Development of geopolymer using industrial waste materials

Abstract

Coal burned thermal power plants are producing large amounts of solid waste, fly ash. The disposal of this waste is a huge environmental problem at this moment. Generally, fly ash particles are very fine (< 100 µm) and mainly round shaped and glassy materials form an outer shell on it. According to several authors the attrition or grinding of this shell improves the activity of the fly ash. This paper deals with the laboratory investigation of ground fly ash based geopolymer. This material can be applied in many fields, mainly in the construction industry, e.g. non-structural elements, concrete, pavements and products, containment and immobilization of toxic, hazardous and radioactive wastes, advanced structural tooling and refractory ceramics, and fire resistant composites used in buildings, etc… In this study, the main process engineering properties of the raw materials, such as particle size distribution, moisture content, density and specific surface area are shown. Beside fly ash, red mud in different rate was used to prepare geopolymer. Systematic experimental series were carried out in order to optimize the preparation process. The particle size distribution of fly ash was measured by laser diffraction, the structure of fly ash and geopolymer was determined by Fourier Transformed Infrared Spectroscopy (FT-IR). The strength of the formed geopolymers was characterized by the uniaxial compressive strength. Additionally, leaching tests were carried out to monitor the stability of the main element of the fly ash. The product properties were studied as function of fly ash fineness. As a result of the investigation it was found that the geopolymer strength increased as function of fly ash fineness. Furthermore, it was established that the red mud had a positive effect on geopolymer strength. Therefore, the synergetic application of the above wastes is of good potential to create an industrial final product. Of course, several further experimental work is necessary to study the system from environmental point of view.

Mechanical activation of power station fl y ash by grinding – A review

“…100-150 µm maximum particle size, generated by burning of coal in the boiler of power stations and collected by mechanical separators (electrostatic and bag filters [17]. Based on the oxide composition, class C and class F fly ash can be distinguished, latter one has lower CaO and higher SiO 2 content than the previous one [23]. Their characteristic mineralogical phases are quartz, mullite, lime and hematite [13,14].…”

“…2. TEM image of MA fly ash particle after 60 min grinding time [21] 2. ábra Mechanikailag aktivált pernye szemcse TEM felvétele 60 perces őrlést követően [21] Mucsi et al [22] evaluated the variation of particle density of raw and ground fly ash. Significant increase in the particle density was observed as function of grinding time.…”

“…It can be found that the fly ash reached its material density (2.27 g/cm 3 ). Terzic et al [24] realized that the mechanical activation in vibratory mill promoted the amorphization of the fly ash product, induced the changes in its microstructure, reduced the size of the fly ash particles and increased the specific surface area, which are together prerequisites for increasing the reactivity of the material. Optimal residence time of MA was 20 minutes.…”

Power plant wastes capitalization as geopolymeric building materials

“…The trend of using of by-product materials, in the area of materials production, is likely when economic effectiveness increasing during fabrication [33]. In this context is necessary an economic evaluation of replacement of cement with geopolymer from fly ash as a possible alternative material [34].…”

Geopolymerisation of Mechanically Activated Lignite and Brown Coal Fly Ash

“…raw materials [11,12]. Fly ash is a potential raw material for geopolymers, thanks to the signicant presence of SiO 2 and Al 2 O 3 as the main components [13].…”