Fabrication and characterization of geopolymer-Y2O3 composites: Microstructure, charged particles and neutron shielding properties

Abstract

Radiation shielding is one major and most effective radiation control measures that is adopted in all radiation facilities. Concrete is a traditional shielding material whose applications has remained popular even in modern nuclear radiation control. The nature of additive(s) is important in modifying the shielding efficacy of geopolymer paste and by extension concrete samples. This research, focuses on the influence of yttria (Y2O3) on the physical, mechanical, and (electrons (e-), protons (p+), alpha particles (α), heavy carbon (C) ions, and fast neutrons) radiation shielding properties of geopolymer (GEO) made from metakaolin. Three batches of the GEO-Y2O3 composite were prepared containing 0, 10%, and 20%, by weight of Y2O3. The densities of the samples were calculated as 2.28, 2.52 and 2.37 g/cm3, while the estimated hardness values were 603, 664 and 649 HV for GEO, GEO-10Y and GEO-20Y samples, respectively. The characteristics cristobalite and mullite peaks of SiO2 observed in the spectrum of GEO was conserved in the Y2O3-doped GEO samples. Comparatively, the stopping powers of e−, p+, α, and C in the GEO-xY follow the order: GEO > GEO-10Y > GEO-20Y At 15 MeV, the value of the projected range in GEO, GEO-10Y, and GEO-20Y is 1410 μm, 1470 μm, and 1610 μm for p+; 128.62 μm, 140.33 μm, and 154.55 μm for α; and 13.83 μm, 15.27 μm, and 16.86 μm for C, respectively. The value of ΣR for GEO, GEO-10Y, and GEO-20Y is 0.07495 cm−1, 0.06522 cm−1, and 0.05880 cm−1, respectively. An optimum concentration of 10 wt% of Y2O3 improved the density and hardness of the geopolymer, why the effect of yttria on the shielding behavior of the geopolymer varies with radiation quality. Yttria-doped geopolymer can be used to produce effective particle or fast neutron shielding mortar or concrete.