부산대학교 도서관

This work was designed to correlate the dissolution kinetics of Si and Al, present in the fly ash (FA), with the mechanical strength of FA-based geopolymer. Therefore, at first, reactivity was determined by dissolving FA into 12 M NaOH solution for different dissolution times (6–24 h) at three temperature levels (20, 60, and 100 °C). Afterward, the filtrate residues were further examined by FTIR spectroscopy. Then geopolymer paste was formulated in two series by varying the alkaline to precursor ratios (0.25 and 0.35) and its compressive strength was assessed after 7 d and 160 d. From dissolution test, it was observed that the reactivity of FA increases with temperature and dissolution time, however, the trend of increment was more from 20 to 60 °C as compared to trend observed from 60 to 100 °C. It was also confirmed by FTIR spectra, as the shifting of T–O–T bond toward lower wave number was indicated, which depicted the increase in rate of geopolymerization. Moreover, the correlation matrix was developed to see the influence of temperature, reactivity and A/P ratio on the 7-d and 160-d compressive strengths. Reactivity of FA showed good correlation coefficient with temperature (0.95) and 7-d compressive strength (0.78). But, for 160-days strength the correlation coefficient decreased to 0.58. Because, at elevated temperature, geopolymerization reaction completed within few days and further strength development with age was marginal.