Effect of endogenous chloride contamination on the electrochemical and hydration responses of reinforced Belite-Ye'elimite-Ferrite (BYF) cement mortars

摘要

Carbon steel rebars passivate in Belite-Ye'elimite-Ferrite mortars, despite the initial low pH of the pore solution compared to Portland equivalents. Besides passivation ability, another important durability issue is the maximum allowed chloride content in the fresh mix beyond which passivation is prevented, normally 0.4% of chloride by cement mass for reinforced Portland concretes. This work aims to evaluate the impact of different endogenous chloride contents on the evolution of the electrochemical and physicochemical responses of reinforced mortars and neat cement pastes. It is shown that steel in BYF mortars contaminated with up to 0.4% of chlorides effectively passivate but the time needed to passivation is longer than for OPC mortars. Sodium chloride contamination was also found to retard the BYF hydration due to a delayed belite and ferrite hydration. Results showed that higher w/c ratio decreases the tolerable chloride content from 0.4%, BYF (w/c = 0.50) to 0.2%, BYF (w/c = 0.67).