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Διερεύνηση παραμέτρων αλκαλικής ενεργοποίησης αποβλήτων

Kamperopoulou Kleoniki

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Summary

Geopolymerism is considered to be an excellent choice for the valorization and management of mining-metallurgical and construction and demolition wastes (C&D wastes). Every year, enormous quantities are produced from the mining and metallurgical industries and remain untreated causing serious environmental problems. Therefore, there is an imperative need for their management through this technology. Geopolymers are materials that result from the chemical reaction between aluminosilicates with caustic and alkaline silicate solutions. Many waste and by-products, such as coal combustion ash, metallurgical slag and C&D wastes, can be used to produce geopolymeric concretes. The purpose of this thesis is to investigate the parameters that affect alkaline activation of wastes for the synthesis of geopolymeric products. The materials studied in this thesis are brick (B), tile (T), glass (G), fly ash from Megalopolis (FA), laterite from Kastoria (LK) and Polish slag (PS).As far as the experimental process is concerned, the C&D materials (B, T, G) were initially crushed using a jaw crusher and then grounded at different times in order to produce a powder with small particle sizes (d50<53 μm). The remaining materials were grounded directly in the laboratory mill for one hour each, also for the production of material with small particle size (d50<100μm). In order to investigate the parameters that play an important role in the synthesis of geopolymers with good mechanical properties, quantitative and qualitative analyses were carried out using the following techniques: X-ray fluorescence spectroscopy (XRF), Χ-ray diffraction analysis (XRD), infrared spectroscopy (FTIR) and thermogravimetric analysis (TG) providing important information on the morphology and microstructure of the produced geopolymers. The structure of geopolymers is shown to be associated with high compressive strength. As far as the theoretical part of this thesis is concerned, since there was no synthesis of geopolymers to observe and investigate the appropriate factors for their desirable properties, a comparison between the materials involved in the present diploma thesis and other related materials from other studies and investigations was carried out. Based on the characteristics of the materials from a variety of studies, (based on chemistry and granulometry) it was studied whether the investigated materials had similar properties. Apart from chemistry and granulometry, there are other factors that play a catalytic role in yielding high compression and flexural strength for the geopolymers, such as the mineralogy of the starting materials, the concentration, the type and pH of the alkaline activating solutions, the curing temperature and time as well as the ageing period. Consequently, based on the characteristics of the studied materials, it was examined whether they could be appropriate for the synthesis of geopolymers with good mechanical properties. 

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