The present invention relates to a method for producing a gypsum-containing foamed prefabricated building material and to a gypsum-containing foamed prefabricated building material.

The present invention relates to a method for producing a gypsum-containing foamed prefabricated building material and to a gypsum-containing foamed prefabricated building material.

A slurry for manufacturing gypsum board comprises calcined gypsum, water, a foaming agent, and a coalescing agent. The foaming agent imparts a plurality of bubbles in the slurry. Typically, a foam is pre-generated with the foaming agent and the foam is used to form the slurry such that the foam imparts the plurality of bubbles in the slurry. The coalescing agent coalesces the plurality of bubbles imparted by the foam. Typically, the coalescing agent coalesces a plurality of small and partially joined bubbles imparted by the foam to create larger and more discrete bubbles. A gypsum board and method of forming the slurry and the gypsum board are also disclosed. The gypsum board comprises a gypsum layer formed from the slurry. The gypsum layer defines a plurality of bubbles dispersed therein, which are imparted by the foam and coalescing agent of the slurry.

A slurry for manufacturing gypsum board comprises calcined gypsum, water, a foaming agent, and a coalescing agent. The foaming agent imparts a plurality of bubbles in the slurry. Typically, a foam is pre-generated with the foaming agent and the foam is used to form the slurry such that the foam imparts the plurality of bubbles in the slurry. The coalescing agent coalesces the plurality of bubbles imparted by the foam. Typically, the coalescing agent coalesces a plurality of small and partially joined bubbles imparted by the foam to create larger and more discrete bubbles. A gypsum board and method of forming the slurry and the gypsum board are also disclosed. The gypsum board comprises a gypsum layer formed from the slurry. The gypsum layer defines a plurality of bubbles dispersed therein, which are imparted by the foam and coalescing agent of the slurry.

Disclosed is a surfactant composition and its use in the production of a gypsum product. Also disclosed is a method of producing gypsum plasterboard, as well as gypsum plasterboard that is formed from foamed slurry comprising the surfactant composition. The surfactant composition comprises from 60 to 99 wt. % by total surfactant weight of an alkyl sulphate component having the structure: R.sup.1OSO.sub.3.sup.+M.sup.1, in which R.sup.1 is an alkyl having from 9 to 11 carbon atoms and M.sup.1 is a cation. The surfactant composition also comprises from 1 to 40 wt. % by total surfactant weight of an alkyl ether sulphate component having the structure: R.sup.2(OCH.sub.2CH.sub.2).sub.yOSO.sub.3.sup.+M.sup.2, in which R.sup.2 is an alkyl having from 8 to 10 carbon atoms, y has an average value of 0.1 to 5 and M.sup.2 is a cation.

A gypsum board according to the invention comprises calcium sulphate dihydrate; Tartaric acid in an amount in the range of 0.01 to 0.1% w based on the weight of calcium sulphate hemihydrate; A fluidizer in an amount of 1.0 to 10.0 kg/m.sup.3; Starch in an amount of 3.0 to 12.0 kg/m.sup.3.

A gypsum board according to the invention comprises calcium sulphate dihydrate; Tartaric acid in an amount in the range of 0.01 to 0.1% w based on the weight of calcium sulphate hemihydrate; A fluidizer in an amount of 1.0 to 10.0 kg/m.sup.3; Starch in an amount of 3.0 to 12.0 kg/m.sup.3.

An ultra-light, pourable, self-drying cementitious product with improved density control and ultra-low water demand is provided. Compositions and methods for making the products are provided as well, including compositions and methods with ultra-low water demand.

In some embodiments, a method may include preparing building forms including at least some cementitious materials. The method for preparing forms may include mixing substantially dry cementitious material particles with closed cell foam particles to form a substantially dry composition. In some embodiment, at least some of the cementitious material particles may adhere to at least some surface deformations on the surface of the closed cell foam particles. In some embodiments, the method may include mixing a second portion of water with the substantially dry composition for a second period of time to form a partially wet composition. In some embodiments, a method may include forming a building form including at least some cementitious materials from the partially wet composition. In some embodiments, the closed cell foam particles may include expanded polystyrene. In some embodiments, a ratio of the water to cementitious material particles may range from 0.20 to 0.40.

A surfactant composition is disclosed comprising branched alkyl sulfate having 8 to 12 carbon atoms; optionally a linear alkyl sulfate having 8 to 12 carbon atoms; and optionally an alkyl ether sulfate having 8 to 13 carbon atoms. A gypsum slurry or gypsum board core is disclosed comprising gypsum, water, and a surfactant composition as described above. The foam voids in the core have a greater median diameter than foam voids made with corresponding linear alkyl sulfate. A method of controlling the median foam void diameter in a gypsum board is disclosed. A first foam water composition is provided comprising a linear alkyl sulfate surfactant. A second foam water composition is also provided comprising a branched alkyl sulfate surfactant. The proportions of the first and second foam water compositions employed in a gypsum composition are selected, or if desired changed, to provide the desired median foam void diameter.