Early strength development and hydration of alkali-activated blast furnace slag/fly ash blends Available to Purchase

This study concerns the effect of two types of fly ash and the addition of lime on the strength development and hydration of sodium hydroxide- and sodium silicate-activated slag/fly ash blends which consisted of 50% fly ash and 50% slag by mass. Performance was compared to that of 100% slag cements. When NaOH was used as an activator, the slag replacement with ASTM Type F fly ash did not show a significant effect on either the strength development or hydration; Type C fly ash did not affect the strength development, but affected the hydration process due to the presence of C³A in the fly ash. Both fly ashes had a significant effect on the hydration and strength development when Na²SiO³ was used as an activator. The addition of a small amount of hydrated lime significantly increased the early-age strength but slightly decreased the later-age strength of the activated slag/fly ash blends. Measurement of the heat evolution during hydration indicated that the addition of the hydrated lime had a slight effect on the hydration during the pre-induction period, but accelerated the hydration thereafter.