疲劳荷载和环境腐蚀作用下环氧涂层钢筋混凝土试件的耐久性研究

Durability behaviour of epoxy-coated reinforcing concrete test specimens under fatigue load and environmental attacks

为探讨疲劳荷载和环境对服役配环氧涂层钢筋混凝土桥板耐久性能的影响,设计了配不同环氧涂层钢筋的20根钢筋混凝土试件,分别进行了试件的疲劳加载和盐水腐蚀试验。运用电化学方法对已加载和未加载试件中不同涂层厚度钢筋的腐蚀电位和阻抗进行了测试,并结合不同试件的裂缝分布,进行了钢筋腐蚀电位和阻抗分析。分析结果表明,环氧涂层的强耐腐蚀性能有效防护钢筋;不同厚度的环氧涂层会改变钢筋与混凝土之间的粘结特性,影响钢筋混凝土试件的裂缝开裂形式;钢筋腐蚀电位和试件阻抗图谱反映试件内钢筋的锈蚀程度,加载形式不同会对试件钢筋锈蚀产生不同影响。

In order to study the influence of fatigue load and environment attacks on the durability behaviour of the reinforced concrete （RC） bridge slabs with epoxy-coated reinforcements, 20 RC test specimens containing epoxy-coated reinforcements with different coating thicknesses were designed. 15 test specimens were subjected to the in-service fatigue loads and then all test specimens were subjected to simulated seawater solution attack. Monitoring of open-circuit potential and electrochemical impedance spectroscopy （EIS） were used to evaluate the corrosion behavior of the epoxy-coated and uncoated reinforcing bars in the RC test specimens. Test results show that, epoxy coating can provide effective anti-corrosion protection for reinforcing bars. Bond behavior of the epoxy-coat reinforcing bars may change with the different thickness of coating, resulting in different maximum crack width and crack space under fatigue loads. Thus the open-circuit potential and EIS of the epoxy-coated and uncoated reinforcing bars may be influenced by the fatigue load upper limit and load cycles.