INFLUENCE OF SIZE FRACTION OF BONDED ASH ON ITS POZZOLANIC ACTIVITY

The paper examines the role of different size fractions of ponded ash, characterised in terms of their physical nature and chemical composit ion, on the lime.-reactivity strength of ash-lime-sand mortars. The pa per also presents SEM and MIP characterisation of different size fract ions. The results of the investigation show the strong influence of th e fine particles on their physical properties and Lime-reactivity stre ngth of mortars. Ponded ash contains both reactive, small particles an d non-reactive or poorly reactive large particles, due to which it los es its overall pozzolanicity. Its use as a pozzolan in cement concrete will only be possible if the non-reactive large sized particles are s eparated from it. The paper concludes that the practice of wet disposa l of fly ash adopted mostly in India is detrimental to the pozzolanic activity of the ash. (C) 1998 Elsevier Science Ltd.