Design, structure, microstructure and gamma radiation shielding properties of refractory concrete materials containing Ba- and Sr-doped cements

Abstract

This paper presents an experimental study on the performance of shielding refractory concretes containing new types of cements for use in the radiation protection technology. Three concretes with corundum aggregate and special refractory inorganic cements belonging to the CaO–Al2O3, SrO–CaO–Al2O3–ZrO2, SrO–Al2O3 and BaO–CaO–Al2O3–ZrO2 systems were tested. The products formed in the hydration of these binders were detected by SEM-EDS. The linear attenuation coefficients obtained from measurements with γ quanta emitted by the following sources: 22Na, 137Cs, 60Co, 133Ba and 152Eu in the range of 80–1408 keV were determined twice, firstly after casting and drying (110 °C) of concretes, and secondly after sintering at 1400 °C. Especially, this work fills the gap in the literature providing the gamma rays attenuation properties of cement-containing heat-resistant corundum concretes in the energy region between 779 keV and 1112 keV. The experimental setup equipped with the ORTEC GMX25P4-70 High Purity Germanium detector (HPGe) cooled with liquid nitrogen was used for determination of the gamma-ray linear attenuation coefficients of new materials. The role of the cement on the compressive and bending strengths, pore structure (mercury intrusion porosimetry), phase composition (XRD, FT-IR) and microstructure (SEM-EDS) of heat-treated concretes was reported. It was found that the incorporation of Sr or Ba and Zr elements with cements improved the attenuation properties of corundum-based concretes, in comparison to the concretes containing Ca. The doping alkaline earth elements i.e. Sr and Ba were chemically bonded within both hydraulic matrix of green concretes and ceramic matrix formed in concrete through sintering at 1400 °C. Hence, these materials with gamma radiation shielding capacity are designed for special construction applications.