الفهرس 
Preparation and characterization of Eco-friendly geopolymer cements in Egypt and south Africa
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Abstract
Geopolymers can be synthesized by mixing alkaline solution with amorphous aluminosilicate precursors.The low availability of raw materials which where beneficially used in fabricating geopolymeric materials is considered as one of the main shortcomings which strongly contributeto the hindrance of mass production of geopolymer. Therefore, the motivation behind this work is the enhancement of commercial viability of geopolymer using non-widely used naturally occurring material (talc) and industrial solid wastes (red mud and de-aluminated kaolin) in geopolymerization process. Because the high crystallinity of such materials, they exposed to 1200{u00B0}C in the presence of 20 wt. % sodium hydroxide to yield highly- reactive silicate-rich-materials. The impact of untreated and thermochemically-treated materials on the performance of alkali activated slag (AAS) -based geopolymerwas evaluated. Accordingly, slag was individually replaced by different contents (10, 20, and 30 wt. %) of untreated and treated materials then activated by 3wt. % sodium hydroxide. The results revealed that all untreated materials have negative impact on the properties of AAS.In contrast, alkali activated slag containing 10 wt. % thermally- treated materials demonstrated the high mechanical properties. For thermally-treated talc and red mud, the increase in replacement level to 20 wt. % has resulted in the reduction of compressive strength values but still higher than those of control sample at all curing ages. Complementary, the content beyond 30 wt. % caused reduction of compressive strength to be lower than a considerable that of net alkali activated slag For thermally treated de-aluminated kaolin, the content beyond 10 wt. % led to a significant reduction in compressive strength