| Abstract [eng] |
In order to reduce carbon emissions and energy costs, the binder industry is seeking alternatives to the widely used Portland cement (PC). Cements containing ye'elimite are appealing hydraulic binders, as their production requires a lower amount of calcium carbonate and a sintering temperature ~200 °C lower compared to PC. Ye'elimite plays an important role in regulating the initial stages of hydration of these cements and the final properties of concrete. Consequently, numerous scientists have shown interest in studying the synthesis and properties of ye'elimite. However, the synthesis methods currently used for pure ye'elimite require multiple sintering cycles or expensive materials and equipment. Considering this, the dissertation investigated the formation of ye'elimite using the two-stage method, including hydrothermal synthesis and calcination of the resulting product, calcium monosulfoaluminate 12-hydrate (Ms12). The work assessed how the preparation of the initial mixture and hydrothermal synthesis parameters influence the formation of this precursor and its purity, the impact of water vapour pressure on compositional changes of MS12, its thermal stability, and the mechanism of ye'elimite formation. The studies evaluated the hydration properties of synthetic ye'elimite, the effects of siliceous fly ash on its hydration, and its application to control the setting time of ordinary Portland-fly ash blended cement paste. Finally, the use of technogenic products generated in the Lithuanian industry, such as AlF3 production waste - silica gel and granite cutting waste for the production of belite-ye'elimite-ferrite cement, and the properties of the resulting mortars were determined. |
