Influences of multiple factors on the chloride diffusivity of the interfacial transition zone in concrete composites

The corrosion of reinforcement caused by chloride attack can degrade the durability and strength of reinforced concrete (RC) structures and shorten the structural service life. The interfacial transition zone (ITZ) in concrete composites is generally considered a weak phase of chloride ingress due to its higher porosity compared to mortar and coarse aggregate. In this paper, the influences of multiple factors, including the water-cement ratio, ITZ thickness, and coarse aggregate properties, on the ITZ chloride diffusivity in concrete composites are elaborated. The results indicate that the normalized chloride diffusivity of the ITZ is affected by the factors of ITZ thickness, coarse aggregate volume fraction and coarse aggregate grading but is independent of the water-cement ratio. In particular, during the investigations of this paper, an experiential model is built to assess the normalized chloride diffusivity of the ITZ in concrete composites considering multiple factors of the ITZ thickness, coarse aggregate volume fraction and maximum coarse aggregate size. The precision accuracy for this developed experiential model is validated and examined based on mesoscopic numerical simulation using finite element analysis to determine the diffusion concentrations of chloride ions in concrete composites.