A methodology is presented that is particularly useful for evaluating mixture designs and multiple design criteria when predicting the service life of concrete structures. The methodology incorporates surface environment, chloride transport, temperature of surrounding medium, seasonal effects, and construction variability into a model that can be used to predict the service life of a reinforced concrete structure in different environments. Three components (submerged, splash zone, and superstructure) on the same concrete structure in two temperature environments are used in examples to illustrate the technique. Several concrete mixtures of different quality are evaluated in these applications. Silica fume is shown to increase significantly the estimated service life of the structures by decreasing chloride transport in the concrete and by decreasing the buildup of chloride in the near surface region of the structure.