Multi-scale modeling of the ionic diffusivity of cement-based materials

A new multiscale numerical approach was presented to predict the ionic diffusivity of cement based materials, which incorporated the lattice Boltzmann method, the conjugate gradient method, and the random walk method. In particular, the lattice Boltzmann method was applied to model the ionic diffusion in pore space of cement paste, while the upscaling of effective ionic diffusivity from cement paste (mortar) to concrete was processed by means of the conjugate gradient method and the random walk method. A case study was then presented, i e, the chloride diffusivity of concrete affected by sand content and gravel content. It is shown that the results of numerical prediction agree well with those of experimental measurements adopted from literatures. The multiscale numerical approach provides a prior assessment of ionic diffusivity for cement based materials from a microstructural basis.