| Title |
Influence of Air Permeability of Concrete on Corrosion of Reinforcing Steel and Carbonation of Concrete |
| Keywords |
Air Permeability ; Corrosion Rate of Reinforcement ; Carbonation ; Water-binder Ratio ; Type of Admixture Material |
| Abstract |
In the alkaline environment of concrete, the reinforcement is protected against anodic iron dissolution by a passive layer on steel surface. However, the drop in pH of the concrete pore water due to carbonation as well as chloride concentrations exceeding the threshold value will cause an extended or local breakdown of the passive layer, thus encouraging the anodic step of iron dissolution. Based on these mechanisms, the permeability of concrete such as air permeability could control a quantitative indication of potential corrosion rate. This paper reports the influence of air permeability of concrete on reinforcement corrosion due to carbonation of concrete in RC structures. The investigation has been carried out on 21 types of concrete, which are made by some parameters such as different levels of water-binder ratio, the type and replacement ratio of admixture materials, in order to measure the air permeability, depth of carbonation and corrosion rate of reinforcing steel. As a results, air permeability of concrete is related to the corrosion rate of reinforcing steel due to carbonation as well as the depth of carbonation, and the correlation coefficients are high. However, the relationship is influenced by parameters such as the water-binder ratio and the addition of admixture materials. Thus, the coefficient of air permeability may also be used in the evaluation and rehabilitation of older RC structures as well as for estimating the remaining service life in the reinforcement corrosion due to carbonation. |