Research on the Dissolving Character of Active Si/Al in Fly Ash Activated by Alkali

This paper investigated the influence of activator concentration, reaction time and fineness of fly ash on the dissolving character of the active Si/Al in fly ash activated by alkali. The results indicated that with the increase of the NaOH solution concentration, the dissolving percentage of active Si/Al in the fly ash went up. The finer the fly ash particles were, the higher dissolving percentage of active Si/Al was obtained. Under strong basic (2M NaOH solution) and boiling condition, the reaction time of active Si/Al dissolving was short and less than 10 minutes. The content of vitreous phase contributed to the content of active components. Active Si existed in the state of Q unit which presented an isolated silicon-oxide tetrahedron in fly ash, and active Al exhibited as Al[OSi](3) and Al[OSi](4) units in 4 coordinate. As the fly ash was activated by alkali, smooth shell of fly ash was gradually corroded by NaOH solution, glass phase was dissolved and crystal phase was exposed to the outside.