Method and apparatus for producing a multilayer cementitious product

摘要

Gypsum plasterboard is produced by combining calcium sulphate hemihydrate (stucco) with water to form an aqueous slurry. Uncalcined gypsum having a specific surface area below 0.3 m2/g is added to the slurry and the slurry is discharged onto a support so as to form a sheet of gypsum plasterboard.

主权项

1. A method of preparing an acoustic gypsum wallboard having improved sound blocking properties, the method comprising steps of:
a) combining calcium sulfate hemihydrate with water to form an aqueous slurry; b) adding an inert filler of uncalcined calcium sulfate dihydrate particles of desulphogypsum (DSG) to the slurry within a range of 20% to 25% w:w of the calcium sulfate hemihydrate, the dihydrate particles having a specific surface area of 0.1-0.3 m2/g and a particle size distribution of 0.1-1000 microns; c) discharging the resulting slurry after step b) onto a support; and d) setting the discharged slurry so as to form a sheet of gypsum wallboard having a water gauge reduction with respect to a wallboard containing no uncalcined gypsum, wherein the inert filler provides improved acoustic properties to the wallboard.