Insights into the effect of the mineralogical composition of serpentine aggregates on the radiation attenuation properties of their concretes

Antigorite, lizardite, and chrysotile are the most important polymorphs of serpentine. In this work, we investigate the physical and radiation shielding properties of three serpentine concrete mixes containing the three serpentine polymorphs. The physical properties were evaluated in terms of density, water absorption and porosity. The shielding characteristics against fast neutrons and gamma-rays were determined. Attenuation measurements were conducted via the transmission method using a PuBe neutron source, which was utilized as a mixed-field source for fast neutrons and gamma-rays over the energy regions of 0.8-11 and 0.4-8.3 MeV, respectively. The experimental data were compared with the NXcom program results, and an excellent agreement was observed. This study showed that the antigorite-based concrete has a relatively higher attenuation efficiency against gamma-rays and fast neutrons compared with the lizardite- and chrysotile-based concretes. This finding is discussed in terms of the effects of minerals associated with serpentine, namely dolomite (CaMg(CO3)(2)) and magnetite (Fe3O4). Further, the contributions from dolomite should be considered for the precise determination of loss on ignition (LOI). These results suggest that associated minerals with serpentine aggregates can lead to a significant variation in the efficiency of gamma-rays and fast neutrons shielding of serpentine concretes. (C) 2020 Elsevier Ltd. All rights reserved.