This research analyzes whether a titanium dioxide waste (TiO2 waste) can be used as a source material for geopolymers with good fire resistance properties. Samples with different proportions were prepared, replacing fly ashes with titanium dioxide waste on geopolymers (0, 20, 30, 40 and 100% w/w). The activating solution has a Na2O/SiO2 molar ratio of 0.98. Physical (bulk density, moisture content and water absorption) and mechanical (superficial hardness and compressive strength) characteristics have been evaluated. In addition, their thermal behavior at high temperatures (fire resistance, compressive strength at elevated temperature and absorbed energy) has also been evaluated to see if they can be used as fire insulating materials. This work also studies the radiological activity of geopolymer materials. The replacement of FA with WTiO2 increases the bulk density due to its higher specific bulk density. The highest compressive strength values were obtained with a TiO2 waste content between 30 and 40% w/w. The compressive strength decreases at high temperatures, especially when more TiO2 waste is added. When the amount of TiO2 waste is increased, so is the plateau of evaporation, and this, in turn, increases the resistance to fire. Geopolymers containing FA and TiO2 waste do not present radiological problems, although, when the TiO2 waste is increased, the activity index of the geopolymer also rises.
Keywords: fire resistance; fly ashes; mechanical properties; radionuclide; titanium dioxide waste.