This study investigates the chloride penetration resistance of infrastructure concrete and how its composition influences the durability of large-scale on-site components. Four concrete mixtures were prepared featuring CEM II/B, CEM II/C and CEM III/A cements partially supplemented with fly ash, limestone powder, and silica fume. Laboratory testing and drilling core sampling from large-scale on-site elements provided insights into each mixture’s mechanical and durability characteristics and about the transferability of laboratory results with on-site results. Chloride migration coefficients were determined after 28, 56, and 91 days, together with compressive strength measurements at 28 and 56 days. The results highlight substantial variability in chloride migration resistance among the concretes, with notable influences from cement type and composition. At a similar water-to-cement (w/c) ratio, the chloride migration coefficient of the concretes varied up to a factor of five, depending on the cement type used. Surprisingly, an extremely optimized concrete mixture, incorporating fly ash and silica fume at a very low w/c ratio, did not demonstrate superior chloride resistance compared to the CEM III/A mixture. This finding suggests that complex, highly modified concrete compositions do not necessarily yield enhanced durability in terms of chloride ingress resistance. Durability properties showed no direct correlation with the mechanical properties. On the other hand, the specific electrolyte resistance showed a correlation with the durability properties and seem to offer a promising, non-destructive, simple, and rapid technique for assessing chloride ingress resistance. These findings provide critical insights for selecting concrete compositions aimed at enhancing the durability of infrastructure components exposed to chloride ingress.