Valorization of steel slag into sustainable high-performance radiation shielding concrete

Abstract

The disposal of steel slag (SS) has become a serious ecological problem due to the waste of massive land resources. This study reveals the huge potential of recycling SS as heavy aggregates to develop radiation shielding concrete (RSC). The physical characteristics, radiation attenuation capabilities, microstructure, and environmental and ecological impacts of SS-based RSC are comprehensively evaluated and compared with those of normal concrete and the commonly used heavy concrete. The test results indicate that SS-based RSC is prospective to substitute the commonly used heavy concrete, emerging as a sustainable and efficient material for radiation shielding in nuclear energy engineering. Specifically, due to the reaction of cementitious active substances in the surface of SS, the developed SS-based RSC exhibits a fantastic interfacial transition zone (ITZ), and a compact pore structure, thereby showing excellent mechanical properties. The maximum compressive strength of developed SS-based RSC reaches 47.4 MPa. In terms of gamma ray attenuation property, due to the introduction of heavy nuclei and the increase in density, the gamma ray attenuation capacity of developed SS-based RSC is 17.2 % higher than that of normal concrete. The neutron attenuation property is also slightly enhanced due to the refinement effect of SS on pore structure of RSC. Life cycle assessment and unit cost evaluation results demonstrate that compared with barite based-RSC, SS-based RSC can save 97.6 % in cost, 52.0 % in energy consumption, and 70.4 % in carbon emission. The developed SS-based RSC exhibits excellent mechanical properties and radiation attenuation capacities, contributing to the further application of radiation shielding materials. Besides, this approach achieves the high-value recycling of SS, providing new insights for the utilization of high-density solid wastes.