CARBONATION AND CORROSION POTENTIAL OF STEEL REINFORCEMENT IN POROUS CONCRETE

As porous concrete has acoustic and drainage characteristics, it is used in many concrete structures, such as pavements, reinforced panels, and so on. In this research, the mechanical characteristics, carbonation and corrosion potential of embedded steel reinforcement, such as compressive strength, percent of carbonation, capillary absorption coecient and corrosion potential, are investigated. The hydrophobic agent is poured into some mixtures to evaluate the eect of this admixture on the hardened speci cation of concrete.
It is known from results that all porous mixtures are very sensitive to the carbonation process because of their porous structure and the entry of carbon dioxide at the full depth of these concretes. Although the hydrophobic agent has no eect on the structure of concrete, for decreasing the saturation percent of capillary pores, these agents can decrease the rate of concrete carbonation. For porous structures of this kind of concrete, and the small thickness of paste layer around the steel reinforcement in comparison with conventional concrete, the rate of the carbonation process in porous concrete is faster than in conventional concrete. The results show that application of a hydrophobic agent causes a decrease in capillary absorption coecient, so, the probability of the presence of water for initiation and expansion of the corrosion process is decreased. It is found that the capillary absorption coecient has a linear relation with corrosion potential, wherein increasing the capillary absorption coe cient cause an increase in corrosion potential in the reinforcement of porous concrete, respectively. Therefore, usage of a hydrophobic agent in porous concrete mixtures not only causes a decrease in the rate of carbonation, but may also propagate the time of initial corrosion.