کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
144624 | 438942 | 2015 | 7 صفحه PDF | دانلود رایگان |
• Size fractioned fly ash from ESP has shown wide variation in chemistry, mineralogy, granulometry and glass content.
• Geopolymerisation reaction has shown linear relationship with glass content.
• Improvement in physical properties can be ascribed to type and nature of reaction product and compact microstructure.
• Compressive strength was influenced by SiO2/Al2O3 ratio, fineness and glass content.
• Rapid strength development in finer fraction at elevated temperature.
Fly ash is a fine powder residue resulted from combustion of pulverized coal in thermal power plants. Different size fractions of fly ash have different properties. Four size fractions (with characteristic particle diameter D50 of 40.37, 23.64, 10.33 and 2.98 μm respectively) collected from different fields of an electrostatic precipitator and representing the entire particle spectrum of fly ash has been selected for the study. These fractions have been characterized for their granulometry, chemistry, glass content and mineralogical phases. Geopolymerisation of size fractioned fly ash has been carried out at ambient (27 °C) and elevated (60 °C) temperature using isothermal conduction calorimetry (ICC) and the microstructure has been studied using X-ray diffractometry (XRD), scanning electron microscopy with X-ray microanalysis probe (SEM-EDS) and Fourier transform infrared spectroscopy (FTIR). Calorimetric studies showed that the heat flow curve during geopolymerisation has linear correlation with the glass content of fly ash. The compressive strength development at both ambient and elevated temperature was due to the combined effect of SiO2/Al2O3 ratio, particle size and glass content. SEM-EDS studies have shown more reaction product in finer fractions and unreacted particles in coarser fractions. Formation of more thermonatrite phase was due to poor reactivity of coarse size fraction resulting into free alkali which in presence of atmospheric carbon formed Na2CO3⋅H2O.
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Journal: Advanced Powder Technology - Volume 26, Issue 1, January 2015, Pages 24–30