الفهرس | Only 14 pages are availabe for public view |
Abstract The formation and later accumulation of excessive amounts of different industrial solid wastes obtained as by-products from certain industries represent a big pollution problem due its harmful effects on the health of human being in the surrounding areas of these industries. Therefore, the environmental mitigation and reduction of the levels of emissions of these pollutants around these industries show the utmost necessity of utilization and/or prevention of these harmful pollutants. The object of this investigation is the utilization of the different industrial solid wastes for the production of certain autoclaved building units having high performance and reasonable physico-mechanical characteristics as a result of hydrothermal reactions between pozzolanic materials and alkaline activators. The alkaline activators used are cement kiln dust (CKD) (the solid waste produced from cement industries using the ”dry process”) and hydrated lime [Ca(OH)2]. The pozzolanic materials used in this investigation are ground granulated blast-furnace slag(GGBFS) (the solid waste produced from big iron industries), rice husk ash (RHA) (as a source of active silica obtained by burning of rice husk), nano-metakaolin (NMK) (as an active pozzolanic material obtained by burning of nano-kaolin followed by activation at 800 ⁰C) and silica fume (SF) (as a sort of nano-silica obtained from silicon and ferro-silicon industries) where it condensed from the exhaust gases in the electric arc furnace during reduction of quartz). Several dry mixtures were prepared and subjected to steam under hydrothermal conditions in the autoclave at a pressure of 8 atmospheres of saturated steam for different curing ages of 0.5, 2, 6, 12 and 24 hours. The autoclaved specimens were examined for their mechanical properties (compressive strength test) and the crushed samples were ground for other physico-chemical studies; where they are characterized using X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) as well as kinetics of hydration via the determination of chemically combined water (Wn., %) and free lime contents at different autoclaved ages. |