Shielding performance of heavy-weight ultra-high-performance concrete against nuclear radiation

Heavy-weight conventional concretes are traditionally used for shielding against nuclear radiations. However, mechanical properties and durability of conventional concrete are reported to be far less than that of ultra-high-performance concrete (UHPC) made with ultrafine materials and fibers without coarse aggregate ensuring a highly densified microstructure. Recently, many studies are reported in the literature focusing on the development of UHPC mixtures and evaluation of their performance in terms of mechanical properties and durability characteristics. The information pertaining to the performance of UHPC mixtures against nuclear radiation is lacking in the literature. In the present study, five mixtures of heavy-weight ultra-high-performance concrete (HWUHPC) were considered by partially replacing the sand with hematite powder that had ultrafine particles and about two times heavier than the sand. The dry density of the HWUHPC mixtures varied from about 2600 kg/m³ to 2900 kg/m³, all satisfying the requirement of minimum dry density for being considered under heavy-weight category. Although the HWUHPC mixtures had different dry densities, their mechanical properties did not vary significantly and showed no adverse effect of the replacement of sand. The radiation shielding increased with increase in the dry density of the HWUHPC mixtures. However, the radiation shielding of the HWUHPC was found to be higher as compared to that of the heavy-weight conventional concrete having same dry density, indicating that the denseness of the microstructure also improves the radiation shielding besides the density of concrete.