Numerical modelling in comsol multiphysics of a multispecies diffusion reaction problem for concrete elements

Systems of diffusion-reaction PDEs are widely applied in science and engineering to describe space and time evolution of individual entities whose cross interactions compete with their diffusion. In particular, such equations are utilized to model chemical species, increasing or decreasing their concentrations according to specific mutual interactions specified by physical chemistry and thermodynamics, while diffusing within a porous medium. In this study focus is posed on external sulfate attack in cementitious materials, an ageing process which possesses significant interest in civil engineering and exhibits deep multidisciplinary connections. The mathematical modelling of the external sulfate attack admits different levels of complexity, when including as variable a unique concentration, stoichiometrically equivalent, or several concentrations of diverse, cross interacting chemical species. This communication intends to outline a novel implementation of the above diffusion-reaction equations in COMSOL Multiphysics extsuperscript{circledR}. Preliminary 1D results involving three chemical species were critically discussed.