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: 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 object of the present invention is to provide a construction and coating composition that effectively utilizes vermiculite as a natural resource and is able to satisfy requirements for humidity control and/or deodorizing as well as an attractive appearance, while also offering superior balance between the amount and rates of moisture absorption and release, in particular. This object is achieved by a composition in which non-expanded vermiculite is blended into a base material so that the blended amount is 5-70 wt % of the total composition (solid portion). In addition, the above construction material can be converted into soil by crushing when it has become a waste construction material.

Abstract: The present invention provides improved early-enhanced strength cement compositions and methods. The cement compositions can be utilized in surface construction projects as well as in the construction of oil, gas and water wells. The improved cement compositions of this invention are basically comprised of a hydraulic cement, water present in an amount sufficient to form a slurry and hydrophobic silica powder.

Abstract: A process for forming crushable, “synthetic” rocks from waste gypsum involves collecting natural and synthetic gypsum waste in the form of flue gas desulfurization (“FGD”). The gypsum waste has a sludge-like consistency and is passed through an extruder where the moisture in the waste gypsum is drawn off and the waste is densified. The removal of moisture is accomplished under vacuum. The densified waste gypsum is extruded through a die to create three-dimensional shapes with preselected aspect ratios.

Abstract: A method for coating the sawed edges of gypsum wallboard to prevent dusting of gypsum particles in clean rooms. The method includes applying a water-dispersible polymers to the sawed edges of gypsum wallboard. The polymer forms a water-insoluble salt through an ion exchange with the calcium found in gypsum wallboard. The result is a tough, tack free, fast-drying coating that substantially reduces the levels of airborne gypsum particles that come from the sawed edges of gypsum wallboards.

Abstract: The invention relates to a process for utilizing waste salt mixtures from HALEX reactions, comprising at least one alkali metal chloride and at least one alkali metal fluoride or bifluoride, and optionally one or more organic compounds, which are depleted by extraction, by contacting the resulting waste salt mixture with concentrated sulfuric acid, removing the resulting hydrogen chloride for the most part by flushing with an inert gas, and reacting the salt-containing sulfuric acid with calcium fluoride to give hydrogen fluoride and alkali metal sulfate-containing calcium sulfate, which can be processed to give a building material binder.

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: A material for use in metal casting comprising an inert refractory filler and a mix of two co-operating binders providing two bonds, the first binder being colloidal silica and the second binder being at least one hydraulic bonding agent.

Abstract: A set gypsum composition and methods for the preparation thereof are disclosed. The set gypsum composition comprises a continuous phase of interlocking set gypsum matrix having an enhanced water voids volume and/or is prepared from a mixture (e.g., slurry) comprising an elevated ratio of water to calcined gypsum. Also disclosed is an article comprising the set gypsum composition.

Abstract: The invention concerns a hydration modifying agent for mortar and concrete comprising a combination of 30 to 80% of calcium sulphate, 3 to 60% of ethylene/propylene oxide copolymer and 0.5 to 6% of an activator for the copolymer. The invention also concerns a Portland dry cement comprising 2 to 10 wt. % of said hydration modifying agent and a method for preparing such a mortar or concrete composition, and a self-spreading concrete topping made from said mortar or concrete composition.

Abstract: The present invention relates to an improvement in cement for use in concrete of high strength and high flowability, mass concrete, shrinkage compensating concrete or concrete of high resistibility which are employed in the field of engineering and architecture or as building material through incremental launching method or wet formation. When the ratio of Al2O3 to Fe2O3 is regulated to a value of 0.05 to 0.62, the strength of concrete of high strength and high flowability can further be improved, and heat of hydration can be prevented, while improving the flowability of cement and maintaining a long-term strength thereof.

Abstract: A wet gypsum accelerator comprising particles of calcium sulfate dihydrate, water, and at least one additive selected from the group consisting of (i) an organic phosphonic compound, (ii) a phosphate-containing compound, or (iii) a mixture of (i) and (ii), is disclosed. Also disclosed are a method of preparing a wet gypsum accelerator, a method of hydrating calcined gypsum to form an interlocking matrix of set gypsum, a set gypsum-containing composition, and a set gypsum-containing product.

