Significance of oxygen concentration on the quality of passive film formation for steel reinforced concrete structures during the initial curing of concrete

Reinforced concrete prisms with varying surface conditions (sealed, partially sealed, and unsealed) and curing environments (in air and submerged in water) were used to vary the oxygen concentration in laboratory experiments. The experiment results (current rate and half-cell potential) of these tests were used to establish the time-dependent influence of oxygen concentration on passive film formation and corrosion of the reinforcement steel embedded in concrete under various defined conditions. It was found that the adequate availability of free oxygen during the initial curing stage is crucial for the proper formation of the passive layer. This suggests ways to improve passive layer development, and thus the durability of reinforced concrete structures, through the use of curing procedures that control both moisture and oxygen availability.