1. Rationale
Although it is generally recognized that Class C fly ash has a high calcium oxide content and Class F fly ash has a low calcium oxide content, in the ASTM specification on fly ash (C618), the only mention of calcium oxide content of fly ash is in Note 3, which states in part, some Class C fly ashes may contain lime contents higher than 10%. The distinction between Class C and Class F fly ash is made solely on the basis of the sum of the oxides, with Class C having a minimum of 50% and Class F having a minimum of 70% of these oxides. There is no limit on the calcium oxide content for either Class F or Class C fly ash. The proposed ballot items will revise Note 3, add an appendix that details the relationship between the sum of the oxides, and will add a reporting section to the standard.
Keywords
fly ash; natural pozzolan; pozzolans; Calcined pozzolans; Cement materials/applications--specifications; Coal fly ash; Concrete admixtures--specifications; Concrete construction materials/applications--specifications; Fly ash and other pozzolans; Portland cement concrete (PCC)--specifications; Pozzolans--specifications;
Citing ASTM Standards
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