Chloride Adsorption Capacity of Monocarbonate: The Importance of Iron Doping

Resistance to chloride penetration is a concerned durability issue to ordinary Portland cement (OPC) based materials used in the marine environment. Monocarbonate has become an increasingly common hydration product observed in OPC-based materials and plays an important role in chloride adsorption. The Portland cement used in ocean engineering has a notably higher C(4)AF content than C(3)A, and C(4)AF has become a particularly important aluminate phase in it. However, few studies have focused on the discrepancy in the chloride-binding capabilities of C(3)A hydrates and C(4)AF hydrates. The objective of this paper is to study the discrepancies in chloride adsorption between undoped and Fe-doped monocarbonates. The results suggest that the Fe-doped C-4(A,F)(C) over barH(11) exhibits superior chloride adsorption than undoped C(4)A (C) over barH(11) because the doping of Fe weakens the restriction of the surrounding hydrogen bond connected to CO32- in its interlayer. A pseudo-second-order kinetic model is more suitable for the characterization of the chloride adsorption process on monocarbonates. Freundlich isotherm is favorable to fit the experimental data of chloride adsorption by the monocarbonate. This study holds great promise for improving the chloride penetration resistance of Portland cement.

Automated summary

This study focuses on the discrepancies in chloride adsorption between undoped and Fe-doped monocarbonates. The results indicate that Fe-doped C-4(A,F)(C)H(11) exhibits superior chloride adsorption compared to undoped C(4)A(C)H(11) due to the weakening of hydrogen bond restrictions. A pseudo-second-order kinetic model and Freundlich isotherm are suitable for characterizing the chloride adsorption process on monocarbonates. This study holds great promise for improving the chloride penetration resistance of Portland cement.