Ceramics-Silikáty 19, (3) 193 - 202 (1975)

Already the first 2 - 4-hours hydrothermal reactions between power station fly ash and CaO in a 3:1 weight ratios in paste form at 175 °C/9 atm. g. yield the CSH(I) phase and 11 Å-tobermorite, beside a hydrogarnet component having the approximate composition 3CaO.Al₂O₃.SiO₂.4H₂O. As the hydrothermal process progresses, the CSH(I) phase changes into 11 Å-tobermorite (5CaO.6SiO₂.5H₂O), the maximum content of which is found in a mixture that had been hydrated for 7 days. The CaO/SiO₂ molar ratio after 2-hours hydrothermal process was 1.73, after 7 days its value was 0.97. Mixtures of power station fly ash and CaO in the respective weight ratios 1:1, 2:1, 3:1, 5:1, 10:1, 1:2, 1:3, 1:5 and 1:10 were autoclaved; the largest relative amount of the tobermoritic type hydrosilicate phase was found in the 2:1 and 3:1 mixtures.