Studying the effect of nano lead compounds additives on the concrete shielding properties for γ-rays

In the present work the effect of concrete incorporation with two types of nano-lead compounds on its gamma-ray shielding characteristics is investigated. The concrete samples were prepared according to the local standards of building materials and doped by different percentages of PbO and PbTiO3 nano powders which were prepared using co-precipitation and oxalate precursor techniques, respectively. In addition, commercial PbO2 powder additive was used to check the effect of particle size on concrete attenuation properties. The phase composition and particle size of all the lead-oxide additives were confirmed by XRD and TEM imaging. The gamma-rays attenuation coefficients were measured as a function of the additive percentage of lead compounds for gamma-ray energies of 662, 1173 and 1332 key using Cs-137 and Co-60 sources. The microstructure changes occurred in the concrete samples doped with Pb compounds additives were probed using the positron annihilation spectroscopy (PAS) and the results were compared with that for normal concrete. The obtained data revealed that the overall defect density of the investigated samples, as seen by the positrons, decreases with increasing the nano-PbO contents which is in agreement with the determined values of the samples apparent densities. It was found that the gamma-ray attenuation coefficient of concrete doped by nano-PbO is improved. The results are explained in the view of the fine structure enhanced modification and its impact on the gamma-ray interaction probability at different energies. (C) 2015 Elsevier B.V. All rights reserved.