WATER-RESISTANT GYPSUM MATERIAL AND ITS PRODUCTION METHOD

摘要

PURPOSE:To obtain a water-resistant gypsum material useful as a floor covering material or a wall material requiring high strength in a wet state and low water dissolution rate, to provide its production method and to produce efficiently and at a low cost a frame for placing concrete, etc. CONSTITUTION:Gypsum is mixed with an aqueous solution containing 0.1-1% of polyacrylic acid hydrazide to prepare a slurry. The slurry is mixed with a solution of an aldehyde or a polyvalent metal ion, pressurized and dehydrated. Or the slurry is mixed with the solution of an aldehyde or a polyvalent metal ion, pressurized and dehydrated or the slurry is pressurized and dehydrated and immersed in the aldehyde or the solution of a polyvalent metal ion.