The influence of mineral admixtures on resistance to corrosion of steel bars in green high-performance concrete

Abstract

In this paper, the influences of the types, amount and adding approaches of mineral admixtures on pH values, electrical resistance of concrete, anodic polarization potential and mass loss ratio of steel bars in concrete subjected to 50 immersion–drying cycles were investigated. The testing results showed that the addition of mineral admixtures reduced the pH values of the binder pastes in green high-performance concrete (GHPC), especially when two or three types of mineral admixtures were added at the same time (double- or triple-adding approaches), whereas the final pH values were still above the critical breakage pH value of passivation film on the steel bar surface (11.5). Double- and triple-adding approaches also greatly increased the electrical resistance of concrete, which led to a delay in the initial time of corrosion and a decrease in the corrosion rate of steel bars. Additionally, double- and triple-adding mineral admixtures, instead of single-adding, fly ash can reduce the corrosion of steel bars when a large amount of fly-ash replacement was used. All the details of this paper provided a method to reduce or prevent the corrosion of steel bar in concrete, especially for the application in aggressive marine environments.