Coupling effect of the connected pores and pore solution on chloride ion migration in cement-based materials

Abstract

In this study, a new method for determining the connected pore porosity, tortuosity and constrictivity was developed based on AC impedance tests. The effects of the pore factor χ1, pore solution factor χ2, pore–pore solution factor χ3 and coupling factor χ on the non-steady state chloride ion migration coefficient (Dm) were evaluated. The results indicated that χ1, χ2, χ3 and any single parameter did not have good correlations with Dm, and χ had an excellent linear correlation with Dm. This confirms that the coupling effect of the pores, the pore solution and their interaction control the chloride ion migration process. The contributions of χ1, χ2 and χ3 to Dm accounted for 54.44%, 13.05%, and 31.27%, respectively. Therefore, the migration of chloride ions can be controlled to a large extent by reducing χ1 and χ3, which can be obtained through a reduction in the connected porosity and the accompanying reduction in δ. This means that the connected pores play a decisive role in controlling the migration of chloride ions in cement-based materials, whose conductivity can be used for quickly determining the extreme value of the chlorine-related durability.