Simultaneous use of bismuth trioxide and mill scale for ternary blended geopolymer composite in radiation shielding applications

The present study evaluates Mill scale which is a steel industry waste and bismuth trioxide simultaneously as a potential radiation shielding material in geopolymer composite. An innovative and first of its kind lead-free design has been developed for making radiation shielding materials using mill scale and bismuth trioxide as shielding aggregates and industrial wastes such as fly ash and blast furnace slag as precursors for the geopolymer composite. The mill scale and bismuth trioxide based composite material are characterized for their radiation shielding characteristics based on shielding parameters commonly used in radiation shielding like linear attenuation coefficient (μ), half value thickness (HVT) and Mean Free Path (MVP) for 0.662 MeV energy. The determined shielding parameters are compared with traditional shielding materials like concrete with heavy aggregates. X-Ray diffraction studies have confirmed the presence of Bismuth ferrite as the major shielding phase responsible for radiation shielding. The mechanical properties of the prepared composites are determined for their strength in direct compression. Depending upon the radiation shielding parameters like linear attenuation coefficient and half value thickness an optimum dosage of mill scale and bismuth trioxide as a shielding composite to provide adequate shielding for X-Ray diagnostic and medical facilities against X-ray photons of low intensity has been recommended. The highest linear attenuation coefficient values of fly ash and slag based geopolymer composites had been observed to be 0.208 and 0.225, respectively.