FE2 Method for Coupled Transient Diffusion Phenomena in Concrete

Acoupled finite-element squared (FE2)-framework is formulated and employed for simulation of a transient and coupled moisturechlorideion diffusion problem in concrete. Simulations are carried out on the macroscale, where the material response is obtained concurrentlyin the computations by introducing a representative volume element (RVE) in the macroscale quadrature points. The RVE, in turn, contains themesoscale heterogeneities of concrete in terms of cement paste, aggregates, and interfacial transition zone (ITZ). In this fashion, the RVE comesto serve as a constitutive model for the macroscale.Anumerical example is given to show how the transient macroscale diffusion is influenced bythe composition of the mesoscale constituents. Parametric studies were carried out with respect to the aggregate content within the RVE, bothincluding and excluding the ITZ, and the coupling parameters of moisture and chloride ions