CORROSION RESISTANCE OF GALVANIZED BARS IN CONCRETE STRUCTURES EXPOSED IN THE CARIBBEAN

摘要

The aim of this research is to assess the corrosion performance of galvanized reinforcing bars in concrete elements exposed to natural tropical marine environment in the Mexican Caribbean, using limestone aggregates and ordinary Portland cement (OPC). Reinforced prisms of concrete with water to cement (w/c) ratios of 0.4, 0.5, 0.6 and 0.7 were half-immersed in seawater at a seashore site in the Yucatan Peninsula (Sisal). Corrosion was monitored by corrosion potential and linear polarization resistance measurements. The chloride penetration in the concrete was also measured. Corrosion data showed that, after 693 days of exposure, the corrosion current density values of the zinccoated bars were, 0.1, 0.08, 0.14; and 0.19 mu A/cm~2, in (w/c) ratios of 0.4, 0.5, 0.6 and 0.7, respectively. The corresponding current densities for black steel were, 0.09, 0.18, 0.32, and 0.52 mu A/cm~2. These corrosion current densities correspond to a zinc coating thickness loss of 1.2 mu m/y to 2.85 mu m/y. The corrosion rate of black steel was between 1 mu m/y and 6 mu m/y.