What is gypsum plaster a mixture of?

Gypsum plaster is primarily composed of calcined gypsum and lime. Calcined gypsum, also known as gypsum plaster, is a product obtained by heating gypsum to remove water, creating a fine powder. When mixed with lime, this combination helps improve workability and stability while allowing for effective adhesion to surfaces.

The use of calcined gypsum in plaster provides desirable properties such as quick setting times and fire resistance. The addition of lime enhances the strength and flexibility of the plaster, making it suitable for various applications in building construction, particularly in interior walls and ceilings. This mixture forms a smooth finish that is not only aesthetically pleasing but also functional in terms of sound insulation and thermal performance.

In contrast, the other choices mention components that are not typically associated with gypsum plaster. Portland cement and hydrated lime contribute to different types of mortar and concrete but do not create a material that behaves like gypsum plaster. Aggregate and cement are main components of concrete, while blended and plastic cements pertain to cement formulations rather than gypsum plaster. Therefore, the correct answer rests firmly on the characteristics and composition of gypsum plaster as a mixture of calcined gypsum and lime.