Abstract: An additive for accelerating the setting reaction of gypsum products is disclosed. It comprises a gypsum accelerator combined with a bisulfate salt. The gypsum accelerator is calcium sulfate dihydrate. The accelerator may optionally be ground with a sugar, a starch and/or boric acid. A process utilizing this additive combination is also disclosed. The bisulfate salt is most advantageously prewet with a portion of the calcium sulfate hemihydrate feed before being combined with the gypsum accelerator, water and the remaining portion of the calcium sulfate hemihydrate feed in the main mixer.

Abstract: A set gypsum-containing composition is disclosed. In one aspect, the set gypsum-containing composition includes an interlocking matrix of the set gypsum formed from at least calcined gypsum, water, and an enhancing material. The enhancing material can be selected from (i) an organic polyphosphonic compound, or a mixture thereof; (ii) a borate selected from ulexite colemanite, or a mixture thereof; or a mixture of (i) and (ii). In another aspect, the set gypsum-containing composition is treated with an enhancing material which can be selected from (i) an organic phosphonic compound or a mixture thereof; (ii) a borate selected from ulexite, colemanite, or a mixture thereof; (iii) a carboxylic compound or a mixture thereof; or a mixture of (i), (ii) and/or (iii).

Abstract: A composition comprising calcined gypsum, trimetaphosphate ion, and a water-soluble linear polymer formed by the addition reaction of ethylene oxide and/or alkoxy-substituted ethylene oxide with water, having enhanced strength when set and exhibiting high plasticity and workability such that it readily can be applied to a substrate, is disclosed.

Abstract: A constructional finished wallboard is formed of a mixture including 50 to 65 wt. % of dried shirasu, 30 to 40 wt. % of a plaster component, 3 to 10 wt. % of a clay component, 5 to 10 wt. % of shirasu balloons, 0.8 to 2 wt. % of a bond reinforcing component, 0.01 to 3 wt. % of a color pigment, and 1 to 5 wt. % of fibers for plaster. In preparing the wallboard, after preparing the mixture, an appropriate amount of water is added to the mixture to mix together, which is applied onto a substrate. Then, the surface of the mixture on the substrate is finished, followed by drying to thereby form the constructional finished board.

Abstract: A plaster composition for making molds for reproduction by casting is disclosed. Calcium sulfate hemihydrate, potassium sulfate and potassium sodium tartrate are mixed together. The potassium sulfate and potassium sodium tartrate are in a ratio of from about 1:1 to about 10:1. Potassium sodium tartrate is present in an amount of from about 1 to about 10 pounds per ton of dry calcium sulfate hemihydrate, and the total of the potassium sulfate and potassium sodium tartrate is from about 2 to about 35 pounds per ton of calcium sulfate hemihydrate. Methods of making and using molds of this composition are also disclosed.

Abstract: A set gypsum composition and methods for the preparation thereof are disclosed. The set gypsum composition comprises a continuous phase of interlocking set gypsum matrix having an enhanced water voids volume and/or is prepared from a mixture (e.g., slurry) comprising an elevated ratio of water to calcined gypsum. Also disclosed is an article comprising the set gypsum composition.

Abstract: A set accelerator for at least one of accelerating the hydration rate and reducing the set time of an aqueous slurry of calcium sulfate hemihydrate is described. The set accelerator consists of a mixture of ground calcium sulfate dihydrate and zinc sulfate material. Aluminum sulfate material is an optional component of the set accelerator. The set accelerator is particularly useful in accelerating the hydration rates of sprayable plasters. A fluid form of the set accelerator may be made by suspending the solids in water. The fluid form is advantageously used in ready mixed setting type joint compounds.

Abstract: A multipart gypsum casting composition comprising a gypsum composition and a water composition where either the water and/or the gypsum composition contains at least two acids selected from the group consisting of oxalic acid, boric acid, phosphoric acid, citric acid, sodium citric acid, trisodium citric acid, tartaric acid, sulfuric acid, acetic acid, formic acid, malic acid, ascorbic acid and aspartic acid.

