الفهرس 
Introduction and object of investigationOnly 14 pages are availabe for public view
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Abstract
The most commonly utilized material in civil engineering applications is Portland cement. Nevertheless, The processing of Portland cement causes amounts of both carbon dioxide (CO2) and toxic gases into the surrounding atmosphere. Approximately, about 0.94 tons of CO2 are emitted into the atmosphere in manufacture of 1 tons of cement. So, the cement industry accounts for 5–8% of global CO2 emissions [Teoreanu et al. (2005), Shen et al. (2008)]. In addition, The Portland cement manufacturing process needs a high energy demand, often consumed during the clinker production process [Schneider et al. (2011)].
Geopolymer cement (GPC) or alkali-activated cement is considered the best alternative material for Portland cement replacement [Berndt (2009)]. Geopolymer cement can be characterized by using an alkaline activator as a new type of green material synthesized. In contrary to OPC, geopolymer cement, does not depend on firing of limestone, which is the major method for obtaining of CO2 emission in the production of OPC [Rangan (2008)]. GPC production can reduce CO2 emissions by up to 90% for each cubic meter of OPC replaced. Geopolymer cement is produced by mixing of aluminosilicate precursors with highly concentrated alkali activated solution through complicated chemical process called geopolymerization. It is made of chains of three-dimensional replication structures of units (Si –O –Al –O)n and (Si –O –Al –Si –O –)n [El-Didamony et al. (2016)]. In three main stages, the transformation of the solid
Chapter I: Introduction and Object of Investigation
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aluminosilicate precursor into a gelatinous to semi crystalline geopolymer matrix of a highly compact structure occurred. The dissolution of the amorphous aluminosilicate source by the action of the alkali solution occurs during the first, producing a supersaturated solution of the species SiO2 and Al2O3.These species are connected together leading to the creating of gelatinous networks in poly condensation process while water is released gradually. In the final step, the gel network increased that enables the formation of a geopolymer matrix in three dimensions [Gharzouni et al. (2016)].
In this study geopolymer will be prepared by using Blast-furnace slag (BFS), Fine metakaolin (FMK), Metakaolin (MK), when sodium hydroxide and sodium silicate are used as activators.
IB. Literature survey:
IB.1. Studies on slag based geopolymers:
Maragkos et al. (2009) used slag of ferronickel as the raw material in geopolymer synthesis. Slag based geopolymer optimized by investigated the impact of the synthesis parameters on the mechanical properties of the materials produced. Results suggested that the ferronickel slag was an excellent raw material used by the geopolymerization process to produce inorganic polymers. In addition to very low water absorption (0.7–0.8 %), the materials produced under the optimum synthesis circumstances were compact and rigid, and given high compressive strength (118 MPa).
Panagiotopoulou et al. (2010) investigated the geopolymerization of blast furnace slag (GGBS) under different conditions. The testing involved the following aspects: 1) dissolution of slag in alkaline medium and the
Chapter I: Introduction and Object of Investigation
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impact of alkali ions (K or Na) on Al+3 and Si4+ dissolution, 2) Synthesis of the slag-based geopolymers and the effect of the Si/Al ratio and the type of alkaline ion on compressive strength increased and 3) Geopolymers characterization using XRD, FTIR and SEM/EDS measurements. Results showed that the blast furnace slag geopolymers had increase compressive strength with an optimum of 112,7±2 MPa. The Si/Al proportion of the started material greatly impacted the increased of the compressive strength of the geopolymer. It also discussed the microstructure of slag based geopolymers and the incorporation of Ca into the geopolymer matrix.
Kalinkin et al. (2012) investigated of granulated Cu–Ni slag geopolymerization. The mechanical activation of Cu – Ni slag in air and CO2 atmosphere (P = 105 Pa) was established using XRD, SEM-EDXA, FTIR, TEM, and isothermal conduction calorimetry. Geopolymer specimens were processed by mixing the mechanically activated slag with a sodium silicate solution (with a molar ratio of SiO2/Na2O=1.5) and cured at 20 ± 2 °C under 95 ± 5% relative humidity for up to 360 days. Mechanical activation of the CO2 slag resulted in a greater compressive strength of the geopolymer samples compared to mechanical activation in air. The compressive strength of the geopolymer specimens prepared using mechanically activated slag in air was 50.5, 74.6, 81.1, 82.8 and 89.5 MPa, after cured for 1, 7, 28, 150 and 360 days, respectively. The same values were 53.8, 77.4, 94.4, 106.0 and 119.0 MPa for the geopolymer samples prepared using slag mechanically activated in CO2, respectively. Maximum compressive strength of geopolymer samples made by used slag mechanically activated in CO2 was due to increase reactivity of slag particles during geopolymerization caused by carbon dioxide molecule