This study built theoretical and practical models to evaluate the corrosion resistance of concrete for coastal offshore structures in Vietnam. A mathematical model was developed in the form of a system of nonlinear partial differential equations characterizing the diffusion "free calcium hydroxide" in a solid of a concrete structure. The model describes the process of non-stationary mass conductivity observed in the "concrete structure-marine environment" system under non-uniform arbitrary initial conditions, as well as combined boundary conditions of the second and third kind, taking into account the nonlinear nature of the coefficients of mass conductivity k and mass transfer β. It was shown that the solution of the boundary value problem of non-stationary mass conductivity allows us to conclude about the duration of the service life of a concrete structure, which will be determined by the processes occurring at the interface: in concrete-mass conductivity, depending on the structural and mechanical characteristics of hydraulic structures, and in the liquid phase-mass transfer, determined by the conditions of interaction at the interface of the indicated phases.
Keywords: Fourier numbers; concrete corrosion; free calcium hydroxide; mathematical model; non-stationary mass transfer; reinforced concrete structure.