A fire-resistant gypsum panel comprises: a gypsum core layer comprising set gypsum and a high temperature sag-resistant material including mineral wool in an amount between 0.2% and 3.0% by weight of gypsum.

This disclosure relates to using polyester films on building boards to enable improved surface coatings. The polyester film is preferably applied to a glass mat via an adhesive to form a laminate. This laminate is then bonded to the exterior surface of a gypsum board. The polyester film is advantageous because it allows for exterior surface coatings to be applied. In one embodiment, an exterior acrylic coating is applied to the polyester film. Boards constructed in accordance with this disclosure allow for exterior finishings to be achieved without the need for excessive finishing materials or steps.

A gypsum slurry modifier device is provided for use with a gypsum mixer outlet boot having at least one tubular outlet leg, and includes a support bracket mountable to the outlet boot; at least one clamp member associated with the support bracket and constructed and arranged for engaging the at least one tubular outlet leg of the outlet boot. Each at least one clamp member is constructed and arranged for exerting a vertical compression force on the associated at least one tubular outlet leg for expanding a slurry outlet flow from the at least one leg laterally beyond an exterior surface of the leg.

An object of the invention is to prevent differences in the flow rate and the specific gravity of a gypsum slurry from being caused between slurry discharge ports, to divide a current of the slurry into streams without a factor of stagnation of the slurry provided at a branch part, and also, to ensure a sufficient distance between the discharge ports. The slurry delivery conduit (10) has a rectilinear tube segment (14), a branch part (15) and branch tube segments (16). A tube-wall joint portion (20) of the branch tube segments configures a counter-flow splitting element (22) in a form of V-letter at the branch part. The slurry is introduced from a mixing area (51) into the rectilinear tube segment, which configures a straight rectilinear fluid passage. The rectilinear tube segment rectifies a flow of the slurry to be an axial or rectilinear current (S), and the axial or rectilinear current is split into branch streams (S1, S2) by the counter-flow splitting element.

Disclosed is a composite gypsum board comprising a set gypsum core disposed between face (e.g., Manila) and back (e.g., Newsline) cover sheets. The set gypsum core is formed from a core slurry comprising stucco, water, and optional additives, such as foaming agent, migrating starch, accelerator, retarder, dispersant, etc. A dense layer formed from a dense layer slurry comprising stucco, water, fiber (e.g., paper fiber), and optionally, strength-enhancing starch, is disposed between the core and the face paper. The dense layer slurry contains a greater concentration of fiber, and optionally, strength-enhancing starch, than the core slurry, but the concentration of one or more other additives (e.g., accelerator, retarder, dispersant, or combinations thereof) is lower or the same in the dense slurry as compared with the core slurry. Also disclosed is a method of making board using one board mixer. In embodiments, paper fiber is added to water to form a suspension. The suspension is introduced, while in a non-laminar state, into the dense slurry. Further disclosed is apparatus, such as an extractor and an additive injection system, which can be a part of a cementitious slurry mixing and dispensing assembly.

Method for producing a cementitious board (1), wherein a first liner (2) with first overlap sections (5) is provided and furnished with at least one layer of at least one slurry comprising a cementitious material (3); a second liner (4) with second overlap sections (8) is provided and arranged such that it contacts the first overlap sections (5) of the first liner (2), wherein the at least one layer of the at least one slurry (3) is arranged between the first liner (2) and the second liner (4); an adhesive foam (6) is provided at least partly on at least one of the first or second overlap sections (5, 8); and the first liner (2) and the second liner (4) are bonded via the adhesive foam (6) in the overlap sections (5, 8).

Disclosed are an organic binder-based coating; a composite gypsum board containing face and back cover sheets, an outside surface of the back cover sheet bearing the coating; and a method of preparing composite board where the back cover sheet contains the coating on its outer surface. The coating is formed from a composition comprising an alkaline silicate, a solid filler, and optionally, a borate. An enhancing layer can also be applied to the back cover sheet.

An uncoated nonwoven fibrous mat having a reduced air porosity is disclosed comprising a first plurality of fibers having a length between about 10 mm and 20 mm and an average diameter between about 9 μm and 15 μm; a second plurality of fibers having a length between about 3 mm and 8 mm and an average diameter between about 5 μm and 8 μm; and a binder composition. The uncoated nonwoven fibrous mat has an air porosity less than about 550 CFM.

A hose (200) is described, the hose comprising a first section (210) comprising a cross sectional area A.sub.χ and a second section (220) comprising a cross section area kj. The first section is in fluid communication with the second section and, in use, the first section is located upstream of the second section. Additionally, Axis at least twice the size of A2. Use of the hose and a method of dispensing slurry are also described.

The present invention is directed to a method of making such gypsum panel. For instance, the method comprises: providing a first facing material; providing a gypsum slurry including calcium sulfate hemihydrate, water, and a silicon containing compound onto the first facing material; providing a second facing material onto the gypsum slurry to form a continuous gypsum sheet; allowing the calcium sulfate hemihydrate to hydrate to form calcium sulfate dihydrate; cutting the continuous gypsum sheet to form a gypsum panel; supplying the gypsum panel to a heating or drying device; and providing a gaseous mixture from the heating or drying device to a regenerative thermal oxidizer.