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 present invention describes improved fire door cores and improved methods of making these fire door cores. The fire door core of the present invention comprises expanded perlite, a fireproof binder, fire clay or vermiculite, and optionally one or more viscosity-enhancing components, fiberglass, or both. The method of making this improved fire door core is a semi-continuous batch press method wherein the expanded perlite, an fireproof binder, fire clay or vermiculite are mixed; the mixture compressed in a mold, and the compressed mixture dried.

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: Fiberboards are provided containing at least about 65 wt. % calcium sulfate dihydrate derived from hemihydrate or anhydrous gypsum, and at least about 7 wt. % pulped paper fibers. The boards are capable of being formed into structural members having superior mechanical properties and/or fire resistance, including screw-holding capacities in excess of 650 lbs.

Abstract: A filled structure includes a fiber reinforced resinous hollow structure having a tensile strength of at least 30,000 psi, and an inside surface forming a boundary which defines a space. A hard core is provided within the space. The hard core has a density of at least 35 pounds per cubic foot and a compressive strength of at least 1500 psi. The hard core is formed from a mixture of particulate cementitious material and liquid. At least one tendon under stress is provided in the hard core. The tendon is constructed and arranged to exert permanent stress on the hard core.

Abstract: A method of producing a new type of cement, hereafter called Conch-krete. Conch-krete is created by adding sodium carbonate (also known as soda ash, natron, etc.) and one or more minerals from the calcium carbonate group (including aragonite, limestone, calcite, marble, dolomite, etc.) and the addition of water to the mix that will harden into a cement-like material. The combination of sodium carbonate and calcium carbonate can be either layered or in a mixed state. An exothermic reaction starts after the addition of water. The composition of Conch-krete can vary between 20% sodium carbonate and 80% calcium carbonate to 80% sodium carbonate and 20% calcium carbonate. Conch-Icrete can be used in a variety of applications not inclusive of forming bricks, interior architecture, table or counter tops, ornaments, repairing damaged cement products, casting and other applications not mentioned above.

Abstract: A method of reducing the curing time of drywall joint compound, and thereby reducing the time required to finish drywall joints or to repair plaster walls, includes adding a predetermined amount of a drying agent to a conventional ready-mixed drywall joint compound. The drying agent preferably comprises at least one compound selected from the group of compounds consisting of plaster of Paris, calcium carbonate, gypsum, crystallized silicon dioxide (quartz), Portland cement, perlite, lime, hydroxy ethyl ether of cellulose, polyvinyl alcohol, starch, wood fiber, potassium naphthalene sulfon, aluminum sulfate, sodium citrate, ammonium tartrate, hydrolyzed protein, monosodium phosphate, sodium naphthalene sulfonate, potassium sulfate and various trace materials, or mixtures thereof A sufficient amount of water is added to the drying agent to facilitate mixing the drying agent with the drywall joint compound to form a joint compound mixture.

Abstract: A two part joint compound which sets by hydration of calcium sulfate hemihydrate to gypsum and is clay-free. One part includes an in-situ acidic acrylate copolymer thickener (i.e., an associative thickener) with the calcium sulfate hemihydrate, along with a non-calcium bearing phosphate set preventer. The first part contains water, but remains unset for at least 175 days. The second part includes a set initiator compound having a cation with a log K value greater than calcium ions. The second part is mixed with the first part when setting is desired.

Abstract: A composition for accelerating the setting reaction of an aqueous calcined gypsum slurry, and a method of making the same are disclosed. The composition includes a vibratory ball milled mixture of calcium sulfate dihydrate and a surfactant. The composition is prepared by subjecting the mixture to the high-frequency, low-impact grinding action of a vibratory ball mill. The resultant composition has a potency superior to that of conventional gypsum set accelerators.

Abstract: A method of continuously producing a cementitious composition such as joint compound includes pre-mixing at least two dry ingredients and pre-mixing at least two liquid ingredients. The ingredients are provided in a continuous mixing apparatus and at least substantially continuously blended.

