海洋生物附着对混凝土结构耐久性能影响

为研究海洋生物对混凝土结构的影响机理，分别对海洋动物、植物以及微生物3种类型的海洋生物进行分析，重点讨论3种生物对混凝土结构的腐蚀机理和增强机理，并对其利用和防治进行了详细论述。通过某码头混凝土桩的现场长期暴露试验，研究混凝土内部的氯离子浓度、混凝土电阻率及钢筋电位的分布规律。结果表明，浪溅区的表面氯离子含量低于潮汐区，而混凝土氯离子扩散系数较为接近。贝类生物的聚集作用对混凝土抗氯离子性能具有正负效应:一方面，贝类覆盖区混凝土的表面氯离子含量较低，表明贝类的存在有利于降低混凝土表面氯离子的聚集，在混凝土表面起到物理保护作用，一定程度上有利于阻止氯离子的入侵；另一方面，贝类覆盖区混凝土内氯离子扩散系数大于光滑表面区，贝类的存在可能导致混凝土本体发生变化，削弱了混凝土自身的抗氯离子侵蚀能力，加快了氯离子在混凝土内部的传输。有贝类聚集时，混凝土表面电阻最低，且混凝土内部钢筋的腐蚀电位较负，表明该区域混凝土内部钢筋的腐蚀风险最高，该海域贝类存在可能对混凝土的耐久性能造成不利影响。

Influence of marine organisms adhesion on durability of concrete structures

To investigate the influence mechanism of marine organisms on concrete structures, marine organisms were introduced in three categories: marine animals, plants and microorganisms. The corrosion and enhancement mechanisms of marine organisms on concrete structures were analyzed in three categories. Also, the ways of prevention and utilization of the marine organisms were discussed in detail. Through the long term field exposure test of the wharf piles, the distributions of the chloride concentration, concrete resistivity and steel potential in concrete were obtained. The results show that the chloride ion contents at the concrete surface in the splash zone are lower than those of the tidal zone. However, the chloride ion diffusion coefficients of the concrete are fairly close in both of the splash zone and tidal zone. The accumulation of shellfish has both positive and negative effects on the chloride resistance of concrete. On one hand, the chloride ion contents at the surface of concrete covered with shellfish are lower than those without the coverage of shellfish, which indicates that the presence of shellfish might help to reduce the concentration of chloride ions on concrete surface. Shellfish exhibits a physical protection mechanism for the concrete surface, which is beneficial for the prevention of chloride ion ingression into concrete to some extent. On the other hand, the chloride diffusion coefficients of concrete covered by the shellfish are larger than those with the smooth concrete surface. Theoretically speaking, the presence of shellfish may lead to the chemical change of concrete, weaken the chloride resistance of concrete, and eventually accelerate the chloride ion transport in concrete. Additionally, the concrete covered by the shellfish presents the lowest surface resistance, and the reinforcing steel bars embedded in it indicates a relatively negative corrosion potential. Finally, the results demonstrate that the steel reinforcement in the concrete covered by shellfish shows the highest corrosion risk. The existence of shellfish may adversely affect the durability of concrete structures.