Abstract: A method and apparatus to manufacture gypsum board that directs an aqueous gypsum slurry to a second cover sheet, and passes the second cover sheet over a roller spaced above a first cover sheet so that a majority of the aqueous gypsum slurry of falls off the second cover sheet to deposit over the first cover sheet. Another aqueous gypsum slurry of a different density than the deposited slurry is applied over the first cover sheet before and/or after the deposited slurry. A gypsum board having layers of different densities is made by the method and apparatus.

Abstract: A rapid setting, water durable binder composition includes a mixture of: a reactive powder including cement, at about 10-40 wt. % of the reactive powder, ?-stucco at about 30-75 wt. % of the reactive powder, and pozzolanic material at about 5-30 wt. % of the reactive powder; a plasticizer in an amount equal to about 0.05-3 wt. %, preferably 0.1-3 wt. %, of the reactive powder, and water.

Abstract: Embodiments of a system and a method for detecting moisture within a structure can use a cementitious panel including a moisture sensor. The moisture sensor can comprise a moisture-sensing, passive RFID tag. A reader can be used to periodically interrogate the RFID moisture-sensing tag to determine whether the RFID moisture-sensing tag has been subjected to moisture. Systems and methods for detecting moisture within a structure can use at least one such cementitious panel in a structural assembly, such as a roof assembly, for example, to help detect a leak in the roof assembly through periodic monitoring of the installed cementitious panel(s).

Abstract: Disclosed is a foam modifier, e.g., useful for gypsum or cement slurries. The foam modifier comprises a fatty alcohol that is added to a gypsum or cement slurry that includes foaming agent, such as an alkyl sulfate surfactant. The fatty alcohol can be a C6-C16 fatty alcohol in some embodiments. The use of such a foam modifier can be used, for example, to stabilize the foam, reduce waste of foaming agent, improve void size control in the final product, and improve the gypsum board manufacturing process.

Abstract: An acoustic isolation mat is provided for placement between a subfloor and a finished floor. The acoustic isolation mat has a first layer placed directly upon the subfloor that includes a fiberglass-containing acoustic insulation, a second layer placed directly upon the first layer that includes an entangled polymer, and a third layer placed directly upon the second layer and below the finished floor that has a sheet of fibrous material.

Abstract: An impact resistant exterior sheathing gypsum building panel with an integrated impact resistant woven mesh which protects against impact from projectiles such as those conveyed by hurricane force winds is provided. Methods for manufacturing these exterior sheathing gypsum building panels with an integrated impact resistant woven mesh are also provided. An exterior sheathing system employing the exterior sheathing cementitious building panel is provided.

Abstract: Disclosed is a composite gypsum board comprising a board core and a concentrated layer of substantial thickness (e.g., at least about 0.02 inches). The concentrated layer includes a higher weight percentage of an enhancing additive than the hoard core. The board core has a thickness greater than the thickness of the concentrated layer and forms the bulk of the board volume. The concentrated layer has a higher density (e.g., at least about 1.1 times greater) than the density of the board core. Also disclosed is a method of preparing a composite gypsum board.

Abstract: A gasket for installation in a gap defined by adjacent modular construction units, each having a support frame. The gasket includes at least one layer of structural cement panel; and at least one layer of mineral wool, and the at least one layer of said panel and mineral wool has at least one plate recess configured for accommodating a support plate. A modular building construction is provided, including a plurality of modular units, each unit having a steel frame. Four adjacent units of the plurality form an intersection, and support plates are fastened at upper surfaces of corners formed by each frame. The gasket is disposed in a gap defined at the intersection, the gasket having four plate recesses for accommodating the support plates. In still another embodiment, a method of constructing a building made of modular units including the gasket.

Abstract: Embodiments of a system and a method for evaluating a mat-faced cementitious board specimen can be used to determine a bond strength value for the specimen. A moving assembly is configured to move a pair of non-contact ultrasonic transducers over an X-Y plane relative to the specimen supported in a support fixture such that the specimen is interposed between the transducers. A controller is configured to use ultrasonic signals from the transducers to determine the bond strength for at least one facer of a mat-faced cementitious board specimen. Transducer arrays can be outfitted downstream of the kiln, for example, to provide a system and a method for continuously measuring the bond strength of mat-faced cementitious board during the continuous manufacture thereof.

Abstract: A joint compound including calcium sulfate hemihydrate and/or at least one filler, wherein a total amount of the at least one filler and/or calcium sulfate hemihydrate is at least about 50 wt % of the joint compound on a dry (water-free) basis, preferably the filler comprises calcium carbonate, calcium sulfate dihydrate, or calcium sulfate anhydrite, or a mixture thereof; binder at up to about 15 wt % of the joint compound on a dry basis; polymer thickener at up to about 3 wt % of the joint compound on a dry basis; plasticizer dedusting agent at about 0.01 to about 3 wt % of the joint compound on a dry (water free) basis; and an additive up to about 10 wt % of the joint compound on a dry basis.

Abstract: A gypsum wallboard having a core with a central core layer and one or more densified layers is disclosed. At least one densified layer contains salt absorbent particles of zeolite and/or hydrotalcite to improve adhesion of the gypsum core to a cover sheet. Also, methods of making the gypsum wallboard and a wall system for employing the gypsum wallboard are disclosed.

