A new diffusion model of sulfate ions in concrete

Sulfate attack is one of the major durability problems in concrete structures. Sulfate ions present in concrete can react with cement hydration products to form gypsum and ettringite, and this may affect the pore structure and cause structural damage. In this paper, an experimental study was performed on the diffusion of sulfate ions in concrete. Based on the experimentally obtained results, a new diffusion model for sulfate ions was developed, taking into account the influence of the evolution of sulfate-induced damage on the diffusion of ions. The evolution of damage with immersion time and concentration of sulfate ions can be determined using ultrasonic tests. A numerical method was utilized to solve the nonlinear parabolic partial differential equation describing diffusion. A comparison between numerical results and experimental data is provided to validate the proposed models.