One of the biggest benefits of using supplementary cementitious materials (SCMs) in concrete is the large reduction in the concrete chloride ion diffusion coefficient with age. The formation factor calculated from electrical resistivity measurements is proportional to the concrete effective chloride diffusion coefficient. Traditionally, the aging factor used in service life modeling has been determined from examination of the apparent diffusion coefficient calculated from concrete bulk diffusion experiments, lumping chloride binding and diffusion. This study proposes to use the formation factor determined from electrical resistivity tests to quantify the concrete aging parameter for service life modeling.  To determine the effect of cement chemical composition, four types of cement were tested including type I/II low alkali cement, type IL cement, type V cement and type I/II high alkali cement. silica fume, slag cement, Class F fly ash, and metakaolin was used as supplementary cementitious material (SCM) in binary and ternary blends with different replacement ratios to evaluate the effect of SCM on the concrete electrical properties with age. The electrical properties were determined at 28, 56, 91, 182 and 365 days. A discussion about the advantages and disadvantages of this method over traditional methods to quantify aging are presented.