What is the difference between the types of fly ashes?
The Canadian Standards Association (CSA) as per its Standard A-3000 (Cementitious Materials Compendium), designates fly ashes as Type F, CI or CH based on the calcium oxide (CaO) content of the fly ash. Type F has a CaO content of less than 8%, Type CI between 8% and 20%, and Type CH greater than 20%. Concrete made with Type CI fly ash may have a slightly earlier setting time and somewhat higher early strength than concrete made with Type F fly ash. There have been some studies showing that concretes made with Type F fly ashes having better sulphate resistance. There are documented cases of pros and cons to each. Depending on the individual fly ash, there may be no difference in long-term performance of concretes made with Type CI or Type F ash. Lehigh Cement markets Type CI fly ash in the Lower Mainland, Vancouver Island and parts of the Interior of BC and Type F fly ash in parts of the Interior and Northern BC. Type CH fly ash is not available in BC. The standards (ASTM) used in the
