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: 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: 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 continuous manufacturing line for preparing gypsum fiberboard is provided. The manufacturing line includes equipment for admixing hydratable gypsum, paper, and a quantity of water to form a substantially homogenous slurry, dewatering apparatus for removing a portion of the excess water from the slurry to produce a substantially continuous wet web, pressing equipment for configuring the wet web with a compression means to form a substantially continuous green board, a cutting station for cutting the substantially continuous green board into individual uncured lengths, and a heating station for curing the individual uncured lengths to form gypsum-dihydrate-containing fiberboards.

Abstract: A door frame having excellent fire-resistance, flexural strength and screw holding properties is fabricated from gypsum fiberboard, specifically a gypsum fiberboard having a density of at least 60 lbs./cu.ft., a flexural strength of at least about 30 lbs. (1/2" thick material), and a screw holding capability of at least about 400 lbs. A preferred gypsum fiberboard material for fabrication of the door frame comprises a composition containing a substantially uniform dispersion of solids including by weight about 65% to 90% set gypsum, about 7% to about 30% pulped paper, up to about 9% binder, and about 0.8% to 2% inorganic fiber. A wood veneer is preferably applied to the visible faces of the gypsum fiberboard door frame members.

Abstract: Fire-resistant structures are provided having at least a 20 minute ASTM E-152 fire test rating. The structures include a core having a gypsum-containing composition and a density of at least about 60 lbs/ft, a flexural strength of at least 30 lbs (1/2 inch thick material), and a screw-holding capacity of at least about 400 lbs. The gypsum-containing composition further contains a substantially uniform distribution of solids including about 65 wt. % to about 90 wt. % set gypsum dihydrate, about 7 wt. % to about 30 wt. % paper fiber, and about 1.5 wt. % to about 35 wt. % of one or more performance boosters selected from inorganic fiber, clay, vermiculate, and binder polymer.

Abstract: Compositions containing nonfibrous calcium sulfate in hemi-hydrate or anhydrous form and fibrous additives, including paper fibers preferably derived from waste newspaper, capable of being formed into an unfaced building material having superior mechanical properties and/or fire resistance.

Abstract: Firedoor constructions manufactured from board compositions containing calcium sulfate in hemi-hydrate or anhydrous form and fibrous additives, including pulped paper fibers preferably derived from waste newspaper, capable of being formed into firedoor members having superior mechanical properties and/or fire resistance.

Abstract: A method for incorporating siloxane into a water-resistant, gypsum-based article is disclosed, comprising, (A) adding said siloxane to water; (B) mixing said siloxane/water mixture with calcined gypsum to form an aqueous slurry; and (C) allowing said slurry to set to form a set gypsum-based, water-resistant article.

Abstract: A fire door core in which the major ingredient is expanded perlite and including, as minor ingredients, set gypsum, set hydraulic cement and an organic binder, and having a density of no greater than about 30 lbs. per cubic foot, and preferably including unexpanded vermiculite, clay, and fibrous reinforcements, and a process for making said fire door core, and also a fire door including said core.