A comparative study of mild steel passivation embedded in Belite-Ye'elimite-Ferrite and Porland cement mortars

摘要

An extensive experimental program was designed to investigate the passivation of reinforced low carbon-release Belite-Ye'elimite-Ferrite (BYF) cement mortars compared to the passivation of reinforced conventional Portland equivalents (OPC). The influence of formulation parameters such as the water-to-cement ratio and the presence of fly ash on the steel rebar passivation was evaluated by conventional corrosion measurements such as corrosion potential readings and linear polarization resistance. Visual observations were carried out as a complement. A negligible corrosion rate was reached after 28 days with BYF cement against 14 days with OPC equivalent. This difference is attributed to the pH of the medium in the BYF mortars, which is lower than in the OPC mortars at a very early age, before becoming strongly basic. The exploitation of the Tafel slopes showed that the corrosion current can be evaluated by the Stern and Geary equation with an identical B coefficient for the samples of BYF and OPC basis. Despite some differences compared to the passivation in Portland mortars, the present study clearly points to the BYF mortars intrinsically passivating nature regarding mild steel reinforcing bars. (c) 2017 Elsevier Ltd. All rights reserved.