Gypsum is a soft sulfate naturally occurring, white powdered mineral composed of calcium sulfate di-hydrate with the chemical formula CaSO. 4·2H2O. It is widely mined and is used as a fertilizer and main constituent in many forms of plaster, blackboard/sidewalk chalk, and drywall.
It is a raw material for the manufacture of ammonium sulfate and sulfuric acid.
Here we will learn about gypsum, types of gypsum & much more.
Introduction to Gypsum:
The word gypsum is derived from a Greek word meaning ‘to cook’ known as a burnt or calcined mineral.
Gypsum is extensively used as a construction material; it contains 70% of CaSO4, 2H20 can be used for building construction.
Chemically, gypsum is a sulfate of calcium with two molecules of water i.e. CaSO4, 2H20.
It is a crystalline substance that is very little soluble in water and soluble in dilute hydrochloric acid, but it is insoluble in sulfuric acid.
It contains 79.1% calcium sulfate and 20.9% water.
Types of Gypsum Products:
1. Gypsum plaster:
It is the white cementing materials formed by partial or fully dehydration of the mineral mixed with particular diluent or hardener.
When applied in a plastic state, it set and hardened by chemical recombination with water.
2. Gypsum fertilizer:
It is one of the earliest forms of fertilizer used in the United States and it has been applied to agricultural soils for over 250 years.
It is a reasonably soluble source of essential plant vitamins, calcium, and sulfur, it might improve general plant growth.
3. Gypsum board:
It is one of many panel products, the common name for a family of sheet products essentially consisting of gypsum.
It includes boards, glass matte panels, abuse-resistant, impact-resistant panels and shaft liner panels.
4. Gypsum powder:
This powder is a natural product made up of calcium, sulfur, oxygen and hydrogen.
It is especially used in constructing materials such as drywall, however it is also useful in agriculture as soil fertilizer and conditioner.
Properties of gypsum:
Gypsum is fire resistant in nature which prevent the possibility of fire outbreaks that ensure life safety.
The resistance against fire is due to the presence of water within the gypsum products.
The plasterboard of 15 mm thickness contains approximately three litres of crystal water.
When the fire approaches the water, it undergoes evaporation, overlapping a protective layer.
This will help prevent the spread of fire and excess material.
The heating of gypsum products causes water crystals to form within the material; this dehydration by heat is known as calcination.
The casing results on combustion-tolerant materials and allows low safe temperatures to be maintained.
Even after the water crystals have cooled completely, the residue behaves like an insulating layer until it separates.
It is considered an excellent fire retardant due to its non-combustible property and may delay fire spread for hours.
Gypsum products are developed to deal with sound insulation properties.
Other methods such as masonry work commonly used in higher thicknesses; plasterboard is specifically designed to prevent noise reduction and redistribution.
The air space between the two solid wall results in excessive acoustic efficiency which prevents noise from being passed.
Instead of a 110 mm thickness masonry wall, we are able to install 75 mm thickness drywall to achieve the same sound efficiency.
The thermal properties are capable of creating very good stability of indoor humidity and temperature.
Gypsum construction such as plasterboard or formwork construction has additional insulation properties.
The use of plasterboard inside the building acts as a vapour barrier & avoids the indoor humidity.
Advantages of Gypsum:
Provides smooth surface:
It is used as a plaster material, if given properly whiteness which is free from scars.
Balance Indoor Atmosphere:
They have a natural ability to balance humidity as well as the indoor climate.
It is environmentally friendly, fire-resistant in nature, extreme thermal and acoustic insulation.
It gives a very good aesthetic view and useful features.
The inclusion of gypsum products within the budget promotes the creativity of architects.
Ease of installation:
Using these products inside the wall construction, we simply want to repair the frame and fill the joints.
The entire process is simple and quick; using this plaster as the final finish minimizes additional painting work.
White finishes give themselves a clear look.
Variety of Gypsum Products:
A large number of its products can be found that satisfy many aesthetic needs.
It also provides adequate technical support.
Disadvantages of Gypsum:
- For the same thickness, gypsum plaster is more expensive than cement plaster.
- Gypsum plaster is undesirable on exterior walls because they are prone to moisture and in areas that are constantly moist such as bathrooms, toilets, wash areas, kitchens, etc.
- Gypsum boards include difficulty in curved surface application and low durability when damage from impact or friction occurs.
Uses of Gypsum:
The uses include architecture, art, ceramics, food essences, pharmaceutical and medical plasterboard and various uses are as follows:
1. Building materials industry:
The largest user of gypsums is the building materials industry, which is used to produce all kinds of building materials and as raw materials for cement and cementing materials.
The production of gypsum partition board, load-bearing inner wallboard, external wall block, wall covering board, ceiling and so on.
2. Model plaster:
Model gypsum can be used in foundry, art, ceramics and other industries.
It can be used to produce sulfuric acid and ammonium sulfate fertilizer.
Anhydrite can adjust soil pH, improve the soil environment, and provide calcium, sulfur and other nutrients for various fertilizers.
4. Food industry:
In terms of food, gypsum can coagulate soybean milk into tofu, and it can also be used as a coagulant in canned tomatoes.
5. Pharmaceutical industry:
Plaster external fixation is still the basic method for clinical treatment of fractures and various orthopedic diseases.
It has the functions of maintaining, fixing and maintaining the special posture of the affected limb, reducing or eliminating the weight-bearing of the affected area, and so on.
6. Fillers for plastics and rubber:
After processing, anhydrite can be used as a filler for plastics and rubber.
The modified anhydrite filler can improve the mechanical strength, heat resistance and dimensional stability of the polymer.
7. Production of calcium sulfate whisker:
Gypsum can be transformed into a calcium sulfate whisker in an aqueous medium under the conditions of high temperature and high pressure.
Calcium sulfate whisker can be used as reinforced filler in resin matrix composites, friction materials, binders and other industries.
Also read: Superplasticizer, Geotextile, Admixture & Fly ash
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate with the chemical formula CaSO₄, 2H2O; it is extensively used in mining, fertilizer and cement manufacturing.