Relation between Pozzolanic Reactivity of Fly Ash and its Effect in Controlling Alkali-Silica Reaction
T. Yamamoto and T. Kanazu
Appears on pages(s):
accelerated tests; alkali-silica reactions; fly ash; portland cement; pozzolans
Forty fly ash samples obtained from twenty four different thermal power stations were used in the pozzolanic reactivity test, and twenty four fly ashes, original ashes, and air stream classified ones from a single boiler were used in the ASR (Alkali-Silica Reaction) controlling tests. The present work evaluates the pozzolanic reactivity of fly ash by estimating consumption ratio of Ca2+ in the cement and fly ash mixed suspension while considering interactions of other alkali ions released from the cement particle. The index derived from the acceleration test was named as Assessed Pozzolanic-reactivity Index (API), estimating the consumed Ca2+ ratio in the suspension. There was a linear correlation between the API and activity indices obtained from mortar tests (JIS A 6201-1999). On the other hand, the API also showed a linear correlation with expansion ratio, the control effect of fly ash on ASR, obtained from mortar tests (ASTM C 441). The API can stand for the ASR-controlling efficiency. The pozzolanic reactivity of fly ash significantly influences the control effect on ASR, the higher the pozzolanic reactivity, the higher the control effect on ASR.