Hydration and durability studies of nano-ferric oxide and nano-silica blended cement composites

Abstract

The long-term durability of cement-based materials in aggressive environments remains a major challenge for sustainable infrastructure development. This study evaluates the comparative effectiveness of nano-ferric oxide (nano-Fe2O3) and nano-silica (nano-SiO2) as multifunctional modifiers for improving the performance of cementitious composites, offering clear insights into their distinct roles in cement hydration, microstructural development, and durability enhancement. The incorporation of these nanoparticles modifies hydration behaviour and promotes the formation of a refined, compact microstructure by enhancing hydration product formation and pore refinement, thereby reducing pore connectivity and densifying the nano-modified cement matrix. These microstructural changes result in significant improvement in mechanical performance, with compressive strength increasing by up to 48.53% for nano-Fe2O3 and 39.74% for nano-SiO2 compared with the control mixture. The corrosion resistance of embedded steel is also substantially enhanced under both tap water and saline exposure conditions, with inhibition efficiencies of 92.03% and 56.25% for nano-Fe2O3 and 94.72% and 89.88% for nano-SiO2, respectively. These improvements are attributed to accelerated hydration, nucleation effects, pozzolanic reactions in nano-silica systems, and matrix densification, which collectively enhance the integrity of the cementitious network. From a practical perspective, the improved strength, reduced permeability, and improvement in corrosion performance suggests that nano-engineered cementitious systems can play a significant role in prolonging the serviceability of reinforced concrete structures.