الفهرس 
INTRODUCTION AND OBJECT OF INVESTIGATIONOnly 14 pages are availabe for public view
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Abstract
CHAPTER IV
SUMMARY AND CONCLUSIONS
IV.A. SUMMARY.
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.
IV.B. CONCLUSIONS:
from the results obtained the main conclusions can be derived:
1. The autoclaved products obtained from the pastes made of mixes F1 [(60 % GGBFS - 40 % CKD) using 5 %silica fume as an additive] and F2 [(60 % GGBFS - 40 % CKD) with 10 % silica fume as an additive] possess high strength values as compared to those made without additive of silica fume. The autoclaved products obtained from these mixes possess higher mechanical properties and improved physico-chemical characteristics as compared to other autoclaved mixes. The results of this investigation revealed that these autoclaved mixes (F1 and F2) resulted in the production of high performance building products and represent the optimum constitution of autoclaved building products obtained from the wastes solid industrial.
2. The autoclaved products obtained for the hardened pastes made of mixes E1 [(70 % GGBFS – 30 % CKD) with addition of 5 % NMK] and E2 [(70 % GGBFS – 30 % CKD) with addition of 10 % NMK] have reasonable and high strength values by with improved physico-mechanical characteristics.
3. The improvement in the physico-chemical for autoclaved products made of mixes F1 [(60 % GGBFS - 40 % CKD) using 5 % silica fume as an additive] and F2 [(60 % GGBFS - 40 % CKD) with 10 % silica fume as an additive)] as well as mixes E1 [(70 % GGBFS – 30 % CKD) with addition of 5 % NMK] and E2 [(70 % GGBFS – 30 % CKD) with addition of 10 % NMK] is mainly due to the formation of calcium silicate hydrates (C-S-H) with different degrees of crystallinity at all autoclaved ages; these hydrates are characterized by its interlocking fibers which possess larger number of binding centers (points of contact) leading to the production of high performance autoclaved products.