Communications in Physics, Vol. 27, No. 3 (2017), pp. 193-203 DOI:10.15625/0868-3166/27/3/10034 RADIATION DOSE ESTIMATION OF CEMENT SAMPLES USED IN LAO PDR SONEXAY XAYHEUNGSY a,b, † , LE HONG KHIEM b,c , AND LE DAI NAM b,c a Faculty of Science, The National University of Laos, Lao PDR b Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi, VietNam c Institute of Physics, Vietnam Academy of Science and Technology, 10 DaoTan, Ba Dinh, Hanoi, VietNam † E-mail: sonexaysy@gmail.com Received 24 September 2017 Accepted for publication 23 October 2017 Published 02 November 2017 Abstract. The natural radioactivity due to the presence of 226 Ra, 232 Th and 40 K radionuclides in Lao PDR cements was measured for the first time using a gamma-spectrometry with HPGe detector. Two different types of cement produced by 4 local cement companies in Lao PDR have been investigated. The specific radioactivity of 226 Ra, 232 Th and 40 K in the investigated samples ranged from 24.83± 1.18 to 54.39 ± 5.90 Bq kg −1 with a mean of 37.76 ± 10.71 Bq kg −1 , 6.63 ± 1.59 to 21.17 ± 0.48 Bq kg −1 with a mean of 13.77 ± 5.85 Bq kg −1 and 43.28 ± 7.68 to 168.70 ± 3.34 Bq kg −1 with a mean of 116.07 ± 47.50 Bq kg −1 , respectively. The radium equivalent activity (Ra eq ), the gamma-index, the external and internal hazard indices, Absorb Dose Rate in Air (D) and Annual Effective Dose Equivalent (AEDE) were estimated for the radiation hazard of the natural radioactivity in all cement samples. The obtained results were compared with the corresponding values for cement of different countries. The calculated Ra eq values of Lao PDR samples are lower than the limit of 370 Bq kg −1 set for building materials. The mean indoor absorbed dose rate is slightly lower than the population-weighted average of 84 nGy h −1 while the corresponding effective dose was 79% less than the dose of 1 mSv y −1 . The results obtained in this study show no significant radiological hazards arising from using Lao PDR cement for construction of houses. Keywords: Gamma-ray spectrometer, natural radionuclides, cement, Laos PDR, radiation hazards. Classification numbers: 91.65.Dt; 87.55.N-. c 2017 Vietnam Academy of Science and Technology