Abstract: Disclosed are a composite gypsum board and a method of preparing composite gypsum board. The board contains set gypsum layers sandwiched between two cover sheets. The set gypsum layers are formed from at least stucco and water. The set gypsum layers include a board core and one or more skim coat layers. The set gypsum core makes up a substantial thickness (e.g., at least about 90%, at least about 92%, at least about 95%, or at least about 97%) of the total thickness of all the gypsum layers. A first skim coat layer is included on one side of the core, facing a first (face) cover sheet. A second skim coat layer is included on the other side of the core, facing a second (back) cover sheet. At least the second skim layer is formed from a slurry that contains starch. The stucco material generally includes a high salt impurity content, for example, when the stucco is calcined from certain sources of low-quality synthetic gypsum. For example, in some embodiments, the salts are chloride salts, e.g.

Abstract: A method of making a setting type compound by injecting an activator compound into a plaster compound wherein the activator compound tube is coaxial and within the plaster compound tube, each at the same flowrate, the same pressure and the same viscosity. The cross sectional transverse areas of an annulus containing the plaster compound and the hole in the annulus containing the activator compound are the same.

Abstract: Disclosed are a composite gypsum board and a method of preparing composite gypsum board. The board contains at least one set gypsum layer sandwiched between two cover sheets. The set gypsum layer is formed from at least stucco and water. The stucco material generally includes a high salt impurity content, for example, when the stucco is calcined from certain sources of low-quality synthetic gypsum. For example, in some embodiments, the salts are chloride salts, e.g., sodium chloride (NaCl), potassium chloride (KCl), magnesium chloride (MgCl2), and/or calcium chloride (CaCl2)). At least one of the cover sheets is composed of high absorption paper, which enhances the bond between the set gypsum layer and the cover sheet.

Abstract: This invention provides gypsum wallboards with a unique microstructure where the walls between voids are enhanced in thickness and strength to substantially improve the strength and handling properties of the wallboards. A method of making lightweight gypsum wallboards is also provided.

Abstract: An accelerator for accelerating the rate of hydration of calcined gypsum is disclosed. The accelerator comprises calcium sulfate dihydrate particles and a starch. The starch has a cold water solubility of at least about 25% (e.g., at least about 35%) and a viscosity of about 25 Brabender Units (BU) or less when the starch is in a 30% aqueous slurry at 92° C. Also disclosed are a method of preparing an accelerator, method of hydrating stucco to form set gypsum, slurry, and method of making gypsum board.

Abstract: Disclosed are a composite gypsum board and a method of preparing composite gypsum board. The board contains a set gypsum core sandwiched between two cover sheets. The core is formed from a slurry containing stucco, water, and optional ingredients such as foaming agent, accelerator, retarder, polyphosphate, starch, and dispersant, and core intumescent material. The board also contains at least one skim coat and/or hard edges. A face skim coat layer can be included on one side of the core, facing a face cover sheet. A back skim coat layer can be included on the other side of the core, facing a back cover sheet. Hard edges are known in the art and can be formed, e.g., continuously from a stucco slurry for forming the face and/or back skim coats. Preferably, the back skim coat layer and/or the hard edges are formed from a slurry containing stucco, water, skim coat or edge intumescent material (which have the same desired characteristics), and other optional additives as desired.

Abstract: Gypsum boards formed from synthetic gypsum and other gypsum sources having high chloride salt concentrations. Gypsum boards may include a board core including set gypsum between a front cover sheet and a back cover sheet. A total concentration of the chloride anion in the board core ranges from about 150 to 4000 parts by weight (pbw) chloride, typically about 300 to about 3000 pbw, more typically from about 400 to about 2000 pbw, further typically from about 1000 to about 2000 pbw, and further typically from about 600 to about 1000 pbw, per 1,000,000 pbw calcium sulfate dihydrate. A polymer layer contacts an inner surface of the back cover sheet. A densified gypsum layer contacts an inner surface of the front cover sheet. Methods of making the gypsum board, and a wall system for employing the gypsum boards, are also provided.

Abstract: A pallet centering device includes a frame upon which is mounted a plurality of conveyor rollers, the conveyor rollers mounted transverse to a direction of pallet travel. A first pallet pusher unit and a second pallet pusher unit are associated with respective sides of the support frame, both for reciprocal movement transverse to the direction of pallet travel. The first and second pallet pusher units each have pallet pusher members configured for engaging respective sides of a pallet. At least one transverse U-channel rail is mounted to the support frame beneath the conveyor rollers and defining a channel track. Each first and second pallet pusher unit has at least one depending bearing mount aligned with the channel track and provided with a bearing rotatably engaging the channel track. A drive assembly moves the first and second pallet pusher units reciprocally for centering the pallet located on the conveyor rollers.

Abstract: Disclosed is an acid-modified flour and a method of making the acid-modified flour. The acid-modified flour is desirably prepared using a dry milling process. A starting flour is combined with a strong acid to form a mixture. The mixture is heated. A neutralizer is added to increase the pH of the mixture. If desired, the mixture can be dried and any agglomerates can be removed. The acid-modified flour can be used as a binder in a slurry for preparing one or more gypsum layers in a gypsum board.