Radiological evaluation of the use of clay brick and pumice brick as a structural building material

In this study, clay brick (CBRICK) and pumice brick (PBRICK) samples used as structural material in the construction of dwellings, schools, workplaces and factories in Turkey were compared with each other from a radiological viewpoint. The activity concentrations of Ra-226, Th-232 and K-40 naturally occurring in CBRICK and PBRICK samples collected from different regions of Turkey were determined by using a gamma-ray spectrometer with a high purity germanium detector (HPGe). The average activity concentrations of Ra-226, Th-232 and K-40 in CBRICK and PBRICK samples were found as 35.4 +/- 3.3, 37.5 +/- 2.4 and 593.7 +/- 42.7 Bq kg(-1) and 81.9 +/- 2.5, 65.8 +/- 6.0 and 1066.0 +/- 46.6 Bq kg(-1), respectively. The radon surface exhalation rate (EXs) and radon mass exhalation rate (EXM) of CBRICK and PBRICK samples were measured by using an active radon gas analyzer with an accumulation container. The average value of EXs and EXM of CBRICK and PBRICK samples found as 45.9 +/- 2.9 mBq m(-2) h(-1) and 3.7 +/- 2.9 mBq kg(-1) h(-1) and 100.9 +/- 4.7 mBq m(-2) h(-1) and 9.9 +/- 0.5 mBq kg(-1) h(-1), respectively. Radiological parameters related to external and internal exposure to members of the public such as the radiation protection index, alpha index, and indoor absorbed gamma radiation dose rate and the corresponding annual effective dose from external exposure, annual effective dose from inhalation of radon, and the lifetime cancer risk were estimated for CBRICK and PBRICK samples. The results were compared with each other and with the international recommended limits or criteria. The results reveal that the average values measured and estimated for CBRICK samples are approximately two times lower than those measured and estimated for PBRICK samples. Thus, from the radiological viewpoint, clay brick is preferable to pumice brick as a structural material in the building sector.