Composite Treatment of Mortar Through Nano-Ion-Based Capillary Crystalline and Silane Hydrophobic Processing to Enhance Its Corrosion Resistance in the Cl−-Contained Environment

The inherent porous structure of concrete enables the penetration of water and Cl− ions through its pores, which eventually leads to rebar corrosion within the concrete. Consequently, the densification and impermeability of concrete protective layers play a critical role in the durability of reinforced concrete structures. This study proposes a composite anti-corrosion treatment for mortar protective layers by integrating nano-ion capillary crystalline with silane hydrophobic processing. Targeting existing mortar samples, a series of experiments were conducted, utilizing scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), differential scanning calorimetry-thermogravimetry (DSC-TG), X-ray computed tomography (X-CT), contact angle measurements, permeability tests, and electrochemical tests. These experiments systematically evaluated the effects of composite anti-corrosion treatment on the microstructure of hydration products, pore characteristics, surface hydrophobicity, impermeability, and the overall corrosion resistance of mortar-rebar samples in a Cl−-contained environment. The results reveal that nano-ion capillary crystalline materials react with free calcium ions in the mortar to produce secondary hydration products, effectively filling micro-pores, densifying the pore structure and inhibiting the invasion of Cl− ions. The combination of capillary crystalline and silane hydrophobic processing synergistically enhances surface hydrophobicity and impermeability, preventing the ingress of corrosive agents, such as Cl− ions, and significantly improving the anti-corrosion performance of mortar in a Cl−-contained environment.