In the article "Mix Design Hints for Fly-ash Concrete," published in July 1963 the statement is made on page 266, "Never use fly ash in concentrations of 10 percent or less in concrete that is susceptible to alkali-aggregate [nowadays know as alkali-silica] reaction, because it may actually increase the rate and amount of the phenomenon. " Since fly ash is generally used to reduce alkali-silica reaction, what is the basis for the limitation given in this quoted statement? This is of interest to us because of the wide variability in the amount of reactive silica found in alluvial deposits in Arizona.
This statement is based on recommendations given in "Admixtures for Concrete," reported by ACI Committee 212, ACI Journal, November 1963. The specific discussion appears on page 1511 . The same article also appears in the AC/ Manual of Concrete Practice, Part I, where the discussion appears on pages 212 256. A similar but not so specific statement appears in Section 6.2.5 of "Guide for Use of Admixtures in Concrete" by ACI Committee 212, which was published in the AC/ Journal, September 1971, pages 646 to 676. The same "Guide" also appears in the AC/ Manual of Concrete Practice, Part I. The original authority for the statement is an early paper by Thomas E. Stanton, "Studies of Use of Pozzolans for Counteracting Excessive Concrete Expansion Resulting from Reaction Between Aggregates and the Alkalies in Cement," published in the Symposium on Use of Materials in Mortars and Concretes, STP99, American Society for Testing and Materials, 1949, pages 178201. Stanton is credited with having discovered the alkali-silica reaction as one cause of disruptive expansion of concrete.