Abstract: A method for processing a pulverulent calcium sulphate material in order to obtain a hydraulic binder is described, including combining the following two successive processing steps: (a) heating the pulverulent material in a curing tunnel (1) at a temperature of 220-360° C., under conditions suitable for primarily forming an &agr;-type calcium sulphate, and (b) subjecting the heated material to a thermal quenching step in a cooling apparatus (2), with a cold, dry gas to stabilise the &agr; anhydrite and to prevent its conversion into other crystallographic types. The method provides a novel hydraulic binder with an &agr; anhydrite content of more than 35 wt. %, and with improved strength and behavior in fire resistance properties.

Abstract: A method for the reversible agglomeration of fine particles of plaster of Paris (CaSO4.½H2O) and agglomerates made by the method which comprises agitating the fine particles in the presence of an organic polar liquid preferably nearly dry and having some ability to form hydrogen bonds (especially n-propanol) and then drying off most of the liquid whereby the fine particles spontaneously interlink (possibly by mechanical keying) in a way which allows the interlinks to be disrupted so as to release fine particles when the agglomerates are stirred into water by hand. Also a dry precursor mixture comprising the agglomerates containing conventional auxiliary additives for use in mixing with water to make aqueous compositions for use as filler pastes, casting materials or plaster slurries.

Abstract: An apparatus for continuously calcining gypsum includes a flash calcining impact mill, a feed bin adjacent the impact mill for holding gypsum, and a gypsum feed control mechanism for supplying gypsum from the feed bin to the impact mill at a substantially constant rate. A method for continuously producing calcined gypsum includes the steps of providing a flash calcining impact mill and providing a feed bin adjacent the impact mill, the feed bin containing gypsum to be calcined. A gypsum feed control mechanism is provided for supplying gypsum from the feed bin to the impact mill. Gypsum is supplied from the feed bin to the impact mill at a substantially constant rate, and the impact mill is operated to dry, grind, and calcine the gypsum.

Abstract: Gypsum-based composite boards or shaped bodies can be manufactured from a mixture comprising calcium sulfate dihydrate and water, and optionally reinforcement materials or fillers, and conventional additives, by shaping the mixture to a raw form and hardening the raw form with water at a pressure exceeding the saturation pressure of calcium sulfate dihydrate.

Abstract: A method and a mixture for preparing an ablative material for fire and heat protection is provided. The mixture includes calcium sulfate hemihydrate and a hydrated salt and the ablative material is prepared by adding water to the mixture.

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 process for increasing the water solubility of gypsum in which gypsum is ground to about 5 to 50 mesh U.S. Standard Sieve Size, about 5 to 95 parts by weight of ground gypsum are mixed with about 2 to 25 parts by weight concentrated sulfuric acid having a concentration of about 93 to 98.5% H.sub.2 SO.sub.4, optionally in the presence of about 5 to 20 parts by weight water, and the resulting product is dried at a temperature of about 100-125.degree. C. to form a water-soluble, granular, solid, free-flowing gypsum product having a water solubility increased by about 2- to greater than 350-fold.

Abstract: The invention provides cementitious mixtures, particularly for use as shotcrete binding materials. The resultant shotcrete has characteristics of rapid setting as low as 5 to 10 minutes, high early compressive strength (5 to 25 MPa in two hours curing, 20 to 60 MPa in one day curing), high permanent compressive strength and negligible shrinkage. High aluminous content roasted cement clinkers with gypsum, anhydrite, lime, limestone, bentonite and other additives are used in the mixtures. There are especially suitable for use in shotcrete engineering. The methods of using the improved shotcrete are similar to those of using Portland cement, with significantly decreased rebound at site.

