Effect Of Age And Concrete Cover Thickness On Steel Reinforcement Corrosion At Splash Zone In Reinforced Concrete Hydraulic Structures

Corrosion of reinforcing steel bars in reinforced concrete is considered as one of the biggest problems that face countries overlooking to the Arabian Gulf, including Iraq. The research aims to study the effect of the corrosion of steel bars in concrete structures that are exposed to wetting and drying via waves. Reinforced concrete samples were exposed to marine simulated environment for 90 days using prepared system for this purpose. At the end of exposure period, polarization test was implemented to measure the actual corrosion rate in each sample. After that, the corrosion process was accelerated using "impressed current technique" by applying a constant electric current (DC) to the reinforcing bars. Depending on the corrosion current in natural conditions which was measured in polarization test, periods of exposing samples to accelerated corrosion current so as to maintain virtual exposure ages of 5 and 25 years of exposure to natural corrosion, were calculated. The results showed a remarkable increase in the corrosion current of steel bars in samples that had lower concrete cover thickness. The increase in the cover thickness from 20mm to 40 and 65 mm had a significant effect on reducing the corrosion current at the age of 90 days to about 70% of its original value, in both cases. At the virtual exposure age of 5 years, the reduction percentage in the corrosion current resulted from increasing cover thickness from 20mm to 40 and 65 mm were 43% and 79 % respectively.

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