Activated coal fly ash as improved mineral addition in cement and concrete

A laboratory investigation on the use of coal fly ash (FA) with coarse grain size and high LOI as pozzolanic material for the production of cement mortars was carried out. To that aim the FA was grinded by means of a planetary ball mill until a size distribution similar to silica fume and its LOI was reduced in a triboelectrostatic separator. Some basic properties (i.e., workability, setting times and mechanical strength) of mortars with Portland cement or sand substituted by micronized or beneficiated micronized FA or silica fume were comparatively evaluated. Based on the experimental results, a consistent chemico-mechanical improvement of such FA was achieved, making their use in high strength cement conglomerates profitable.