Study of Natural Radioactivity of Slovak Cements

Building materials belongs to the sources causing direct radiation exposure, therefore the natural radionuclide content of building materials is necessary to be still discussed over the world. Cements cause direct radiation exposure because of their radium (Ra), thorium (Th) and potassium (K) content. Like other construction materials, the natural level of radioactivity in cement gives rise to external and internal indoor exposure. This work is focused on the assessment of natural radioactivity of cements commonly used in the Slovak Republic. The cement samples of CEM I, CEM II, CEM III and CEM V types from the significant Slovak cement producers were analyzed in the experiment. The samples were tested for the radionuclides content by using gamma spectroscopic measurements. The radionuclides activity in the Portland cements ranged from 5.8 – 21.6 Bq kg, 16.0 – 38.23 Bq kg and 52.0 – 733.6 Bq kg for Ra, Th and K, respectively. The measured radionuclides content was compared to the specific requirements in relation to the Slovak eco-labelling process. The index of mass activity of natural radionuclides (gamma index) in cements was calculated in the range from 0.122 – 0.484.