Journal of Materials Science and Engineering with Advanced TechnologyAuthor's: Benjamin Varela, Pedro Bandeira Tavares, Amândio Teixeira Pinto and João Castro-Gomes
Pages: [17] - [33]
Received Date: November 17, 2012; Revised December 19, 2012
Submitted by:
Alkaline activation is under great attention as a useful process for producing other sort of binders than Portland cement. The great majority of the researchers are mainly focussed in low calcium alumino-silicates, such as metakaolin, fly ashes, and more recently mine tailings. Fewer works are available where the use of other kind of alumino-silicates is considered. However, in these cases, very rarely the chemical composition of such alumino-silicates when used as precursor materials allows the obtaining of a complete reaction with an alkaline solution. The development of the alumino-silicate gel structure mainly depends on the Si/Al ratio of precursor materials. Consequently, a major part of alumino-silicate materials although having rich content in alumina or silica cannot be used as precursor materials, unless adjustments of their chemical compositions are made. This paper presents a research work, which intends to demonstrate the feasibility of alkaline activation of most alumino-silicate materials by adding other source materials of different chemical composition in adequate proportions. The study was carried on two different volcanic ashes by adding some quantities of waste water sludge and glass powder. The results obtained in terms of mechanical performance and chemical stability demonstrated that alkaline activation was clearly improved in such blended materials. This could favour the alkaline activation of a larger range of materials, for example, those having negative environmental impacts.
alumino-silicates, alkaline-activation, chemical synthesis, infrared spectroscopy, X-ray diffraction, mechanical properties.
