This invention provides low dust low density gypsum wallboard products having high total core void volumes, corresponding to low densities in the range of about 10 to 30 pcf. The wallboards have a set gypsum core formed between two substantially parallel cover sheets, the set gypsum core preferably having a total void volume from about 80% to about 92%, and made from a slurry including stucco, pregelatinized starch, and a naphthalenesulfonate dispersant. The combination of the pregelatinized starch and the naphthalenesulfonate dispersant also provides a glue-like effect in binding the set gypsum crystals together. The wallboard formulation, along with small air bubble voids (and water voids) provides dust control during cutting, sawing, routing, snapping, nailing or screwing down, or drilling of the gypsum-containing products. This invention also provides a method of making the low dust low density gypsum products including the introduction of soap foam in an amount sufficient to form a total void volume, including air voids, preferably from about 80% to about 92% in the set gypsum core, corresponding to a set gypsum core density from about 10 pcf to about 30 pcf. The wallboards produced by the method generate significantly less dust during working.

This invention provides low dust low density gypsum wallboard products having high total core void volumes, corresponding to low densities in the range of about 10 to 30 pcf. The wallboards have a set gypsum core formed between two substantially parallel cover sheets, the set gypsum core preferably having a total void volume from about 80% to about 92%, and made from a slurry including stucco, pregelatinized starch, and a naphthalenesulfonate dispersant. The combination of the pregelatinized starch and the naphthalenesulfonate dispersant also provides a glue-like effect in binding the set gypsum crystals together. The wallboard formulation, along with small air bubble voids (and water voids) provides dust control during cutting, sawing, routing, snapping, nailing or screwing down, or drilling of the gypsum-containing products. This invention also provides a method of making the low dust low density gypsum products including the introduction of soap foam in an amount sufficient to form a total void volume, including air voids, preferably from about 80% to about 92% in the set gypsum core, corresponding to a set gypsum core density from about 10 pcf to about 30 pcf. The wallboards produced by the method generate significantly less dust during working.

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.

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.

An object is to provide an inorganic board and a method for manufacturing the same that are suited to achieving high waterproofness.

A manufacturing method of the present invention includes first to sixth steps. The first step involves depositing a raw material on a receiving plate B1 to form a first layer L1. The second step involves pressing a first portion Ma and a second portion Mb of a raw material mat M including the first layer L1 toward the receiving plate B1 to compress the first portion Ma and the second portion Mb. The first portion Ma and the second portion Mb are one end portion and the other end portion, respectively, of the raw material mat M in a first direction D1. The third step involves depositing a raw material on the first layer L1 to form a second layer L2. The fourth step involves planarizing an exposed surface of the second layer L2. The fifth step involves curing the raw material mat M pressed between the receiving plate B1 and a pressing plate B2 to form a cured plate M′ from raw material mat M. The sixth step involves processing the first portion Ma and the second portion Mb into a first back-side joint part P1 and a first front-side joint part P2, respectively. An inorganic board X1 according to the present invention includes the first back-side joint part P1 and the first front-side joint part P2 that are high-density parts.

An object is to provide an inorganic board and a method for manufacturing the same that are suited to achieving high waterproofness.

A manufacturing method of the present invention includes first to sixth steps. The first step involves depositing a raw material on a receiving plate B1 to form a first layer L1. The second step involves pressing a first portion Ma and a second portion Mb of a raw material mat M including the first layer L1 toward the receiving plate B1 to compress the first portion Ma and the second portion Mb. The first portion Ma and the second portion Mb are one end portion and the other end portion, respectively, of the raw material mat M in a first direction D1. The third step involves depositing a raw material on the first layer L1 to form a second layer L2. The fourth step involves planarizing an exposed surface of the second layer L2. The fifth step involves curing the raw material mat M pressed between the receiving plate B1 and a pressing plate B2 to form a cured plate M′ from raw material mat M. The sixth step involves processing the first portion Ma and the second portion Mb into a first back-side joint part P1 and a first front-side joint part P2, respectively. An inorganic board X1 according to the present invention includes the first back-side joint part P1 and the first front-side joint part P2 that are high-density parts.

The invention is directed to kits, compositions, tools and methods comprising a cyclic industrial process to form biocement. In particular, the invention is directed to materials and methods for decomposing calcium carbonate into calcium oxide and carbon dioxide at an elevated temperature, reacting calcium oxide with ammonium chloride to form calcium chloride, water, and ammonia gas; and reacting ammonia gas and carbon dioxide at high pressure to form urea and water, which are then utilized to form biocement. This cyclic process can be achieved by combining industrial processes with the resulting product as biocement. The process may involve retention of calcium carbonate currently utilized in the manufacture of Portland Cement.

The invention is directed to kits, compositions, tools and methods comprising a cyclic industrial process to form biocement. In particular, the invention is directed to materials and methods for decomposing calcium carbonate into calcium oxide and carbon dioxide at an elevated temperature, reacting calcium oxide with ammonium chloride to form calcium chloride, water, and ammonia gas; and reacting ammonia gas and carbon dioxide at high pressure to form urea and water, which are then utilized to form biocement. This cyclic process can be achieved by combining industrial processes with the resulting product as biocement. The process may involve retention of calcium carbonate currently utilized in the manufacture of Portland Cement.

A composition for addition to a ceiling tile, flooring product, or other construction product may include microfibrillated cellulose and optionally an inorganic particulate material. The ceiling tile, flooring product, or other construction product may further include perlite, mineral wool, wood pulp, starch and other additives, where the wood pulp and other inorganic particulate materials are bonded to the microfibrillated cellulose. Methods of manufacturing the compound are also disclosed.

A composition for addition to a ceiling tile, flooring product, or other construction product may include microfibrillated cellulose and optionally an inorganic particulate material. The ceiling tile, flooring product, or other construction product may further include perlite, mineral wool, wood pulp, starch and other additives, where the wood pulp and other inorganic particulate materials are bonded to the microfibrillated cellulose. Methods of manufacturing the compound are also disclosed.