What Is Flyash?
Fly ash is a fine grey powder consisting mostly of spherical glassy particles that are produced as a by-product in coal fired power stations. Fly ash has pozzalonic properties, meaning that it reacts with lime to form cementitious compounds. It is commonly known as a supplementary cementitious material.
Fly ash significantly improves concrete performance in different ways and also provides many benefits in cement and non-cement applications. Shown below are some micrographs of fly ash particles, taken using a Scanning Electron Microscope.
Where Flyash Comes From
Fly ash is a by product of power generation in coal fired power stations. Within a power station, coal is fed to a series of mills that pulverise the coal to a very fine powder. This powder is then fed into a boiler which combusts the coal to produce heat, that is then used to produce steam required for power generation. During the coal combustion process, minerals in the coal fuse to form glassy alumino silicate spheres. These spheres remain in suspension within the flue gas from the boiler and are ultimately collected downstream by either electrostatic or mechanical precipitation.
At its various operating sites, Flyash Australia selectively collects fly ash and subject to rigorous testing, further refines these collected materials to produce quality fly ash products meeting the needs of our customers.
The picture below explains the process of producing fly ash at a power station.