Silica fume modified superhydrophobic cement-based materials with enhanced anti-corrosion property and its mechanism

The long-term durability of cement-based materials is inherently reliant on water migration within porous structures. This study leverages the potential of low-cost silica fume (SF), a waste-derived resource, and combines it with the "Lotus Effect" principle to create superhydrophobic silica fume (SSF), which is then used to impart superhydrophobicity to cement-based materials. The findings reveal that incorporating 4 wt% (the weight ratio of cement) of SSF into cement-based materials achieves a water contact angle (WCA) of 151.79°, effectively mitigating water penetration. Furthermore, the impedance value of the superhydrophobic cement-based materials containing 4 wt% SSF group demonstrates a nearly 100-fold enhancement in anti-corrosion compared to the Control group, accompanied by significantly reduced chloride ion diffusivity. For concrete that introduces SF and SSF, a significant negative correlation (R² > 0.99) is observed between the fractal dimension of micropores ( D₂ ) and chloride diffusion coefficients, indicating that higher fractal dimensions (i.e., more complex pore structures) effectively hinder chloride migration. These findings collectively demonstrate that incorporating SSF enhances the corrosion resistance of concrete materials, preventing Cl¯ from reaching the concrete-steel interface. Given the large-scale and efficient production capabilities of SSF, coupled with its ease of transportation, it emerges as a promising option for mitigating chemical erosion in marine infrastructures. • Utilize low-cost silica fume in combination with the "Lotus Effect" principle to design superhydrophobic silica fume. • Superhydrophobic silica fume is incorporated as a mineral admixtures within cementitious materials to obtain superhydrophobic concrete. • The impedance value obtained through the electrochemical method is two orders of magnitude higher than that of the Control group. • The chloride ion penetration resistance is analyzed by combining the fractal dimension of the pore structure with the chloride ion diffusion coefficient.