Abstract: With the development of marine infrastructure construction in recent years, the durability requirements of cement-based materials in marine environments have been increasingly raised. Ferroaluminate cement is the "third-generation cement" in China, which has excellent performance of resistance to seawater erosion. The purpose of this study was to explore the mechanical properties and microstructural changes of ferroaluminate cement concrete (FACC) and ordinary Portland cement concrete (OPCC) under the seawater dry-wet cycle, with particular attention to the influence of water-to-cement ratio on the properties. The physical and mechanical properties such as mass loss rate, relative dynamic elastic modulus and cube compressive strength of FACC and OPCC were compared and analyzed by experiments, and the microstructure was analyzed by scanning electron microscope and mercury intrusion method. The results show that during the seawater dry-wet cycle, FACC has a lower mass loss rate, and the relative dynamic elastic modulus of FACC increases at the beginning of the seawater dry-wet cycle and then tends to be stable, while relative dynamic elastic modulus of OPCC shows a significant decrease in the later stage of the seawater dry-wet cycle. In terms of compressive strength, FACC increases after seawater dry-wet cycle, while OPCC decreases. Overall, FACC demonstrates superior durability and stronger resistance to seawater erosion compared to OPCC. Microscopic analysis reveals that FACC has lower porosity and finer pore structure, which contributes to improve its durability.

Key words: ferroaluminate cement, seawater dry-wet cycle, mass loss rate, relative elastic modulus, compressive strength, microscopic property