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.

A sound damping wallboard and methods of forming a sound damping wallboard are disclosed. The sound damping wallboard comprises a gypsum layer with a gypsum surface having an encasing layer. The encasing layer is partially removed to expose the gypsum surface and form a gypsum surface portion and a first encasing layer portion on the gypsum layer. A sound damping layer is applied to the gypsum layer to cover at least part of the gypsum surface portion and the encasing layer portion.

A sound damping wallboard and methods of forming a sound damping wallboard are disclosed. The sound damping wallboard comprises a gypsum layer with a gypsum surface having an encasing layer. The encasing layer is partially removed to expose the gypsum surface and form a gypsum surface portion and a first encasing layer portion on the gypsum layer. A sound damping layer is applied to the gypsum layer to cover at least part of the gypsum surface portion and the encasing layer portion.

An example plasterboard includes a layer of hardened plaster having a first surface and an opposed second surface, a layer of polymer material having particles of one or more cementitiously-active substances mixed therein, and a liner between the first surface of the layer of hardened plaster and the layer of polymer material. Another example is a method of forming such a plasterboard. The method includes loading an extruder with the polymer material having the particles of one or more cementitiously active substances mixed therein, extruding the polymer material through a die to form the layer of polymer material on a surface of the liner, contacting with a layer of wet plaster material, the liner having the polymer material applied thereon such that the surface of the liner faces away from the wet plaster material, and drying the layer of wet plaster material to form the layer of hardened plaster.

Disclosed is a gypsum board comprising a set gypsum core disposed between two cover sheets. The set gypsum core is formed from a slurry comprising stucco, water, and at least one pregelatinized starch having a viscosity of from about 20 cP to about 300 cP as measured according to the VMA method described herein. The starch is present in an amount of greater than 10% by weight of the stucco. In preferred embodiments, the board has good strength properties even at lower densities, such as about 31 pcf or less. Also disclosed are a related method of making a gypsum wallboard and a slurry.

A building board including a cementitious layer between two fiber mats. At least one fiber mat forms with a polymer film a fiber mat/polymer film laminate. The cementitious layer of the building board contains a reactive water-insoluble polymer which improves binding of the fiber mat/polymer film laminate to the cementitious layer. The building board has a low water absorption and a high level surface finish.

Embodiments of a system and a method for manufacturing a gypsum board can be used to produce a gypsum board having at least one perforated cover sheet via a cover sheet perforator system. The cover sheet perforator system can include a perforator roller is disposed downstream of a forming station along a machine direction, a roller support frame for rotatably supporting the perforator roller such that its rotational axis extends along the cross-machine direction, and a motor arranged with the perforator roller to rotate the perforator roller about the rotational axis. The drive motor can be adapted to rotate the perforator roller with a tangential speed substantially equal to the line speed to produce a series of perforation holes in an upwardly-facing cover sheet as the gypsum board moves past the perforator roller.

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.

An example plasterboard includes a layer of hardened plaster material having a first surface and an opposed second surface and a layer of molded material having a surface that faces away from the layer of hardened plaster material. The surface of the layer of molded material has one or more raised features. The plasterboard also includes a liner between the first surface of the layer of hardened plaster material and the layer of molded material. Other examples include a method of forming such plasterboards and a method for installing such plasterboards.

The tape incudes a water vapor-permeable air and water barrier article and a pressure sensitive adhesive layer. The air and water barrier article includes a fibrous layer having first and second major surfaces and a polymeric layer on a first major surface of the fibrous layer that penetrates into the fibrous layer but leaves at least some fibers exposed on the second major surface. The pressure sensitive adhesive layer is on the polymeric layer of the air and water barrier article. The tape can retain greater than 50 percent by weight of mortar applied according to the Vertical Mortar Receptivity Evaluation. The article includes a substrate, the tape, and a composite layer comprising at least one of gypsum, lime, or cement. The composite layer is at least one of dried or cured on the second major surface of the fibrous layer. Methods of making the article are also described.