Electrical resistivity of modified green aggregate mortars under chloride ion erosion: Experiments and coupled multi-field simulations

Electrical resistivity plays a crucial role in evaluating durability and predicting ion transport, particularly in chloride-rich environments. To enhance both performance and sustainability, waste glass and waste rubber were incorporated into cement-based materials as green aggregates and subjected to a combined chemical–physical modification. This study investigates the effects and underlying mechanisms of these modified green aggregates on the electrical resistivity of cement-based materials and further explores their electrical response under chloride ion erosion through experiments and simulations. The results show that the modified glass (MG) and modified rubber (MR) specimens exhibited increases in electrical resistivity of 57 % and 42 %, respectively, at 90 days compared with the baseline specimens. Microscopic analysis suggested that this improvement was primarily due to a densified interfacial transition zone, increased pore tortuosity (5.52 and 4.78), and higher fractal dimensions. Under chloride ion exposure, the MR specimens exhibited the highest electrical resistivity and superior chloride resistance, with a diffusion coefficient of 0.51 × 10⁻¹ ¹ m²/s and a resistivity of 113.91 Ω·m after 90 days. An Electric Field–Chloride Ingress Coupling Model was developed to simulate the electrical response of modified aggregate mortars under chloride diffusion, showing R² values exceeding 0.9 for most specimens. These findings demonstrate that modified green aggregates not only enhance the durability and electrical performance of cement-based materials in chloride-rich environments but also contribute to the sustainable recycling of waste glass and rubber.