Finite element analysis of chloride ion penetration and service life prediction in concrete with supplementary cementitious materials

This study investigates chloride ion penetration and service life (SL) prediction in concrete, highlighting the role of supplementary cementitious materials (SCMs), such as silica fume (SF) and ground granulated blast furnace slag (GGBFS). Finite element (FE) simulations using COMSOL Multiphysics were performed with both constant and time-dependent chloride diffusion coefficients obtained from experimental data. Four concrete mixtures with varying water-to-binder (w/b) ratios and SCM contents were tested. Chloride diffusion coefficients, measured from samples exposed to a 165 g/L NaCl solution for 3, 6, 9, and 12 months, were incorporated into the simulations. The results showed that concretes with a higher w/b ratio (0.55) experienced greater chloride penetration, with diffusion coefficients ranging from 8.574 × 10⁻¹² m²/s (at 3 months) to 5.635 × 10⁻¹² m²/s (at 12 months), whereas concretes with a lower w/b ratio (0.45) exhibited superior resistance, with diffusion coefficients decreasing from 6.494 × 10⁻¹² m²/s (at 3 months) to 4.401 × 10⁻¹² m²/s (at 12 months). SCMs significantly reduced chloride penetration in both w/b ratios; SF-containing concrete achieved the lowest diffusion coefficient (1.563 × 10⁻¹² m²/s at 12 months), due to its ability to densify the concrete matrix. Time-dependent diffusion modelling improved SL prediction accuracy, reducing simulation errors to below 30%, compared to 48-75% for constant models. SL predictions further highlighted the durability benefits of SCMs: concrete with GGBFS demonstrated a potential SL of 62 years (variable diffusion model), compared to 10 years (constant model), while SF-enhanced concrete achieved even greater longevity, with SL extending up to 106 years using variable models. These findings underscore the critical importance of SCMs, appropriate w/b ratios, and dynamic diffusion modelling in enhancing durability and ensuring the longevity of infrastructure in chloride-rich environments.