Evaluating the performance of red mud and hematite powder additives of clay layer used in low-level radiation waste landfills

Clay is used as the main material for the construction of landfill liners due to its unique properties such as low hydraulic permeability, self-healing performance, and availability. In addition to these properties, radiation shielding performance is a vital challenge for low-level radioactive waste disposal. In this study, the effect of two additives, including red mud and hematite are investigated on the radiation shielding and hydromechanical performance of bentonite clay. Experimental tests were performed on mixtures with 15, 30, and 45 percent of additives, and the shielding performance, hydraulic permeability, and mechanical strength have been investigated. Energy scattering (EDS) and scanning electron microscopy (SEM) tests have been performed to chemically analyze the mixture components and to define the linear attenuation coefficient by implementing simulation (MCNP code) and theoretical (XCOM database) methods. The results showed a good agreement between the experimental, simulation, and theoretical approaches. The best linear attenuation coefficient performance was reached by adding 15 percent of each additive while maintaining the hydraulic permeability and uniaxial strength in the acceptable range.