Effect of moisture content on the ²²²Rn mass exhalation rates for different grain-size samples of red brick and cement mortar used in Qena city, Egypt

Four different grain size fractions (0.2-0.5, 0.5-1, 1-1.8, 1.8-2 mm) of red brick and cement mortar samples at different moisture (0%, 5%, 10%, 15%, 20%) content relative to the sample mass were subjected to measuring their ²²²Rn mass exhalation rates using Alpha-Guard radon monitor, PQ 2000 PRO. The results indicated an inverse proportion between the exhalation rate and the particles size. For all studied grain size fractions, the change of the moisture content clearly affected the ²²²Rn mass exhalation rates. The exhalation rate reached its maximum value, which is two times higher than its value for the dry sample, by increasing the moisture content from 0 to 15% for red brick and from 0 to 5% for cement mortar, respectively. The current study results showed good agreement with those reported in the literature. (author)