacture of construction materials is provided. The gypsum composition includes gypsum, water, and a dispersant formulation comprising an acrylic/polyether comb-branched copolymer. A method of making a gypsum composition is also provided. The method includes mixing together, in any combination, gypsum, water, and a dispersant formulation comprising an acrylic/polyether comb-branched copolymer. A wallboard is provided including two sheets of board paper, and a gypsum core between the sheets of board paper.

Abstract: Fluorgyp is converted to calcium sulfate by reacting sulfuric acid in the fluorgyp with calcium carbonate having a small particle size. The resulting product is useful as a set retarding agent for cement.