Assessment of Natural Radioactivity in Cements Used as Building Materials in Poland

It has been analyzed in this article the radioactivity concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K and radiological hazard parameters in different types of cements commonly used in Poland and available on the Polish market. The radiological hazard parameters are, in particular, absorbed gamma dose rate, annual effective dose, radium equivalent activity, the external hazard index, and the gamma and alpha indices. The radionuclide activities of the most important radionuclides ²²⁶Ra, ²³²Th, ⁴⁰K have been determined by gamma-ray spectrometry with the use of two kinds of spectrometers of different operational parameters. One performed also measurements on 30-day and 45-day aged samples as to verify if there is a statistically significant difference in radioactivity concentration for shorter and longer aging time. The radioactivity concentrations in the cement samples ranged from 21.7-75.7 Bq·kg^-1 for ²²⁶Ra, 12.3-47.3 Bq·kg^-1 for ²³²Th to 123-430 Bq·kg^-1 for ⁴⁰K. The radiological parameters in cement samples were calculated as follows: mean radium equivalent activity Ra = 127 Bq·kg^-1, mean absorbed gamma dose rate D = 115 nGy·h^-1, mean annual effective dose E = 570 µSv·y^-1, external hazard index H = 0.32, internal hazard index H = 0.51, mean activity concentration index I = 0.47 and mean alpha index I = 0.28. The results were compared with the reported data from other countries and the international standard values given by European Commission (EC) and United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR 2000). Finally, thorough statistical analysis has been performed.