ALKALINITY CHANGE DURING HYDRATION OF THE BLAST-FURNACE SLAG - FLY-ASH COMPOSITES

The alkalinity change of the alkaline activated blast furnace slag alo ne (a dose of 3 wt.% of Na2O) and of the composites containing up to 2 0 wt.% of the fly, ash component is nearly the same and ranges from th e pH value 11.43 after 3 days of hydration to the value of approx. 11. 2 after 42 days of hydration. An increase of the fly ash conte,lt (up to 60 wt.%) decreases the internal pH values approx. by 0.2 at each re spective time of hydration.