One effective method for preventing corrosion of steel reinforcement and improving the mechanical properties of concrete is changing the physical nature of concrete by adding different materials. In this study, we have used polypropylene fibers as an additional material. We have compared the corrosion rate of rebar using different volume ratios and sizes of polypropylene fibers. Reinforcement potential increased as the amount of fibers increased from 0 to 2 kg m -3. The polypropylene fibers delay the initial corrosion process by preventing cracking, thereby decreasing permeability of the concrete. In addition, the corrosion rate of concrete samples made with Kish Island coral aggregate was compared to samples made with a siliceous aggregate. The corrosion rate in this concrete is more than twice that in siliceous concrete. We concluded that coral aggregate is improper for making concrete and using in concrete structures in the onshore atmosphere. © 2012 Elsevier Ltd. All rights reserved.