| Abstract [eng] |
Influence of 5-20 % amorphous TiO2 additive on gyrolite stechiometry corresponding CaO-SiO2- H2O system during hydrothermal synthesis at 200 °C was analysed. It was determined that the additive fully intercalates into synthesis products C-S-H(I)/(II), Z-phase and gyrolite as no TiO2 compounds have formed during hydrothermal curing. XRD results established that during 4-48 hour hydrothermal curing, CSH formation and recrystalization processes are accelerated in mixtures containing 5-15 % additive. The Most notable influence is identified in mixtures with 10 % of the additive. In these products, Z-phase has fully recrystalized into gyrolite after only 16-hour hydrothermal synthesis. Additionally, the largest gyrolite diffraction peaks are identified in 24-48 hour synthesis products with 10 % additive. Full additive intercalation is confirmed by STA as DSC curves indicate no effects attributed to TiO2 recrystalization processes. During calcination in 900 °C, amorphous TiO2 reacts with CSH, forming titanite. It was determined that the additive intercalates into synthetic Z-phase and gyrolite during hydrothermal curing. Relative to productssynthesized from raw materials, the additive reacts with CSH and forms titanite during calcination. To determine the influence of amorphous TiO2 concentration and hydrothermal curing duration on titanite formation, mixtures with molar ration of CaO:SiO2:TiO2=:1:1:0.90-1.10 were hydrothermally cured for 1 and 4 hours in 200 °C. Semi-crystaline C-S-H(I)/(II) compounds were identified in all hydrothermal synthesis products. During annealing in 900 °C temperature, synthesis products recrystalized into titanite and wollastonite mixture along with traces of, calcium titanite and brookite. It was determined that in experimental conditions, the largest amount of titanite (96.91 %) is formed in calcinated products when the duration of hydrothermal curing is one hour and and the concentration of amorphous TiO2 is 1.10 moles. It was determined that additional hydrothermal curing has a positive influence on raw materials reaction processes during calcination as titanite phase is not identified in hydrothermally untreated and calcinated raw mixtures. |
