What Is Gypsum Plaster?
Gypsum plaster is made by heating gypsum at low temperatures to drive off water, to produce plaster of Paris a chalky, fast-setting material commonly used for molds and for casts to repair broken bones.
It can be mixed with time to form a fast-drying interior finish plaster known as gauging plaster, according to Bob Campbell, a 17-year plasterer who began work in Scotland.
Lime and gauging plaster, he tells us, aren’t very popular any more. If gypsum is heated at higher temperatures, the resulting product is anhydrous calcium sulfate. This substance is most commonly used to manufacture drywall and drywall compound. It is also used as an interior plaster.
What Is Cement Plaster?
The cement plaster consists of one part of cement to four parts of clean, coarse, and angular river sand by volume the materials are thoroughly mixed in a dry condition before water is added to them.
The mixing of materials is done, or a watertight platform and plaster of one cement bag only are prepared at a time, and this quantity of plaster is consumed within 30 minutes after adding water
Gypsum Plaster Vs Cement Plaster
| Sr.No. | Gypsum Plaster | Cement Plaster |
| 1 | Whereas gypsum plaster can only be used on interior rooms it cannot be used in wet areas like toilet bath kitchen wash area balconies etc. | Cement plaster can be used for plastering both the external walls and the internal walls and ceilings of the building. |
| 2 | Gypsum plaster does not shrink as it undergoes very little expansion and contraction. So there are fewer Shrinkage cracks in gypsum plaster as compared to traditional cement plaster. | Cement plaster has the tendency to shrink, which results in hairline cracks on the plastered surface. |
| 3 | Gypsum plaster is highly resistant to mould and mildew. | Cement plaster is prone to attacks by mould or mildew. |
| 4 | Gypsum plaster doesn’t need any curing saving water and time during construction. | The cement-plastered surface needs curing with water for at least 7 days. Do note that improperly cured walls develop cracks. |
| 5 | Gypsum plaster isn’t resistant to moisture. | Cement plaster is resistant to moisture. |
| 6 | Gypsum plaster, gypsum is used as a binding material instead of cement. Gypsum plaster It is ready to use and does not need sand. | Cement plaster is a homogeneous mixture of Portland cement and sand with water. Sand and cement are mixed at the site in different ratios. |
| 7 | Gypsum plaster is generally 11 mm thick for walls and 8 mm thick for ceiling and finish coat plaster is 2 mm thick. | The thickness of the cement plaster should not be less than 10 mm. For example, for brick walls thickness of plaster is 12 mm to 20 mm. For the interior of the RCC ceiling/ roof, thickness of the plaster is generally 10 to 12 mm. |
| 8 | Gypsum plaster has low thermal conductivity and good thermal properties and ensures energy and power saving. | It has less same thermal conductivity as Gypsum plaster. |
| 9 | Gypsum plaster can prevent shrinkage because it has high tensile and flexural strength. | Cement plaster can develop shrinkage because it has Low tensile hand fractural and strength. |
| 10 | Gypsum is non-combustible and contains a high content of crystal water. In the event of a fire, it acts as a barrier and will protect. | Cement plaster up to 200 to 300 C acts as refractory material and resists fire but later it becomes brittle and breaks and falls and loses bond with the wall. |
| 11 | Gypsum as a binder is used in the manufacture of acoustic tiles and plasters, a contributory factor to the absorption of airborne sounds. | Cement plaster has more or less same acoustics properties. |
| 12 | Due to the nature and structure of gypsum, it exhibits excellent bonding properties hence is applied in a single coat on RCC ceilings, internal bare-brick walls, AAC blocks, and concrete columns. | Cement plaster cannot be applied on the smooth surface. |
| 13 | The setting time of gypsum plaster can be controlled. The time between two successive coats is very small. | The minimum 24-hour interval between coats of interior Portland cement plaster. After a 48-hour period finish coat plaster may be applied to the interior cement base coat. |
| 14 | The percentage of wastage is nominal during application. | The percentage of wastage is higher during application. |
| 15 | The application of gypsum plaster is a time-saving process, thus decreases the project cost. Gypsum plaster is costlier than cement plaster for the same thickness. | The application of cement plaster is a time-consuming process hence increases the project cost. However, per square feet cost of cement plaster is less than gypsum plaster due to the higher cost of gypsum. |
| 16 | After sand cement plaster, POP punning is required for the better and level surface finish. The space looks small and unattractive as it is dark grey in colour. | Gypsum plaster provides a smooth interior finish for ceiling, walls and is an ideal back-ground for good quality paints and wallpaper finishes. The room space looks large and beautiful as gypsum plaster is pure white in colour. |
| 17 | Gypsum plaster keeping is not required we can directly apply the paint. | In the case of cement plaster, we need pop punning on the plastered surface to receive paint. |
| 18 | Whereas is gypsum plaster is a green building product. | Whereas is gypsum plaster is a green building product. |
| 19 | Gypsum plaster is a time-saving process thus decreases the project cost. | Cement plaster is a time-consuming process, hence increases the project cost. |
| 20 | The density of gypsum plaster is less as compared to cement plaster gypsum plaster is light in weight. | The density of cement plaster is higher than gypsum plaster, hence the load on the building increases. |
| 21 | Gypsum plaster is the perfect rust preventive agent and also inhibits corrosion of electric metal, fitting. Pipes etc. | Cement plaster is not a rust inhibitor. |
FAQs on Gypsum Plaster and Cement Plaster
What is Gypsum Plaster?
