Gamma Attenuation Features of White Cement Mortars Reinforced by Micro/Nano BiO Particles.

This study aims to explore the radiation protection properties of white mortars based on white cement as a binder and BiO micro and nanoparticles in proportions of 15 and 30% by weight as replacement sand. The average particle size of micro- and nano-BiO was measured using a transmission electron microscope (TEM). The cross-sectional morphology and distribution of BiO3 within the samples can be obtained by scanning electron microscopy (SEM), showing that nanoscale BiO particles have a more homogeneous distribution within the samples than microscale BiO particles. The shielding parameters of the proposed mortars were measured using the HPGe detector at various γ-ray energies emitted by standard radioactive point sources Am, Ba, Co, Cs, and Eu. The experimental values of the prepared mortars' mass attenuation coefficients (MAC) match well with those determined theoretically from the XCOM database. Other shielding parameters, including half value layer (HVL), tenth value layer (TVL), mean free path (MFP), effective electron density (N), effective atomic number (Z), equivalent atomic number (Z), and exposure buildup factor (EBF), were also determined at different photon energies to provide more shielding information about the penetration of gamma radiation into the selected mortars. The obtained results indicated that the sample containing 30% by weight of nano BiO has the largest attenuation coefficient value. Furthermore, the results show that the sample with a high concentration of BiO has the highest equivalent atomic numbers and the lowest HVL, TVL, MFP, and EBF values. Finally, it can be concluded that BiO nanoparticles have higher efficiency and protection compared to microparticles, especially at lower gamma-ray energies.