Mechanical, thermal, structure and radiation shielding efficiency of natural kaolinite-based composites reinforced with heavy metal oxides

In this work, a low-cost, natural kaolinite-based matrix reinforced with gypsum and ground marble waste was prepared with the aim of developing materials suitable for radiation shielding applications. The prepared matrix was reinforced with a fixed 30 wt% of various metal oxides, including bismuth oxide (Bi2O3), tungsten oxide (WO3), copper oxide (CuO), iron oxide (Fe2O3), and titanium oxide (TiO2). The prepared clay composites were characterized using X-ray diffraction (XRD) to determine the crystalline phases, Fourier transform infrared (FTIR) spectroscopy to study the chemical bonds, and Scanning electron microscope (SEM) to evaluate the surface morphology and the distribution of the additives within the matrix. The mechanical and thermal properties of the composites were also evaluated, along with their efficiency in attenuating gamma rays at different energies. The results showed that reinforcing the natural matrix with different oxides led to a significant improvement in density and thermal stability, as well as a marked increase in radiation attenuation coefficients compared to the unreinforced matrix. The shielding efficiencies for a 3 cm thickness were 35.14, 38.16, 39.67, 40.67, 43.33 and 45.51% for Reference, C-Ti, C-Fe, C-Cu, C-W and C-Bi, respectively. The clay sample reinforced with CuO exhibited the highest mechanical strength, while the clay sample reinforced with Bi2O3 exhibited the highest shielding efficiency due to the high density. These results confirm the potential use of the proposed composites as environmentally friendly and low-cost building materials for radiation shielding applications.