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Δυνατότητα γεωπολυμερισμού αποβλήτων από εκσκαφές, κατασκευές και κατεδαφίσεις (ΑΕΚΚ)

Vlachou Antigoni

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Summary

Construction and demolition waste (CDW) is one of the largest volume waste streams. The management of such waste, in order not to avoid land disposal causing negative environmental impacts, such as cotamination of the soil and atmosphere and aesthetic degradation of the region, is a major challenge in recent years. Geopolymerization is an attractive, simple and alternative method of effective management of CDW for the production of high value-added components.The present master thesis aims to investigate the geopolymerization potential of construction and demolition waste. The effect of various factors, such as the molarity of the alkaline activating solution, the curing temperature, the ageing period and the particle size of the raw materials on the compressive strength of the final products is studied. The co-geopolymerization of CDW and various by-products and wastes, such as slag, fly ash and red mud and other materias such as glass and silica sand is assessed. For the synthesis of geopolymers, concrete, bricks and tiles collected from various demolished buildings were mixed with the activating solution (KOH or NaOH, deionized water and Na2SiO3). Various synthesis conditions (curing at 60–90 °C, 8–14 M KOH or NaOH molarity, particle size) have been considered. Results have shown that tiles and bricks are well geopolymerized, reaching a compressive strength of 49.5 and 57.8 MPa, respectively, while concrete shows limited geopolymerization potential since it reaches a compressive strength of only 14 MPa. CDW geopolymers synthesized under the optimum conditions were also subjected to high temperature heating for one hour, freeze–thaw cycles and immersed in distilled and sea water for one, two and three months to assess changes in their structural integrity. Analytical techniques, X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TG) were used for the identification of the morphology and microstructure of the final products.

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