Abstract: A method and system for calcining gypsum to recover gypsum in a form consisting essentially of calcium sulfate anhydrite is disclosed. The method includes the steps of feeding the ground gypsum material into a first kettle and heating the ground gypsum in the first kettle to the first predetermined temperature. The first predetermined temperature is preferably below 400.degree. F. so that the gypsum will still contain a sufficient amount of chemically-combined water so that it will self-fluidize by release of water vapor so that it will flow through the apparatus. The ground gypsum is then overflowed through at least one subsequent stage and heated to a final predetermined temperature to produce an anhydrite product. To produce insoluble calcium anhydrite or dead burn material, the final predetermined temperature is greater than 900.degree. F. and preferably within the range of about 900.degree. F.-1300.degree. F.

Abstract: Fiberboards are provided containing at least about 65 wt. % calcium sulfate dihydrate derived from hemihydrate or anhydrous gypsum, and at least about 7 wt. % pulped paper fibers. The boards are capable of being formed into structural members having superior mechanical properties and/or fire resistance, including screw-holding capacities in excess of 650 lbs.

Abstract: A lightweight gypsum board is provided, including, by dry weight, gypsum as the largest single ingredient, perlite as the second largest single ingredient, and starch as a minor ingredient, in the board. The starch may be pre-cooked prior to mixing, and is dispersed in the core of the board to act as a binder for binding the gypsum to the perlite. Gypsum board made according to the invention is lighter in weight, yet has a comparable nail pull value to conventional wallboard.

Abstract: The invention relates to a self-levelling fluid mortar including calcium sulphate, granulates, lime, water and either a silica and a compound containing alumina or a pozzuolana, and to a screed obtained from said fluid mortar. It also relates to the combined use of lime and either of a silica and of a compound containing alumina or a pozzuolana to increase the mechanical strength and reduce the water sensitivity of a screed.

Abstract: Shell fossil powder is added to a flocculation agent which is mainly composed of gypsum and silicate compound, and the mixture is added to a suspension. The mixing ratio of the flocculation agent and shell fossil powder is 3:1. The flocculation agent functions as a coagulation core A, and the shell fossil powder is able to absorb grains in the suspension as a carrier B and is acquired by the coagulation core A. The carrier B is a grain which is able to effectively utilize Ca.sup.2+ flocculation site of the coagulation core A, which absorbs a great deal of suspending grains, wherein the suspending grains are acquired by the coagulation core A and form a large flock and are quickly settled.

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 method of preparation of 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, and calcium aluminum lignosulfonate and/or aluminum lignosulfonate.

Abstract: Cementitious binders include calcium sulfate beta-hemihydrate, a cement component comprising Portland cement, and either silica fume or rice-husk ash. The silica fume or rice-husk ash component is at least about 92 wt % amorphous silica and has an alumina content of about 0.6 wt % or less.

Abstract: A Portland cement clinker free of C.sub.4 A.sub.3 S having the following proportions of clinker phases, in % by wt.:--C.sub.3 S: 40 to 80--C.sub.4 AF: <20--C.sub.2 S: <30--C.sub.3 A: <20and a SO.sub.3 content from 1.0 to 3.0% by wt., based on the clinker, obtained by burning a mixture of raw materials containing CaO, SiO.sub.2, Al.sub.2 O.sub.3, Fe.sub.2 O.sub.3 and an additive containing SO.sub.3 at temperatures from 1200.degree. to 1350.degree. C. centigrade, the use thereof and a Portland cement.

Abstract: A shrinkage compensating cement exceeding the ASTM standard specification limiting 28 day expansion to 115% of the 7 day expansion. 28 day expansions of 120-200% are contemplated. The expansion takes place over an extended period of time, to better offset the shrinkage occurring as the concrete dries. The development of tensile stresses in the concrete is reduced and also is delayed, allowing more time for the tensile strength of the concrete to increase as the concrete dries. Shrinkage cracking is consequently significantly reduced.

Abstract: A process in which the conventional sulfate components in an aerated concrete mixture, such as gypsum, semihydrate or anhydrite, are replaced at least in part by calcium aluminum sulfates and/or calcium aluminate sulfate hydrates. As a result, agglomeration of the lime, retardation of the lime hydration, and aftergrowth of the cut aerated concrete cakes are reduced or even ruled out. In addition, the number of molds used can be reduced with the process in accordance with the invention, whereby the use of one single mold is achievable.