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In the vast ocean environment, the application of traditional silicate cement faces severe challenges. It is easily eroded by seawater, leading to rapid deterioration of concrete structures, thereby seriously affecting the durability of marine engineering structures. Therefore, the evaluation of seawater erosion resistance of cement used in marine construction becomes a key link to ensure the safety of marine engineering and extend its service life.
The ocean environment is complex and ever-changing. Cement for marine construction not only has to withstand the severe scouring of waves and the periodic action of tides but also needs to resist biological erosion from shellfish, algae, and microorganisms, and counter the chemical attack from corrosive ions in seawater such as Cl-, Mg2+, SO42-. Historical data shows that many early harbor projects experienced severe damage far below their design life due to insufficient consideration of the cement's seawater erosion resistance performance. This not only caused huge economic losses but also highlighted the necessity and urgency of evaluating the seawater erosion resistance of cement used in marine construction.
The abundant corrosive ions in seawater, especially Cl-, Mg2+, SO42-, pose a major threat to cement used in marine construction. Cl- reaches the interior of the concrete through permeation, accelerating the corrosion of steel reinforcement and weakening the structural strength. Mg2+ reacts with hydration products, destroying the alkaline environment of the cement system, triggering instability in calcium silicate hydrate and calcium aluminate hydrate, further reducing the concrete strength. On the other hand, SO42- creates expansive substances that cause concrete cracking, accelerating overall structural damage. A thorough understanding of these corrosion mechanisms is crucial for developing effective strategies to evaluate the seawater erosion resistance of cement used in marine construction.
To tackle these challenges, China has established multiple evaluation systems for cement used in marine construction against seawater erosion. According to standards such as GB/T 38140-2019, the compressive strength retention rate K of cement mortar is evaluated by simulating the wet-dry cycles in a marine environment, providing a direct reflection of its seawater erosion resistance. In addition, standards such as GB/T 39712-2020 and GB/T 42272-2022 include evaluation indices such as the seawater erosion resistance coefficient K and chloride ion diffusion coefficient, which comprehensively assess the durability of cement used in marine construction from different dimensions. The implementation of these evaluation methods provides scientific grounds for material selection in marine engineering and lays a solid foundation for enhancing the overall durability of marine engineering structures.
In summary, the evaluation of seawater erosion resistance of cement used in marine construction is a critical measure to ensure the safety of marine engineering and to extend its service life. Through in-depth research on erosion mechanisms and the improvement of evaluation systems, we can provide more reliable and durable building materials for marine engineering construction, supporting the robust development of China's marine industry.
