- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 09 Jul 2018
Chert is a type of fine-grained and silica-rich sedimentary rock. It often contains microfossils and/or macrofossils, and can be found in a great variety of colours. It is often confused with flint which is a particular type of chert.
Chert occurs in geology as nodules, concretionary masses and layered deposits, and is characterised by its hardness and conchoidal fractures that create sharp edges. It was these properties that meant chert was used in early human civilisations for creating tools and weapons.
Chert is often used as an aggregate and as a material for road surfacing. It is particularly suited to road surfacing as rainwater firms and compacts it rather than making it 'muddy' like some other fill materials.
However, there can be problems when is used as an aggregate in concrete, such as the development of surface pop-outs as a result of freezing and thawing. This is due to the high porosity of weathered chert. In addition, some kinds of chert can undergo an alkali-silica reaction (ASR) when they come into contact with high-alkali cement which can lead to cracking or expansion.
 Find out more
 Related articles on Designing Buildings Wiki
Featured articles and news
Getting organised below the surface.
Securing suitable water systems.
Love them or hate them, they are popping up everywhere.
The initiative to enhance the environment continues.
Could underused community spaces offer an alternative to working from home?
Keeping workers and workplaces safe in the United States.
A history lesson in geographic information systems.
A low tech, easy to use method of extinguishing small fires.
How can these valued spaces be reused?
Partnership avoids the need for listed building consent.
Connecting building design from inception to completion to operations.
Gregor Harvie predicts interoperability will be construction’s Uber moment.