Radiation shielding and hydro-mechanical performance of bentonite-copper slag mixtures

The increasing generation of low-level radioactive waste (LLRW) demands the development of effective and sustainable landfill liner systems with enhanced radiation shielding and strong hydro-mechanical properties to ensure safe disposal. In this study, copper slag was used as an additive in proportions of 15%, 30%, and 45% to modify bentonite performance as a radiation barrier. The radiation shielding performance of the mixtures has been evaluated using experimental measurements with a Sodium Iodide Scintillation Detector (NaI(Tl)) and validated through the MCNP code simulations and data from the XCOM database. The addition of 30% copper slag led to an increase in the linear attenuation coefficient by 14% at photon energies of 662, 1173, and 1332 keV. Hydraulic and air permeability have been investigated experimentally. As the results show, although hydraulic and air permeability increase with growing copper slag content, the smallest increase was observed in the sample containing 30% copper slag content (B70C30). Moreover, uniaxial compressive strength was also examined, revealing that the sample containing 30% copper slag exhibited the highest value compared to the 15% and 45% copper slag samples. The findings suggest that the B70C30 sample is a promising candidate for application as a cover layer in LLRW disposals.