According to the present invention. there is provided a method of manufacturing a plasterboard, the method comprising combining at least one recycled calcium sulphate material and at least one non-recycled calcium sulphate material to form a mixture of particles, combining at least the mixture of particles and water to form a settable slurry, and drying the settable slurry to form a plasterboard, wherein the ratio of the recycled calcium sulphate material to the non-recycled calcium sulphate material in the mixture of particles is at least 1:1, wherein the method further comprises calcining the mixture of particles before the mixture of particles is combined with water to form a settable slurry. A plasterboard is also provided.

Wasted gypsum boards are crushed and calcined to gypsum granular solid, and the gypsum granular solid is mixed with water to form gypsum slurry. Gypsum particles are deposited from the gypsum slurry in a crystallization tank. Heated steam is blown into the gypsum slurry at a height from surface of the gypsum slurry and down to upper of the gypsum slurry to heat the gypsum slurry and to eliminate foam on the gypsum slurry.