论文部分内容阅读
In India, the generation of electricity is very much dependent on combustion of local coal and the coal fly ash generation is to be over 190 million tons in 2014-15.Most of the fly ash available in India is of low lime,class-F fly ash (ASTM C-618) which shows a high degree of variability in the quality, higher percentage of crystalline phases and relatively low glassy phase that accounts for lower usage in cement and concrete.The commonly used lime reactivity test used for assessing the pozzolanicity of fly ash did not always correlate with the observed reactivity in cement activity tests (ASTM C-618).If time scale of measuring the fly ash reactivity is reduced it can benefit the testing & use in the cement plants.This paper presents an over view of the results of a number of different methods to study reactivity of fly ashes including (i) fly ash characteristics : fineness,amorphous /glass content (microscopy, X-ray diffraction, acid / base treatmen), bulk chemistry (ii) Lime reactivity (IS 1727) (iii) Activity index.The paper will identify the relative effectiveness in assessing the fly ash reactivity.Conductivity method proposed shows a fair correlation to lime reactivity and poor correlation with cement activity index.It can also be used for finely ground fly ashes.