A salt ponding test was conducted on mature concrete specimens dry-stored in laboratory condition. Analysis on the various properties of concretes with fly ash addition and their implication to chloride ingress were done. Experimental result indicates that fly ash addition increases the maximum surface chloride concentration of concrete while reducing the chloride diffusivity with time. These concrete properties proved to have an important effect on the prediction of chloride ingress using error function solution to Fick's second law. Comparison of calculated chloride profile curve using three different determination methods for the time-dependent diffusion reduction coefficient, m, indicates that the experimental curve fitted chloride profile would generally lie between calculated curve using total age and average age as the time basis.