The effect of the extension of the curing period and exposure time to a chloride source on the transport of these ions has been studied in concrete with 100% Portland cement (OPC) and with ternary cement composed of 64% OPC, 30% blast furnace slag (BFS) and 6% limestone filler (LF). The extension of the curing time (from 28 to 90 days) did not significantly affect the transport, even in concretes with supplementary cementitious materials (SCM’s). The exposure time to the chloride source (3, 6 and 12 months) is a parameter which had a major influence on the transport. At least 6 months of exposure were necessary to achieve stable chloride diffusion coefficients with more noticeable stabilization occurring when SCM’s were used. The presence of BFS significantly decreased the transport, due to its ability to combine chloride rather than the refinement of capillary pores as a consequence of its late hydration.