A study of the natural radioactivity and radon exhalation rate in some cements used in India and its radiological significance

The presence of natural radioactivity and radon exhalation from building materials contribute to the radiation dose received by human. So, it is essential to evaluate the activity levels of the primordial radionuclides (238U, 226Ra, 232Th and 40K) present in the building materials for the assessment of natural radiation dose. Cement is one of the major component of the building materials and is used on a large scale. In the present study, the commercially available cement samples of fifteen different brands were used to study the radon exhalation rate and activity concentration of 238U, 226Ra, 232Th and 40K nuclides. The radon exhalation rate was measured using the can technique, while the concentration of radionuclides content was determined by using gamma ray spectroscopy. The radon exhalation rate from different brands of cements was found in the range from 1.56 to 13.1 mBqkg−1h−1 with a mean value of 5.27 mBqkg−1h−1. The specific activity of uranium was found in the range 45.3–218.9 Bqkg−1 with a mean value of 111.2 Bqkg−1; 226Ra from 20.3 to 60.1 Bqkg−1 with a mean value of 35.8 Bqkg−1; 232Th from 18.8 to 60.1 Bqkg−1 with a mean value of 33.2 Bqkg−1 and 40K varied from 160.9 to 248.1 Bqkg−1 with a mean value of 199.1 Bqkg−1. The radiological parameters – radium equivalent activity, absorbed dose rate, annual effective dose, external hazard index, internal hazard index, gamma activity index and alpha index were also evaluated to assess the potential radiological hazard associated with these cement samples. Correlation coefficients for the different radionuclides have been evaluated and studied.