Experimental and RSM simulation assessment of Gamma-ray shielding efficiency of nano-modified concrete exposed to elevated temperatures.

This study experimentally investigates the radiation shielding performance, characterized by the linear attenuation coefficient (LAC) values, of concrete mixes incorporating lead monoxide (NL), nano-magnetite (NM), and nano-granodiorite (NG) as partial cement replacements (1-5%) under ambient and elevated temperatures (400-800 °C). The primary objective was to develop robust predictive models for the LAC values using Response Surface Methodology (RSM). Results showed that exposure to elevated temperatures notably reduced the LAC of the control concrete, especially after heating to 800 °C. Incorporating nanomaterials effectively mitigated this deterioration, maintaining higher shielding efficiency. NL mixes showed the greatest improvement, with LAC increases of about 42.6% and 37.4% after exposure to 600 °C and 800 °C, respectively. NM mixes ranked second, enhancing LAC by 26.7% and 24.2% at the same temperatures, while NG provided moderate improvement of around 9.9% at 800 °C (4% replacement). The superior performance of NL and NM mixes is attributed to their high density and atomic number, which promote photon absorption and scattering within the concrete matrix, as well as the improved microstructural integrity resulting from the filler effect of the uniformly dispersed nanoscale particles. Analysis of Variance (ANOVA) confirmed the high statistical significance and predictive power of the developed model, demonstrating an exceptional correlation between predicted and experimental data. The response surface analysis revealed that the nanomaterial dose and type are the dominant factor for enhancing LAC values, exhibiting a strong positive correlation, whereas elevated temperature has a detrimental effect. The observed curvature in the response surfaces confirmed significant non-linear and interaction effects between the input parameters. Optimization results demonstrated that a 5% nano-dose at various temperatures maximizes shielding performance, with NL identified as the most effective material, demonstrating superior radiation shielding properties.