Reinforced concrete beam specimens with the polymer modified mortar linings using a mixture of acrylic and epoxy emulsions are prepared, and exposed to a severe marine corrosion environment, where the beam specimens are continuously subjected to seawater splashes, for five years. The chloride shielding performance and durability of the polymer modified mortar linings are examined through five-year exposure by chemical analysis and EPMA area analysis. It is concluded from the test results that the polymer modified mortar linings possess an excellent chloride shielding performance and durability because of the effective 3-layer lamination of the polymer modified mortar.