Assessment of the natural radioactivity and radiological hazards in Turkish cement and its raw materials

The natural radioactivity due to presence of 226Ra, 232Th and 40K radionuclides in raw materials, intermediate products (clinker) and end products (22 different cement types) was measured using a gamma-ray spectrometry with HPGe detector. The specific radioactivity of 226Ra, 232Th and 40K in the analyzed cement samples ranged from 12.5 ± 0.3 to 162.5 ± 1.7 Bq kg−1 with a mean of 40.5 ± 26.7 Bq kg−1, 6.7 ± 0.3 to 124.9 ± 2.5 Bq kg−1 with a mean of 26.1 ± 18.9 Bq kg−1 and 64.4 ± 2.3 to 679.3 ± 18.2 Bq kg−1 with a mean of 267.1 ± 102.4 Bq kg−1, respectively. The radium equivalent activity (Raeq), the gamma-index, the emanation coefficient, the 222Rn mass exhalation rate and the indoor absorbed dose rate were estimated for the radiation hazard of the natural radioactivity in all samples. The calculated Raeq values of cement samples (37.2 ± 8.7–331.1 ± 15.5 Bq kg−1 with a mean of 98.3 ± 53.8) are lower than the limit of 370 Bq kg−1 set for building materials. The Raeq values were compared with the corresponding values for cement of different countries. The mean indoor absorbed dose rate is slightly higher than the population-weighted average of 84 nGy h−1.