腐蚀环境中既有裂缝对钢筋混凝土结构耐久性影响规律研究

Study on the influence of existing cracks on durability of concrete structure in corrosive environment

钢筋混凝土结构在施工阶段不可避免产生裂缝,而在腐蚀环境中,腐蚀因子通过混凝土既有裂缝进入混凝土内部,导致混凝土结构内部钢筋锈蚀,使得结构的可靠性和耐久性收到极大的影响,急需一种解决方法.本文主要研究在腐蚀环境中,氯离子在损伤混凝土中的渗透性能,分析浸渍于腐蚀环境中的混凝土结构劣化机制,通过试验模拟追踪钢筋的锈蚀形态,分析钢筋的锈蚀机理,进一步分析锈蚀钢筋所诱发的钢筋混凝土结构锈裂行为,对锈蚀的劣化规律进行分析研究,并建立预测模型.结果表明:初始裂缝大于80μm时,氯离子在混凝土内部的渗透性能得到明显的提高,保护层失去作用.本研究为腐蚀环境中存在既有裂缝的钢筋混凝土结构的运营维护提出合理、及时的指导建议,以有效避免因钢筋进一步锈蚀带来的混凝土表面胀裂、脱落、露筋、锈斑等次生结构损坏,从而实现延长钢筋混凝土结构的使用寿命.

Reinforced concrete structures inevitably develop cracks during the construction stage.In a corrosive environment,corrosion agents penetrate the concrete through the existing cracks,leading to the corrosion of the steel reinforcement within the concrete.This significantly impacts the reliability and durability of the structure,which requires a solutions to resolve the problem.This study primarily investigated the permeability of chloride ions in damaged concrete in a corrosive environment.The degradation mechanisms of concrete structures immersed in a corrosive environment was analyzed.The corrosion patterns of steel reinforcement were simulated and tracked through experiments,and the corrosion mechanisms of the steel reinforcement were analyzed.Furthermore,the cracking behavior induced by corroded steel reinforcement in concrete structures was examined,and the degradation patterns of corrosion was studied.Predictive models was established.The results indicate that when initial cracks exceeded 80μm,the permeability of chloride ions within the concrete significantly increased,which rendering the protective layer ineffective.Through this research,reasonable and timely maintenance guidance can be provided for the operation of reinforced concrete structures with existing cracks in corrosive environments.This helps effectively prevent secondary structural damage such as surface expansion,spalling,exposure of reinforcement,and rust stains caused by further corrosion of the steel reinforcement,ultimately extending the service life of reinforced concrete structures.