Gypsum
Gypsum is a soft sulfate mineral with the chemical formula CaSO4·2H2O, also known as calcium sulfate dihydrate. It is comprised of calcium, sulphur bound to oxygen, and water. Natural gypsum is an abundant mineral in sedimentary rocks that has been mined and used for construction and and as a fertilizer since the time of Ancient Egypt.
More recently the term synthetic gypsum is used to describe gypsum that is manufactured or that forms as a by product of other processes, such as flue gas desulphurisation (FGD) gypsum which forms in coal-fired power stations.
Pure gypsum is typically white, although impurities create a wide range of different colours. Gypsum is moderately water soluble but exhibits retrograde solubility, meaning it becomes less soluble at higher temperatures. It is fire resistant and is effective at preventing the passage of sound.
In terms of production, gypsum rock is mined or quarried and then crushed and ground into a fine powder. A process of calcining heats the powder, driving off most of the chemically-combined water. The two other forms of gypsum are called selenite and satin spar.
This base gypsum is used for a wide variety of applications:
- Plaster, plasterboard, wallboard, and so on.
- Blockwork.
- Mortar.
- Blackboard chalk.
[edit] Related articles on Designing Buildings
Featured articles
Check out some of the best features and news from Designing Buildings as well as key stories from around the web.
UKCW Birmingham returns with bold new theme and focus.
New guidance published on competence requirements for self-certification schemes.
Construction Management, 8 July
NEETs crisis drives interest in trades, but apprenticeships barriers remain.
Passive fire protection webinar
MEP services penetration seals.
Where its at podcast (and video) - The role of the Architectural Technologist as an Expert Witness.
More than 200 remarkable buildings added to SAVE’s Buildings at Risk register.
Government scraps pre-application consultation for Nationally Significant Infrastructure Projects.
Historic England and infrastructure
New projects offer opportunities for the historic environment and local communities.
Construction Management, 2 July
Construction deaths halve in two years.
Green Book changes to drive investment in all parts of UK.
Minimum energy efficiency standards (MEES)
CIAT briefing on response to consultations for privately rented non-domestic properties.
Comments
Please note the requirement for ensuring that gypsum products are correctly disposed of, it should not be mixed with biodegradable waste at a standard landfill site. It is possible to recycle the material.