Gypsum is a naturally occurring mineral composed primarily of calcium sulfate dihydrate (CaSO₄·2H₂O). It's a common sedimentary rock and is used in a variety of applications due to its versatility.

Some key uses of gypsum include:

1. Construction: It's used to make drywall (also known as plasterboard or sheetrock), which is a staple in modern building construction for creating walls and ceilings.
2. Agriculture: Gypsum improves soil structure by helping to break up clay soils, allowing for better water infiltration and root growth.
3. Plaster and Cement: It's used in plaster for molding and sculpting, as well as in certain types of cement to control the setting time.
4. Industrial Processes: Gypsum is used in a range of industries, including as a filler in products like paints and as a binding agent in some industrial processes.

It appears as white or gray crystals and can form in various geological environments, including evaporite deposits and hot springs.

Gypsum is a widely used mineral in the construction industry, particularly in the production of plaster, drywall, and cement. Understanding its technical parameters is crucial for ensuring its quality and suitability for specific applications. Here are some key technical parameters of gypsum:

1. Chemical Composition

• Calcium Sulfate Dihydrate (CaSO₄·2H₂O): The primary component of natural gypsum.
• Purity: High-purity gypsum is preferred for industrial applications. Impurities like silica, clay, or organic matter can affect its properties.

2. Physical Properties

• Density: Typically around 2.3 g/cm³ for natural gypsum.
• Specific Gravity: Approximately 2.31.
• Hardness: Gypsum has a Mohs hardness of 2, making it a soft mineral.
• Particle Size: Fineness affects the reactivity and the final properties of gypsum products. It is measured using sieves or laser diffraction techniques.

3. Mechanical Properties

• Compressive Strength: Important for gypsum boards and plasters. Typically ranges from 5 to 10 MPa for plaster.
• Flexural Strength: Indicates the material's resistance to bending. For gypsum boards, it usually ranges from 1.5 to 3 MPa.

4. Thermal Properties

• Thermal Conductivity: Gypsum has low thermal conductivity, making it an effective insulator. Typically around 0.17 W/m·K.
• Thermal Expansion: Low thermal expansion coefficient, typically around 12 x 10⁻⁶ /°C.

5. Hydration Properties

• Setting Time: The time required for gypsum plaster to set and harden. Initial setting time is usually around 25-30 minutes, while the final setting time can be around 45-60 minutes.
• Water Demand: The amount of water required to achieve a workable plaster consistency. This varies depending on the application and desired consistency.

6. Environmental Properties

• Solubility: Gypsum is moderately soluble in water, which can be a factor in certain environmental conditions.
• pH Value: Typically neutral to slightly alkaline, with a pH of around 7 to 8.

7. Fire Resistance

• Gypsum contains water in its crystalline structure, which provides fire resistance. When exposed to heat, the water is released as steam, which helps to slow the spread of fire.

8. Sound Insulation

• Gypsum boards provide good sound insulation properties, which is important for partition walls and ceilings in buildings.

9. Durability

• Resistance to abrasion, moisture, and microbial growth are key considerations for the longevity of gypsum products.

10. Production Process Parameters

• Calcination Temperature: The temperature at which gypsum is heated to remove water and produce plaster. Typically around 150-180°C for plaster production.
• Grinding: The fineness of the ground gypsum affects its reactivity and final product properties.

Understanding these technical parameters helps in selecting the right type of gypsum for specific applications, ensuring optimal performance and durability.