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Premature failure of reinforced concrete structures which are mostly due to reinforcement corrosion. There are concrete pores, pore fluid mainly saturated Ca (OH) 2 solution, pH value is generally 12 1 3.5 between the steel is passivated. When the concrete carbonation (carbon dioxide in air through the pores of the concrete road, and concrete pore solution of Ca (OH) 2 for neutralization reaction CaCO3), the pore solution pH value decreased, reinforced in non-passivated state, the corrosion accelerated. Hot-dip galvanizing is an important way to protect reinforced concrete one, at home and abroad has more applications and research, but the pore solution pH value changes, hot dip galvanized layer and the implantation of concrete protective effect of zinc acid generated Calcium (CaHZn) Corrosion of the film changes its details are still not clear. In this paper, the pH 9 1 3.5 saturated Ca (OH) 2 solution simulated concrete pore solution, systematic study of the hot-dip galvanizing layer in these simulations Pore Solution corrosion behavior of the specimens after soaking Tafel linear polarization and electrochemical impedance spectroscopy analysis, while the corrosion products under different conditions microstructure morphology was observed by SEM, EDS component measurement and analysis of X-ray phase analysis, systematic study of the hot-dip galvanizing layer and a cover layer of hot-dip galvanized zinc calcium at different pH values ??simulated concrete pore solution soak in the process of the formation of corrosion products law, microstructure, and transformation of dissolution characteristics and electrochemical corrosion . Studies show that: hot dip galvanized layer is at a pH of 12.5 of pore fluid generated dense protective layer of zinc, calcium, zinc, calcium and pore stability is closely related to the pH value. When the pH value of 9 1 2, with the decrease of pH and immersion time increases, the reduction of zinc layer CaHZn Zn (OH) 2 increased (Zn (OH) < sub> 2 by dehydration can be transformed into ZnO), when the pH value of 9, the cover can be completely converted to Zn (OH) 2 ; when the pH is 12 1 3, the zinc layer is formed on the surface of a small amount of zinc flake calcium film; specimen icorr the corrosion current decreases with increasing calcium zincate; both these cases the zinc layer is passivated, icorr than or close 0.1μA/cm2; With CaHZn reduction and Zn (OH) 2 increase the polarization resistance (Rp), the film resistance (Rc), penetration resistance (Rct) and the diffusion resistance (Ws ) were reduced; when the pH is 12.5 13.5 when, with the elevated pH and immersion time increases, but does not produce calcium zincate dissolved Zn (OH) 2 coverage, residual calcium zinc decrease rapidly with the increase of pH, when the pH is 13.5, the surface zinc layer of the protective film is not generated, icorr was significantly increased to 102μA/cm2, significantly accelerated corrosion. For the simulation of pore fluid soaked calcium has covered galvanized zinc layer, with the decrease of pH and immersion time increases, the zinc layer of zinc, calcium reduced Zn (OH) 2 increases, When the pH value of 9, the cover can be completely converted to Zn (OH) 2 ; With zincate reduction and Zn (OH) 2 increase the polarization resistance (Rp), the film resistor (Rc), penetration resistance (Rct) and the diffusion impedance (Ws) were reduced, and the corrosion current density icorr increase, but still close to steel passivation icorr thresholds 0.1μA/cm2. When the pH is greater than 12.5, the gradual dissolution of zinc, calcium, accelerate corrosion of galvanized layer is similar to the situation. When the concrete carbonization, concrete pore solution pH decreases, as long as the pH is less than 13, a hot-dip galvanized layer and a cover layer of zinc galvanized calcium are of high corrosion resistance, to protect the steel from decades corrosion damage; But in cement with high alkalinity, pH value greater than 13 concrete pore solution, hot-dip galvanized zinc layer and a cover layer of calcium galvanized corrosion resistance decreased significantly, does not provide effective corrosion protection of steel protection. Therefore, hot-dip galvanized steel in non-high alkalinity of cement concrete with low-cost, high corrosion corrosion protection characteristics, it is worth promoting in the actual production.
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