Q.: We are interested in any articles concerning the design and use of concrete mixes made with fly ash.

A.: A good 6-page article on the subject is "Mix Design Hints for Flyash Concrete," which appeared in the July 1969 issue of Concrete Construction, page 263. A more complete discussion may be found in the 9-page original paper on the subject, "Proportioning Concrete Mixes Using Fly Ash," by C. E. Lovewell and George W. Washa, Journal of the American Concrete Institute, June 1958, page 1093.

One common mistake in proportioning fly ash mixes is to modify a standard mix by simply replacing some of the portland cement with an equal weight of fly ash. Normally the cement should be replaced with a somewhat larger amount of fly ash. Then the amount of fine aggregate may have to be decreased slightly to prevent stickiness.