Evaluation of the diffusivity and permeability of high-performance concrete (HPC) was a major task in a comprehensive strength and durability study in the Wacker Drive Viaduct Reconstruction Project in Chicago, Ill. Two main HPCs were selected. Mixture 1 included 15% slag, 10% fly ash, and 5% silica fume, and mixture 2 included 20% fly ash and 5% silica fume by cement weight. The total amount of cement plus mineral admixture in mixture 2 was 5% greater than that in mixture 1. Various local concrete producers in Illinois were contacted to supply concretes based on the proportions of mixture 1 and mixture 2. In addition, the suppliers were allowed to choose a third concrete mixture based on their experience to evaluate its suitability for meeting the defined HPC characteristics. A total of 14 concrete mixtures consisting of 8 ready-mixed and 6 precast concretes were supplied. Chloride-ion-concentration profiles and apparent diffusion coefficients were determined for each concrete from a two-year ponding in a 15% saltwater solution. The coulomb permeability tests were carried out at 56,180, and 365 days. The results revealed that the precast concretes had lesser diffusivity and permeability values than the corresponding ready-mixed concretes. For the same producer and curing conditions, the diffusivity and permeability of mixture 1 was less than that of mixture 2. The concrete properties of a given mixture varied significantly among the different producers. The coulomb value and apparent diffusion coefficient of each concrete was compatible. However, the diffusion coefficient did not correlate for coulomb values ranging from 800 to 2500. The concretes correlated better when the coulomb values exceeded 2500.
