2012 Volume 23 Issue 1 Pages 1-11
Feature analysis of fly ash (FA) was carried out for five different FA (equivalent to JIS Class II) having varied levels of alkali-silica reaction (ASR) suppression effect. The purpose of this study was to identify the chemical and physical characteristics relating ASR suppressing effects. The equipment used was a scanning electron microscope (SEM) combined with, backscattered electron (BSE) detector, energy dispersive X-ray spectrometer (EDS) and electron backscattered diffraction (EBSD). Authors classified FA particles into six phases quantitatively by feature analysis and gave particle size distribution and specific surface area of each phase. The classified particles as mullite dispersed in Si-rich glass matrix showed a strong negative correlation with 14-day expansion of mortar bar evaluated by ASTM C 1260. Judging from the results obtained in this study, specific surface area of Si-rich glass accompanying mullite crystals is revealed to be the key for the ASR suppressing effect of FA.
