Chloride‐Binding Capacity of Portland Cement Paste Blended with Synthesized CA 2 (CaO·2Al 2 O 3 )

A chloride‐binding capacity is the major factor to mitigate the ingress of chloride into concrete. This paper presents the chloride‐binding capacity of Portland cement paste containing synthesized CA 2 (CaO·2Al 2 O 3 ). The CA 2 was synthesized in the high‐temperature furnace and characterized by X‐ray diffraction for inspecting the purity. The synthesized CA 2 was substituted for Portland cement by 0%, 5%, and 10% by weight, and the NaCl solution was used as an internal chloride, which is assumed as a total chloride. The chloride‐binding capacity of cement paste was calculated from a water‐soluble chloride extraction method by the application of the Langmuir isotherm equation. And the hydration products were analyzed using X‐ray diffraction and thermogravimetric analysis. We demonstrate that the CA 2 increases an AFm phase in the Portland cement system, and the incorporation of CA 2 consequently enhances the chloride‐binding capacity of cement paste samples.