A harsh environment of temperature (20–54°C [68–129°F]) and humidity (80–95%) with the presence of chloride and sulfate make concrete structures vulnerable to deterioration and as a result shorten their service life span. This research has evaluated the durability of normal concrete (NC) and high performance concrete (HPC) made with two aggregates, types AA and AD. Concrete specimens were exposed to saline water in a controlled temperature and humidity environment and tested for initial surface absorption and chloride diffusion. It is observed that the NC and HPC made of type AA aggregates showed lower permeability and lower chlorides diffusion as compared to that made of type AD aggregates. HPC samples produced by the two types of aggregate have consistently shown better durability performance compared to that of NC. The results collected within 21 months period allowed the prediction of chloride diffusion with time for NC. A long term prediction of the chloride diffusion was made to estimate the service life of structures. Experimental observations of s diffusion of NC correlated better with Fick’s Second Law prediction than those of HPC.