Considering the conventional the US standards, Fly ash manufacturers manufacture two types of Fly Ash – Class F fly ash and Class C fly ash.

In Class F dosages used between 15% and 25% by mass of cementations material, while in Class C it is between 15% and 40%.

• Class F is commonly low in calcium content with carbon less than 5% substances. But sometimes carbon content can be as high as 10%.

• Class C fly ash is also expansion resistant against several chemical attacks and has a higher proportion of calcium oxide. This Class C fly ash is naturally composed of high-calcium with carbon content below 2%.