- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 23 Apr 2018
Bentonite is a naturally-occurring material created by the alteration of volcanic ash in marine environments. It consists mainly of the clay mineral smectite, usually montmorillonite, which occur as layers which are compressed between other rock types.
Bentonite is usually obtaines by quarrying, with a solid extracted form with a typical moisture content of around 30%. This moisture content is reduced to approximately 15% by air and/or forced drying after being crushed. Once this has been done, bentonite is either sieved in a granular form, or milled into powder form.
In civil engineering, bentonite is used as a thixotropic, support and lubricant agent. Typical applications for this agent include the construction of diaphragm walls, foundations, pipe jacking, tunnelling, and so on. Its viscosity and plasticity also make it suitable for use in Portland cement and mortars.
Bentonite’s thixotropic properties mean it forms a highly water-resistant gel which, when mixed with additives, can create a permanent barrier to water flow. This is commonly used in situations where soil particles are too small for cement grouting to be suitable, typically to combat seepage in alluvial soils beneath the foundations of dams or other water-bound structures.
For drilling purposes, bentonite can be used as a mud constituent, to seal borehole walls, remove drill cuttings, and so on.
It can also be used in varnishes and paints to act as a thickening and/or suspension agent.
 Related articles on Designing Buildings Wiki
Featured articles and news
The Chartered Quality Institute explain the pathway to success for organisations implementing management systems.
An introductory article looking at where a duty of care can arise in the construction industry.
House of Lords committee encourages the use of off-site manufacturing in new report.
Computational fluid dynamics (CFD) can go some way to show the impact of new buildings on their surroundings.
The shortlist for the 2018 prize for the UK's best new building is revealed.
Amendment to Bill aims to provide councils with greater powers to increase tax premiums on empty homes.
As the latest summer blockbuster 'Skyscraper' is released, we look at some of the best uses of buildings in film.
Read our introductory article on how to layout a building.
New cross-party report calls for combustible cladding ban to be extended to all high-rise residential buildings.
Dr Nicholas Falk, director of the URBED Trust, explains why metro cities are the future of urbanisation.