Effect of nano ferrosilicon and heavyweight fine aggregates on the properties and radiation shielding of ultra-high performance heavyweight concrete

Minerals such as ilmenite and magnetite better absorb gamma rays compared with silica aggregates because of their elevated densities. However, utilizing such minerals as key elements in ultra-high performance heavyweight concrete (UHPHWC) demonstrates promising outcomes, in addition to the enhanced tensile strength of the optimum radiation absorber for nuclear sites. This paper presented ilmenite and magnetite separated from black sand for use as substitutes for fine aggregates in the production of UHPHWC. In addition, nano ferrosilicon (NFS) at 1%, 2%, and 3% of the cement mass was developed using a mechanical method and mixed into the UHPHWC mixes. Their effects on the microstructure, gamma-ray attenuation coefficient, mechanical properties, and density of UHPHWC were explored. The total replacement of fine sand with ilmenite and magnetite enhanced the attenuation efficiency of the concrete mixes by 18.9% and 24.2%, respectively, after 28 days. The addition of 3% NFS to produce UHPHWC achieved the highest compressive strengths of 130.5, 167.2, and 189.8 MPa after 7, 28, and 91 days, respectively. In addition, the combination comprising 3% NFS and 100% magnetite acquired the maximum density and gamma-ray attenuation coefficient values.