Chloride ingress significantly impacts the durability and service life of concrete structures due to the risk of steel reinforcement corrosion. Extensive research efforts have been dedicated to developing testing methods for precise measurement of concrete diffusion characteristics and mathematical models to better understand this phenomenon. Traditionally, the analysis of chloride ion penetration relies on the application of Fick’s second law, which leads to the derivation of the generally known error function equation. However, non-destructive techniques, like electrical resistivity measurements, are currently gaining prominence, along with alternative service life models, such as the one proposed by Andrade et al., which is based on surface resistivity. This model, however, requires an additional input parameter called the reaction or retardation factor to account for chloride binding. This study focuses on determining of this reaction factor of the designed concrete and prediction of the service life of a theoretical structure using the traditional error function solution of Fick’s second law, diffusion, and aging coefficients for initiation time, in combination with the model proposed by Vidal and Morris to predict the corrosion propagation time; and using surface resistivity measurements on saturated specimens and the resistivity-based service life model.