【作者】 王一琛； 陈正；

【Author】 WANG Yichen;CHEN Zheng;State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures, School of Civil Engineering and Architecture, Guangxi University;

【机构】 广西大学土木建筑工程学院特色金属材料与组合结构全寿命安全国家重点实验室；

【摘要】 钢筋锈蚀是导致钢筋混凝土结构劣化的主要原因之一,海水中的腐蚀性离子通过破坏钢筋钝化膜来引起锈蚀。传统研究主要考虑了氯离子对钢筋锈蚀的影响,而忽略了硫酸盐对钢筋钝化膜的破坏作用,导致难以揭示混凝土中钢筋钝化膜的去钝化机理。本研究基于电化学方法揭示了硫酸盐对钢筋在模拟混凝土孔隙液中电化学行为的影响,并确定了硫酸盐诱导钢筋钝化膜破坏的临界浓度;并利用XPS测试证明硫酸根离子会减小钢筋钝化膜的厚度,并降低外层的Fe³⁺/Fe²⁺;最后基于第一性原理的密度泛函理论研究了SO₄^2-和α-Fe₂O₃ （001）钝化膜表面的相互作用,结果表明,SO₄^2-的吸附促进了表面空位的形成和扩散,并增强了后续SO₄^2-的吸附,从而在原子层面揭示了硫酸盐导致混凝土中钢筋钝化膜破坏的机理。更多还原

【Abstract】 Corrosion of steel reinforcement is one of the most significant degradation problems in reinforced concrete structures, and corrosive ions in seawater induce steel bar corrosion by breaking passive film. Previous studies have focused on the effect of chloride ions on rebar corrosion but neglected the breakdown effect of sulphate on the passive film of rebar. Therefore, the present study revealed the impact of sulphate on the electrochemical behavior of rebar in the simulated concrete pore solutions based on electrochemical methods, and the critical sulphate concentration of sulphate-induced damage to the passive film of rebar was determined.Moreover, XPS investigation revealed that the presence of sulphate ions reduced the thickness of the rebar passive film and the Fe³⁺/Fe²⁺ ratio in the outer layer. Finally, the interactions of SO₄^2-with the α-Fe₂O₃（001） surface interactions were investigated using the density functional theory, and the adsorption of SO₄^2-promoted the vacancy formation and increase, and enhanced the subsequent adsorption of SO₄^2-. Combining the experimental results and DFT simulation, the mechanism of sulphate-induced damage to the passive film of rebar in concrete at the atomic level was revealed.更多还原