Radiation shielding performance of seawater-mixed concrete incorporating recycled coarse aggregate and steel slag

Abstract

Concrete production entails a high amount of freshwater consumption. Moreover, as heavy-weight concrete production is cost-inefficient for mass structures, such as radiation shielding facilities, the need for seawater and other recycled/waste materials to produce sustainable concretes for radiation shielding applications cannot be overemphasized. Hence, this paper investigates the radiation shielding performance of fresh water and seawater-mixed concrete mixes produced using various waste coarse aggregates, including recycled aggregate and electric arc furnace steel slag (EAF-SS). Partial simultaneous replacements of the two coarse aggregate types are also considered. Aimed at addressing material sustainability, a total of ten such concrete mixtures were designed and produced by varying the type of mixing water with different combinations of the normal and waste coarse aggregates while maintaining the cement content and water/cement ratio constants. These mixtures were then tested for their unit weight, compressive strength, and nuclear radiation response through gamma-ray intensity detection. The mixes' compressive strengths ranged from 30.8 to 49.8 MPa, all of which met the specifications for structural concrete. Linear attenuation coefficients were computed based on the radiation experimental results for the different mixes. Three of the specimens passed the minimum requirement to be considered heavy-weight concretes. Regardless of concrete strength, the unit weight of the mixes and the type of water (fresh versus seawater) used for mixing had an impact on radiation shielding performance. The maximum compressive strength was attained in the fresh water-mixed concrete fully incorporating EAF-SS as coarse aggregate – 13% over that of the concrete with natural aggregate. Moreover, the use of EAF-SS enhanced the radiation shielding performance of concrete by 13–19%. Using local seawater improves radiation shielding by 4–5% while pursuing sustainable concrete production for nuclear applications. A mixture's unit weight and chemical composition – particularly the existence of hematite – are crucial factors in the effectiveness of radiation shielding. The variations in gamma-ray transmission reductions between mixtures confirm the feasibility of the materials utilized.