Effects of applied voltage on chloride binding and microstructure of cement pastes subjected to chloride solutions

摘要

In this paper, the effects of applied voltage on cement paste subjected to chloride solutions were studied by comparing the microstructure and chloride binding of hardened cement pastes after bulk diffusion and rapid chloride migration (RCM) tests. The chloride concentration index, chloride binding, chemical composition and morphology of hydration products, pore structure and zeta potential of cement pastes after the bulk diffusion and RCM tests were measured. The results showed that the microstructure of cement paste was densified by the chloride binding; the applied voltage of 10 V increased the Ca/Si of C-S-H gel and modified the morphology of Friedel's salt. The chloride content of the expressed pore solution and the C-S-H bound chloride content increased when external voltage was applied, while no difference was observed for Friedel's salt bound chloride. The applied voltage increased the total chloride content in cement paste mainly by increasing the free chloride and C-SH bound chloride.