Durability and radiation shielding performance of blended cement mortar under increased ambient temperature and sulfate exposure in arid environments.

A durable and radiation-resistant concrete is crucial for NPPs and other nuclear facilities where radiation exposure is critical. Concrete in arid regions is subjected to increased ambient temperatures, external sulfate exposure, and aggressive chemical attacks. The study examines the effect of increased ambient temperatures of 50 °C on the durability of mortar and its radiation shielding properties, in conjunction with chemical sulfate exposure. Two mortar batches were prepared: the first utilized ordinary Portland cement as the sole binder (O samples), while the second incorporated a blended binder comprising 5% Silica Fume(SF) and 65% ground granulated blast furnace slag (GGBFS) as partial cement replacements by weight (SG samples). To achieve this, experiments were conducted to assess mechanical properties, including compressive strength and flexural performance. Non-destructive techniques, such as resistivity and UPV, were used as indicators for the degradation of mortars. The attenuation coefficient was determined using Cs-137 and Co-60 gamma radioactive sources, along with an HPGe detector, at photon energies of 662, 1173, and 1333 keV, respectively. The results showed a correlation between sulfate-induced deterioration and changes in both mechanical performance and shielding efficiency, with apparent variations depending on the type of sulfate solution and exposure conditions. Overall, there was up to 65% and 23% increase in compressive strength of O and SG samples, respectively, after 120 days of sulfate exposure. The density remains unchanged for all samples after exposure to sulfate. At a photon energy of 1173 keV, the results indicated that the SG samples exhibited an increase in attenuation coefficient of approximately 23%, 15%, and 4% after exposure to Na