Formulazione di leganti ad attivazione alcalina a base di loppa di altoforno: analisi dei sistemi a base di silicati e a base di alluminati. Valutazione delle reazioni di idratazione e delle proprietà applicative

The Portland cement production is one of the most important contribution to the anthropological CO2 emissions. The alkali-activated binders could represent a valid alternative to this material in the future. In this thesis work systems based on ground-granulated blast furnace slag with solid activation have been studied. The formulations studied comprise systems based on silicates and systems based on aluminates. The first formulations have been activated by Na2CO3, and their reactivity has been improved with Ca(OH)2 and clinker. In addition to these, systems activated by clinker and Na2SO4 and clinker and CaSO4 have been tested. The second formulations have been activated by aluminous cement. The high content of Al3+ gives a refractory properties to the system; furthermore, the behaviour with retarding and accelerating agents has been studied. The formulations have been analysed through calorimetry to determinate the reactivity of the systems, then the mechanical strength has been tested in compression and splitting. The mechanism of hydration of silicate systems has been carefully analysed measurements of the pore solution composition. The aluminate systems have been tested at high temperature to evaluate the refractory properties and mechanical strength. Finally, the mineralogical evolution has been analysed by powder diffraction (XRD) and the microstructural by scanning electron microscope (SEM)