Effect of barium ion on the stability and chloride ion binding of ettringite

To lower the corrosion hazards of the steel bar in reinforced concrete, binding chloride ion by producing Cl-AFm is an effective way. In the presence of calcium ions and sulfate ions, Cl-AFm could transform into ettringite , and release the chloride ions into pore solution , with negative effect on reinforced concrete. In order to avoid the negative effect, barium ion was introduced to preferentially precipitate the sulfate ions. In this study, the effect of barium ion on the transformation reaction of ettringite into Cl-AFm was studied, and the combination effect of barium ion and sulfate ion on chloride binding was discussed. The results showed that barium ion could improve the chloride binding capacity of ettringite. The mechanism was that barium ion could be precipitated by sulfate from AFt to form BaSO 4 , and then result in the formation of Cl-AFm.