API-METHOD, THE PROPOSAL ACCELERATED CHEMICAL ASSESSING METHOD FOR POZZOLANIC REACTIVITY OF FLY ASH

Abstract

Considering the mechanism of pozzolanic reaction of fly ash that occurs in cement matrix is derived from the reaction with Ca²⁺ under high pH condition, the authors proposed an accelerated chemical testing method, API-method, for assessing the pozzolanic reactivity of fly ash. The API-method estimates consumption amount of Ca²⁺ in equally mixed OPC and fly ash suspension under the reacting condition of 80°C for 18-hours. If the content of SiO₂ in fly ash satisfies the regulated amount 45% according to JIS A 6201, API-values showed good linear correlation (R=0.98) to the Activity-Index (AI) of mortar, so the API-method was thought to be an effective assessing method for pozzolanic reactivity of fly ash and AI.