The Enhancing Effect of Nanosilicon Dioxide Content on the Chloride Ion Permeability Resistance of Cement-based Materials

Yu Xiongzhengyang

Xihua University

Abstract：

Cement-based materials have been widely used as basic materials for construction engineering and their durability has a direct effect on service life of buildings. When it comes to as marine environments and saline-alkali lands, chloride ion penetration is the core inducement leading to material deterioration and steel bar corrosion, which seriously threatens structural safety.Nanosilicon dioxide (nano-silica, NS), with its high specific surface area, excellent pozzolanic activity and micro-filling effect, can effectively optimize the internal structure of cement-based materials and improve their chloride ion permeability resistance.In this study, laboratory experiments were conducted to systematically evaluate how different nanosilicon dioxide dosages (0%, 1%, 2%, 3%, 4%, and 5% by cement mass fraction) influence the materials’ resistance to chloride ion penetration. Combined with micro-testing, the enhancement mechanism was revealed, and optimization suggestionsfor engineering applications were put forward.The findings indicate that within the 0%-3% content range, increasing nanosilicon dioxide leads to a marked reduction in the material’s chloride ion diffusion coefficient and electric flux, while its resistance to chloride penetration progressively strengthens;at 3% content, performance is optimal, with the 28d chloride ion diffusion coefficient 44.8% lower than the reference group and the 6h electric flux 52.3% lower than the reference group.;when the content exceeds 3%, the particle agglomeration intensifies, the pore structure deteriorates, and the performance decreases instead. Mechanism analysis shows that nanosilicon dioxide refines pores, generates dense hydration products and improves the interfacial transition zone through the synergistic effect of micro-filling, pozzolanic reaction and interface optimization, thereby inhibiting chloride ion migration.The study outcomes serve as theoretical foundations and engineering guidance for the appropriate application of nanosilicon dioxide in high-durability cement-based materials,and are of considerable importance for prolonging the service life of structures and reducing maintenance costs.

Key Words：

Nanosilicon Dioxide; cement-based materials; content; chloride ion permeability resistance; microstructure; hydration reaction