Sulfate Resistance of Fly Ash Concretes--The R-Value


  • The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

International Concrete Abstracts Portal


Title: Sulfate Resistance of Fly Ash Concretes--The R-Value

Author(s): Edwin R. Dunstan, Jr.

Publication: Special Publication

Volume: 100


Appears on pages(s): 2027-2040

Keywords: chemical analysis; concrete durability; expansion; fly ash; mortars (material); sodium sulfate; sulfate resistance; tests; General

Date: 4/1/1987

In 1973 the Bureau of Reclamation began research on the use of subbituminous and lignite fly ashes in concrete. By 1978 that research had led to the development of the fly ash R-value as an advance indicator of potential sulfate resistance of concretes containing fly ash. The R-value is calculated from results of a chemical analysis of the fly ash as (percent of CaO - 5)/(percent of Fe2O3). This paper is a review after more than 12 years of sulfate resistance testing. Many of the fly ash concretes in this research have failed in sulfate testing over the last 12 years; however, many of these concretes have not failed and are still under test. These sulfate resistance test results indicate that the R-value remains a good indicator of potential sulfate resistance of fly ash concretes. When concrete contains 15 to 25 percent fly ash with an R-value less than 3.0 the sulfate resistance will be equal or better than a concrete with the same cement and no fly ash.