Enhancing the Chloride Adsorption and Durability of Sulfate-Resistant Cement-Based Materials by Controlling the...

Chloride-ion (Cl^-)-induced corrosion of steel bars is a major threat to the durability of marine concrete structures. To address this, a type of calcined CaFeAl-layered double oxide (LDO-CFA) with different calcination temperatures was used to enhanced the Cl^- adsorption, compressive strength, and corrosion resistance of sulphate-resistant Portland cement (SRPC)-based materials. Experimental results demonstrated that LDO-CFA exhibited high Cl^- adsorption capacity in both CPSs and cement-based materials. Specifically, LDO-750-CFA reached 1.98 mmol/g in CPSs-60.1% higher than LDHs-CFA-and followed the Langmuir model, indicating monolayer adsorption. It also reduced the free Cl^- content of SRPC paste to 0.255-0.293% after 28 days, confirming its sustained adsorption over extended curing. Furthermore, LDO-CFA positively influenced the compressive strength at all curing ages. At an optimal dosage of 0.8 wt.%, LDO-750-CFA paste significantly improved the compressive strength, increasing it by 22.1% at 7 days and 15.6% at 28 days compared to the control. Electrochemical analysis confirmed the superior corrosion resistance of the LDO-750-CFA system. The property enhancement originated from LDO-750-CFA's synergistic effects, which included pore refinement, increased tortuosity, Cl^- adsorption by structural memory, a PVP-induced passive film, and PVP-improved dispersion. Overall, this work provides a framework for developing LDO-750-CFA-based composites, paving the way for more durable marine concrete.