Gypsum plaster is made by heating gypsum at low temperatures to produce plaster of Paris, a fast-setting material commonly used for molds and casts to repair broken bones. It is also used as a finish plaster for interiors.
What is Cement Plaster?
Cement plaster consists of one part cement to four parts clean, coarse river sand by volume. The materials are thoroughly mixed in dry condition before water is added, and the plaster is prepared in small batches to be used within 30 minutes.
Can Gypsum Plaster be used in wet areas?
No, gypsum plaster is not suitable for wet areas like bathrooms, kitchens, and balconies. It is only used for interior rooms.
Does Gypsum Plaster shrink or crack?
Gypsum plaster undergoes very little expansion and contraction, resulting in fewer shrinkage cracks compared to cement plaster.
Is Gypsum Plaster resistant to mold and mildew?
Yes, gypsum plaster is highly resistant to mold and mildew.
Does Gypsum Plaster require curing?
No, gypsum plaster does not require curing, which saves water and time during construction.
How does Gypsum Plaster perform in terms of moisture resistance?
Gypsum plaster is not resistant to moisture, making it unsuitable for exterior applications or damp environments.
What materials are used in Cement Plaster?
Cement plaster is a mixture of Portland cement and sand with water. The materials are mixed on-site in different ratios depending on the application.
What is the typical thickness of Gypsum Plaster?
Gypsum plaster is generally 11 mm thick for walls and 8 mm thick for ceilings. The finish coat plaster is 2 mm thick.
How does the thermal conductivity of Gypsum Plaster compare to Cement Plaster?
Gypsum plaster has low thermal conductivity and good thermal properties, which helps in energy and power saving. Cement plaster has similar thermal properties but is generally less efficient in thermal insulation.
How does Gypsum Plaster affect fire safety?
Gypsum is non-combustible and contains a high content of crystal water. In the event of a fire, it acts as a barrier and protects the structure.
Can Cement Plaster be applied on smooth surfaces?
No, cement plaster cannot be applied on smooth surfaces without proper preparation.
What is the setting time for Gypsum Plaster?
The setting time of gypsum plaster can be controlled, and the time between two successive coats is minimal.
Is there a difference in wastage between Gypsum Plaster and Cement Plaster?
Yes, the percentage of wastage is nominal during the application of gypsum plaster, while it is higher for cement plaster.
How does the cost and application time of Gypsum Plaster compare to Cement Plaster?
Gypsum plaster is a time-saving process, reducing project costs, though it is costlier per square foot compared to cement plaster. Cement plaster is time-consuming and increases project costs but is cheaper per square foot.
Is additional finishing required for Gypsum Plaster before painting?
No, gypsum plaster provides a smooth finish and does not require additional finishing before painting. In contrast, cement plaster often requires POP punning for a better surface finish.
How does the weight of Gypsum Plaster compare to Cement Plaster?
Gypsum plaster is lighter in weight compared to cement plaster, reducing the load on the building.
Does Gypsum Plaster prevent rusting of metal fittings?
Yes, gypsum plaster acts as a rust preventive agent and inhibits corrosion of electric fittings, pipes, etc. Cement plaster does not offer this advantage.
Can Gypsum Plaster be considered a green building product?
Yes, gypsum plaster is considered a green building product due to its environmental benefits and energy efficiency.
