STUDY ON CONCRETE DURABILITY OF DIFFERENCE STRUCTURAL REGIONS UNDER MARINE ENVIRONMENT
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摘要: 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。Abstract: In order to study the damage characteristics and deterioration mechanism of concrete in difference structural regions, the appearance, mechanical properties, carbonation depth, distribution of free chloride content, apparent chloride ion diffusion coefficient, alkali content and the cover thickness of concrete for plate girder(atmosphere zone), cross beam(tidal zone) and square pile(underwater zone), at the typical region of a marine dock in Ningbo, were tested.The test data show that the structural concrete in the atmosphere and tidal zone have a better compressive strength state, while concrete in underwater zone has a poor compressive strength state, the carbonation depth and Dne/Dnd of the cover thickness are decreased from upper part to lower part, atmosphere zonetidal zoneunderwater zone, the distribution law of free chloride content, apparent chloride diffusion coefficient(Da) and alkali content of concrete are underwater zone tidal zoneatmosphere zone.The conclusions are drawn that CO2 of erosion action at atmosphere zone results in deterioration of the cover thickness, the combined action of harmful chloride ion and CO2 erosion lead to steel corrosion and deterioration of cover thickness at the tidal zone, due to the chloride ion and salt permeate into concrete of underwater zone, the coupling effect of chloride ion and high salt concentration accelerate the deterioration of cover thickness at the underwater zone.
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Key words:
- marine environment /
- structural region /
- durability /
- research
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