Title: Characteristics of Low-Lime Fly Ashes Significant to Their Use in Concrete
Author(s): Ravindra K. Dhir, Frederick H. Hubbard,
John G. L. Munday, and M. Roderick Jones
Publication: Symposium Paper
Appears on pages(s): 693-722
Keywords: cement content; chemical analysis; concretes; fineness;
fly ash; mechanical properties; physical properties; water content;
The results of studies undertaken into the compositional and physical characteristics of a wide spectrum of UK fly ashes, and some from overseas, are examined in conjunction with data available from the literature. No direct relationship was found to exist between the compositional nature of a fly ash and its behaviour in concrete. The single most significant physical parameter characterising ash is shown to be fineness (as measured by 45 um sieve retention) and is used in developing two schemes classifying (a) the water-reducing and (b) the cement-saving abilities of an ash, which give a simple measure of ash suitability for use in concrete. It is demonstrated that for a correctly designed concrete, the grade of ash does not significantly affect its engineering properties, but only the cement savings that can be achieved.