Fly Ash (Class F ASTM 618)
Fly ash is a byproduct of coal combustion that has pozzolanic properties and can be recycled and used as a supplementary cementitious material. When used as a replacement for portland cement in concrete, fly ash reduces concrete’s shrinkage and permeability. In addition, fly ash improves workability, durability, resistance to sulfate attack and lowers the heat of hydration.
There are two types of fly ash. Class F is created by burning harder, older anthracite and bituminous coal and can be used as a replacement for up to 25 percent of portland cement. In contrast, Class C fly ash is produced by burning younger lignite and subbituminous coal and can be used as a replacement for up to 40 percent of portland cement. For more information on which class of fly ash would meet your project’s specifications, reach out to one of our sales representatives.