Granulometric analysis of fly ashes by laser diffraction

The laser diffraction technique was used to study the granulometry of Spanish fly ashes because it is rapid, precise and reproducible. The equipment employed can carry out granulometric analyses in the dry and wet feeding systems. This Paper reports the results of both feeding systems under various test conditions, to obtain standard analysis conditions for fly ashes irrespective of their fineness. The granulometric results are compared with those obtained with the Alpine pneumatic siever, as sieving is an accepted method in international standards for this type of material. Scanning electron microscopy studies show the effect of previous sonication treatment on the fineness of fly ashes.