Performance Evaluation of Nano-SiO2, Nano-Al2O3, and Nano-CaCO3 Admixed Cementitious Composites

Abstract

This study evaluates the effects of Nano-SiO2,Nano-Al2O3, and Nano-CaCO3 on the fresh, mechanical, electrical, corrosion, and microstructural behavior of cementitious composites. A slight decrease in workability was observed in nano-silica mixes due to its high surface area, while nano-calcium carbonate improved mix cohesion. All nano-modified concretes exhibited higher compressive strength, with nano-silica providing the greatest improvement as a result of its strong pozzolanic reaction and ability to refine the microstructure. At a 3% replacement level, all three nanomaterials significantly enhanced overall performance. Durability assessments further showed higher electrical resistivity in nano-modified mixes, reflecting reduced ionic penetration. Corrosion studies using potentiodynamic polarization after 90 days of exposure indicated substantial improvements, especially under aggressive environments. Concrete incorporating nano-silica recorded the lowest corrosion current density and corrosion rate in tap water, saline water, and acidic solutions, followed by nano-alumina. These enhancements are primarily linked to microstructural densification, reduced permeability, and better stability of the passive layer formed on embedded steel reinforcement.