الفهرس 
Chapter (1) IntroductionOnly 14 pages are availabe for public view
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Abstract
Concrete is one of the most commonly used construction material. It is produced by using Ordinary Portland Cement (OPC) as the binder; a highly energy intensive product which releases carbon dioxide (CO2) that contributes about 7 % of the world’s carbon dioxide emissions. Thus new binders with low CO2 emissions are needed for concrete to meet the environmental demands. Among these new binders the geopolymers are highly potential solutions.
Geopolymers as binding materials consist mainly of a source material and an alkaline activator. The source materials for geopolymers based on alumina-silicates should be rich in silicon (Si) and aluminum (Al). These could be natural minerals such as kaolinite or clays or byproduct materials such as fly ash, silica fume or slag. The choice of the source materials depends on factors such as availability, cost , type of application. The alkaline liquids are from soluble alkali metals that are usually sodium or potassium based . The most common alkaline liquids used in geopolymerization is a combination of sodium hydroxide (NaOH) or potassium hydroxide (KOH) and sodium silicate or potassium silicate . Using geopolymers in concrete as binding materials, and studying the strength and durability properties of the geopolymer concrete is the aim of this research. To achieve this goal a review of previous studies and an experimental investigation were carried out and were illustrated in details throughout the different chapters of this thesis.
The literature review included the previous investigations and researches on the subjects concerning the environmental benefits of using geopolymers and geopolymer concrete, the geopolymer concrete constituents, the manufacture, the properties of geopolymer concrete.
The experimental study included 24 geopolymer concrete mixtures produced using locally available kaolinite minerals and imported fly ash as source materials, the alkaline liquid being a mixture of sodium hydroxide and sodium silicate. The main variables in the metakaolin based geopolymer concrete mixture were the content of the metakaolin in the mixture, the ratio of the silicate in the alkaline liquid to the source material and the curing temperature. As for the fly ash based geopolymer concrete mixture the main variables were the content of the fly ash in the mixture, the ratio of the alkaline liquid to the fly ash content and the molarity of the sodium hydroxide solution. The slump, density and compressive strength of the mixtures were recorded for all mixture. For the optimum fly ash mixture other mechanical tests were performed including density, compressive strength, indirect tension, flexural strength, modulus of elasticity. The resistance of the fly ash based geopolymer concrete to corrosion of steel reinforcement was also studied.
The investigation concluded that for metakaolin based geopolymer concrete the influencing factor on the compressive strength was the sodium silicate/metakaolin ratio where the increase in sodium silicate/metakaolin increased the compressive strength, also the increase in content of metakaolin, increased in compressive strength Curing was an important factor in increase compressive strength where oven curing gave highest compressive strength than ambient curing. It was also concluded that for fly ash based geopolymer concrete the influencing factor on the strength was the alkaline liquid to fly ash ratio and the fly ash content where both increased the strength. The increase in morality of NaOH solution, increased the strength, also fly ash based geopolymer concrete showed a high resistance to corrosion of steel reinforcement.