ABSTRACT Naturally occurring radionuclides in building materials contribute to external and internal exposure and that is necessary to be investigated. In the research, 213 samples of 11 different kinds of commonly used structural and covering building materials were collected from housing and other building construction sites and from suppliers in Vietnam to measure the natural radioactivity of Ra-226, Th-232 and K-40. The measurements were carried out using low background gamma-ray spectrometry with HPGe detector. The specific activities of the different building materials varied from 0.18 -395.28, 0.10 -266.52 and 0.76 -2006.78 Bq/kg with the average values of 52.09, 55.70 and 593.5 Bq/kg for Ra-226, Th-232 and K-40, respectively. The obtained data were compared with the corresponding reported data of other countries. The activity concentration index and the annual effective dose were evaluated to assess the potential radiological hazard associated with these building materials. The results showed that the enhanced concentration values were sometimes felling into granite tiles, especially imported granite tiles. These obtained data aimed to enlarge the database on natural radioactivity in commonly building materials used in Vietnam and to support technical aspects in hazard exposure reduction
