Nanomechanical testing of gamma-irradiated building composites

Nuclear power plants worldwide are aging and will soon reach the end of their designated lifetimes. Consequently, extending their safe operation to 80 years has become the focus of extensive research. The effects of irradiation on concrete are multiscale but have primarily been studied using macroscopic samples, where a decrease in mechanical properties has been reported. This study focuses on the micro-scale effects of gamma irradiation on cement paste exposed to a wide range of relative humidities (0%–100%). Nanoindentation was employed as the main tool to quantify micro-mechanical parameters, such as Young’s modulus and hardness. A significant increase in Young’s modulus ( 25%) was found at relative humidities below 11%, attributed to the combined effects of water radiolysis and drying. In contrast, a decrease in Young’s modulus ( 26%) was observed in samples irradiated in water. Samples irradiated at medium humidities (33%–76%) showed negligible damage due to the irradiation.