Assessment of natural radionuclide content of cements used in Nigeria

The activity concentrations of Ra-226, Th-232 and K-40 in seven brands of Portland cement used in Nigeria have been determined using a gamma-ray spectrometer with a hyperpure germanium detector. A total of 22 samples were collected from suppliers. The mean activity concentrations varied between 19.2 and 85.1 Bq kg(-1), 12.9 and 31.7 Bq kg(-1), and 31.5 and 116 Bq kg(-1) for Ra-226, Th-232 and K-40, respectively, which are lower than the world averages for building materials. The average values of Ra-226, Th-232 and K-40 content of all the cement samples are 43.8, 21.5 and 71.7 Bq kg(-1), respectively. The results of the radium equivalent activity, external hazard index, gamma activity index and alpha index calculated were all within the recommended limits for safety, and compare well with results obtained in some other countries of the world.