Fly ash is a byproduct from burning coal which makes steam to generate electricity. When burning coal, combustion particles rise out of the combustion chamber with flue gasses. They are captured in filters to prevent them from reaching the atmosphere and collected for disposal or beneficial reuse. These particles are called fly ash.
There are two types of fly ash, Class C and Class F. Class C has self-cementing properties and is used in the production of concrete as a substitute for Portland Cement, and as a chemical stabilizing & modifying agent to dry and/or strengthen poor soils. Class F has very little self-cementing properties, but can be combined with additives such as quicklime, hydrated lime, or cement (portland or hydraulic) to create cementitious compounds for the same purposes.
