PREDICTION MODEL OF THE STEEL CORROSION RATE IN THE CONCRETE UNDER HIGH HUMIDITY CONDITIONS

Under high relative humidity (RE) environment condition, lots of water can be accumulated in the region between steel bar and concrete, and the corrosion rate is controlled by the oxygen diffusion. In this paper, the model of corrosion rate of steel bar, which considered the thickness of water layer and the area of oxygen diffusion, is deduced, and the experimentations are also conducted. The results show that the corrosion rate of steel bar increases with increasing the water-cement ratio, and it decreases with increasing the thickness of concrete cover. The corrosion rate is also relevant with the position of the steel bar in the concrete; the corrosion rate of corner steel bar is about 1.6-2.1 times of the central steel bar.