METHOD OF PRODUCING WATER-RESISTANT GYPSUM BUILDING MATERIALS Russian patent published in 2011 - IPC C04B11/30 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing water-resistant gypsum materials. The method of producing water-resistant gypsum building materials involves tempering hydraulic binder containing calcium silicate with an aqueous solution of a strong acid and mixing the obtained product with gypsum binder which is in form of a phosphohemihydrate of calcium sulphate. The strong acid used is sulphuric acid and water is added during said mixing, with the components in the following ratio in wt %: hydraulic binder 30; phosphohemihydrate of calcium sulphate 70; water to water-solid ratio 0.3, where amount of strong acid used is such that content of non-bonded SiO₂ formed during decomposition of silicates is equal to 10-25% of the weight of solid components formed during hardening of the said hydraulic binder.

EFFECT: high strength of water-resistant gypsum building materials.

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