A gypsum wallboard panel comprises: a gypsum core; and a paper cover sheet disposed on the gypsum core, the paper cover sheet comprising pulp fiber and an uncooked starch in an amount of at least 2% by weight of the pulp fiber.

According to the present invention, there is provided a wet accelerator for use in the manufacture of a gypsum product, said wet accelerator comprising water, particles of calcium sulphate dihydrate and a stabiliser. Additionally, a method of preparing a wet accelerator and a method of producing a gypsum product are described.

Aspects of the invention include a method of producing a cement material comprising step of: first reacting a calcium-bearing starting material with a first acid to produce an aqueous first calcium salt; second reacting the aqueous first calcium salt with a second acid to produce a solid second calcium salt; wherein the second acid is different from the first acid and the second calcium salt is different from the first calcium salt; and thermally treating the second calcium salt to produce a first cement material. Preferably, but not necessarily, during the second reacting step, reaction between the first calcium salt and the second acid regenerates the first acid.

Aspects of the invention include a method of producing a cement material comprising step of: first reacting a calcium-bearing starting material with a first acid to produce an aqueous first calcium salt; second reacting the aqueous first calcium salt with a second acid to produce a solid second calcium salt; wherein the second acid is different from the first acid and the second calcium salt is different from the first calcium salt; and thermally treating the second calcium salt to produce a first cement material. Preferably, but not necessarily, during the second reacting step, reaction between the first calcium salt and the second acid regenerates the first acid.

The present invention relates to the technical field of building materials, in particular to a method for quantitatively regulating the content of periclase in cement. The method comprises: calculating calcination temperature according to formula I; and the formula I is as follows: z=(y−x+3.767)/0.0012 (I), wherein, x represents the content of MgO in the cement clinker, and the unit is wt %; y represents the target content of periclase in the cement, and the unit is wt %; and z represents the calcination temperature, and the unit is ° C. According to the method for quantitatively regulating the content of periclase in cement provided by the present invention, the expected content of periclase in cement can be more accurately obtained, which is more conducive to utilizing the expansion of cement to guide the practical requirements of cement applications in engineering.

The present invention relates to the technical field of building materials, in particular to a method for quantitatively regulating the content of periclase in cement. The method comprises: calculating calcination temperature according to formula I; and the formula I is as follows: z=(y−x+3.767)/0.0012 (I), wherein, x represents the content of MgO in the cement clinker, and the unit is wt %; y represents the target content of periclase in the cement, and the unit is wt %; and z represents the calcination temperature, and the unit is ° C. According to the method for quantitatively regulating the content of periclase in cement provided by the present invention, the expected content of periclase in cement can be more accurately obtained, which is more conducive to utilizing the expansion of cement to guide the practical requirements of cement applications in engineering.

In general, the present invention is directed to a gypsum board comprising a gypsum core and a glass mat facing material including a coating. The coating comprises a resin including an acrylic resin, a siloxane rubber, or a mixture thereof and hydrophobic additive comprising an organosilane. The gypsum board passes at least one of the three air and water barrier tests specified in AC-212 wherein the tests comprise a water penetration barrier test as conducted in accordance with ASTM E331-00, a hydrostatic head test as conducted in accordance with AATCC 127-2008, or an air barrier test as conducted in accordance with ASTM E2357-11.

In general, the present invention is directed to a gypsum board comprising a gypsum core and a glass mat facing material including a coating. The coating comprises a resin including an acrylic resin, a siloxane rubber, or a mixture thereof and hydrophobic additive comprising an organosilane. The gypsum board passes at least one of the three air and water barrier tests specified in AC-212 wherein the tests comprise a water penetration barrier test as conducted in accordance with ASTM E331-00, a hydrostatic head test as conducted in accordance with AATCC 127-2008, or an air barrier test as conducted in accordance with ASTM E2357-11.

Various embodiments disclosed relate to cement activator compositions for treatment of subterranean formations. In various embodiments, the present invention provides a method of treating a subterranean formation including placing in the subterranean formation a liquid cement activator composition including water, an alkali sulfate salt, a polyphosphate salt, and a stabilizer polymer.

Various embodiments disclosed relate to cement activator compositions for treatment of subterranean formations. In various embodiments, the present invention provides a method of treating a subterranean formation including placing in the subterranean formation a liquid cement activator composition including water, an alkali sulfate salt, a polyphosphate salt, and a stabilizer polymer.