Computational homogenization of diffusion in three-phase mesoscale concrete

Artikel i vetenskaplig tidskrift, 2014

A three dimensional (3D) mesoscale model of concrete is presented and employed for computational homogenization in the context of mass diffusion. The mesoscale constituents of cement paste, aggregates and Interfacial Transition Zone (ITZ) are contained within a Statistical Volume Element (SVE) on which homogenization is carried out. The model implementation accounts for ITZ anisotropy thereby the diffusivity tensor depends on the normal of the aggregate surface. The homogenized response is compared between 3D and 2D SVEs to study the influence of the third spatial dimension, and for varying mesoscale compositions to study the influence of aggregate content on concrete diffusivity. The computational results show that the effective diffusivity of 3D SVEs is about 40% greater than 2D SVEs when ITZ is excluded for the SVE, and 17% when ITZ is included. The results are in agreement with the upper Hashin-Shtrikman bound when ITZ is excluded, and close the Taylor assumption when ITZ is included.