Chloride diffusivity of the interfacial transition zone and bulk paste in concrete from microscale analysis

The chloride diffusive behavior of the interfacial transition zone (ITZ) and of the bulk hardened cement paste (HCP) in concrete is studied at the microscale level and accounts for the coupling between diffusion and binding under steady state conditions. Plain HCP is also studied as a reference. All the microstructures are obtained using the cement hydration model CEMHYD3D, and the relevant diffusive parameters are upscaled from the microscale to the mesoscale using volume averaging. The phenomena characterizing the diffusive behavior of ITZ and bulk paste are identified and quantitatively evaluated.