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为了研究不同结构区域混凝土的损伤特性和劣化机理,对宁波某海工码头板梁(大气区)、横梁(潮汐区)和方桩(水下区)等结构区域混凝土外观、力学性能、碳化深度、自由氯离子含量分布、表观氯离子扩散系数、碱含量和钢筋保护层厚度进行检测。研究结果表明,大气区和潮汐区结构混凝土强度状态较好,水下区结构混凝土强度状态较差,混凝土碳化深度和钢筋保护层厚度Dne/Dnd分布规律为大气区>潮汐区>水下区,混凝土表面氯离子浓度、表观氯离子扩散系数(Da)和碱含量分布规律是水下区>潮汐区>大气区,CO2侵蚀作用导致大气区混凝土钢筋保护层劣化,有害介质氯离子与CO2侵蚀共同作用引起潮汐区混凝土钢筋锈蚀和钢筋保护层劣化,有害介质氯离子与盐分渗透进混凝土内部,结构混凝土高浓度碱与氯离子耦合作用加速水下区混凝土钢筋锈蚀速度,导致钢筋保护层劣化。
In order to study the damage characteristics and deterioration mechanism of concrete in different structural regions, the concrete appearance, mechanical properties, depth of carbonation in the structural area of slab beam (atmosphere), cross beam (tidal zone) and square pile (underwater zone) , Free chlorine ion content distribution, apparent chloride ion diffusion coefficient, alkali content and the thickness of the protective layer of reinforced bar. The results show that the strength state of concrete in atmosphere and tidal zone is good, and the strength of concrete in underwater structure is poor. The distribution of Dne / Dnd of carbonation depth and rebar thickness is in the atmosphere> tidal zone> underwater area, The distribution of chloride ion concentration, apparent chloride ion diffusion coefficient (Da) and alkali content of concrete surface is submerged zone> tidal zone> atmospheric zone. The CO2 erosion causes the deterioration of protective layer of reinforced concrete in atmospheric zone, The joint action causes corrosion of reinforcing steel bar and deterioration of protective layer of reinforced concrete in tidal zone. Chloride ions and salt penetrate into the concrete inside the concrete. The coupling effect of high concentration alkali and chloride ion in concrete accelerates the corrosion rate of concrete in underwater area, resulting in deterioration of protective layer.