ASSESSMENT OF NATURAL RADIOACTIVITY LEVELS AND RADIATION EXPOSURE IN NEW BUILDING MATERIALS IN SPAIN

Assessment of radioactivity in sand samples from eastern Nepal in perspective of radiological hazards

This study was conducted to investigate the activity concentrations of 226Ra, 232Th and 40K in the sand samples and the health hazards associated with them utilizing a NaI (Tl) gamma spectrometer. The average activity concentrations of 226Ra, 232Th and 40K were found to be 24.8 ± 10.1, 39.8 ± 16.4 and 531.3 ± 52.8 Bq kg-1, respectively. The calculated radiological hazard parameters, including radium equivalent activity, absorbed gamma dose and effective dose rate, were found to be 122.7 ± 34.0 Bq kg-1, 57.7 ± 14.9 nGy h-1 and 0.3 ± 0.1 mSv y-1, respectively. Notably, these results were observed to be below the recommended thresholds. Other measured hazard indices were also lower than the prescribed values. From a radiological perspective, the present study concludes that the sand samples do not pose any threat to human health when utilized as a building material.

Physical, Mechanical and Radiological Characteristics of a Fly Ash Geopolymer Incorporating Titanium Dioxide Waste as Passive Fire Insulating Material in Steel Structures

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.

Investigation of Building Materials' Radioactivity in a Historical Building-A Case Study

The paper investigates a possible hazard originating from natural radionuclides in building materials in a selected historical building being reconstructed for housing. Both outdoor and indoor risks were evaluated through the radiological indices and estimated doses, based on measured activities of natural radionuclides in stone and brick materials of the building. The average measured activity concentrations of radionuclides were 7.32 Bq/kg for ²²⁶Ra, 40.05 Bq/kg for ²³²Th, and 546.64 Bq/kg for ⁴⁰K radionuclides. The average total activity concentration in building materials (594.0 Bq/kg) exceeded the world average value. A correlation was found between the potassium content in the building material samples and the total activity of radionuclides. The gamma indices, Iγ, calculated for the samples, ranged in an interval of 0.26-0.60, not exceeding the restricted limit for bulk materials Iγ = 1. The average annual effective dose due to building materials was 0.53 mSv/y, which does not exceed the limit (1 mSv/y), however, it contributes to a gamma dose excess that is higher than recommended (0.3 mSv/y at the most). The bricks were responsible for a higher level of natural radiation than natural stone material. Nevertheless, based on the radiation protection requirements, it can be concluded that the building can be used for residential purposes after the reconstruction, as no significant human health impact is expected due to the radioactivity of building materials.