- Pyrrhotite : Pyrrhotite
Definition : Pyrrhotite
Mineral (iron sulphide) found in the stone (aggregate) used in the composition of concrete. By oxidizing in contact with humidity and oxygen, pyrrhotite:
- produces sulphuric acid;
- increases the volume of the stone;
- attacks the cement paste.
Increasing the volume of the stone can cause the concrete to swell and burst.