氯盐干湿循环作用下CFRP混凝土界面黏结性能研究

为了考察碳纤维复合材料(carbon fiber reinforced polymer, CFRP)与混凝土结构在氯盐干湿循环作用下界面黏结强度，开展不同干湿循环周期下混凝土的弹性模量、抗压强度和CFRP混凝土单剪试件界面黏结性能的腐蚀劣化试验研究。通过模拟氯盐的干湿循环作用和自主设计的单剪试验稳定装置，对混凝土基体的腐蚀劣化性能和界面的有效黏结长度进行研究，基于Popovics方程分别对不同腐蚀周期的界面黏结应力-滑移关系和界面断裂能进行研究。在此基础上，分析干湿循环作用下CFRP-混凝土界面黏结强度的劣化机理，并建立界面的时变黏结强度计算模型。结果表明，随着干湿循环周期的增长混凝土基体的弹性模量整体变化不大，而抗压强度则呈现出先增大后减小的趋势，最终腐蚀120 d后较未腐蚀混凝土抗压强度降11.2%；界面的有效黏结长度从未腐蚀的120 mm降低到腐蚀120 d后的72 mm，界面的断裂能也大幅下降。基于Popovics方程得到的腐蚀环境下CFRP混凝土界面黏结应力-滑移关系可揭示界面黏结强度劣化机理，建立的界面时变黏结强度模型有效，可应用于不同干湿循环作用下CFRP混凝土界面黏结强度的计算。

Bond behavior of CFRP-concrete interface in chlorine salt solution with wet-dry cycles

To investigate the interfacial bond strength of Carbon Fiber Reinforced Polymer (CFRP) and concrete structures in chlorine salt solution with wet-dry cycles, experiments on the corrosion degradation performance of CFRP-concrete specimens with wet-dry cycles, including compressive strength, elastic modulus of concrete, and bond performance was conducted. A stable single-shear testing device was designed to control the specimens in the tests. By simulating the wet-dry cycles with chlorine salt solution, the time-dependent characteristics including the mechanical properties of the concrete substrate and the effective bond length were studied. The interfacial bond-slip relationship and the interfacial fracture energy in different corrosion duration were analyzed on the basis of the Popovics equation. Meanwhile, the degradation mechanism of the interfacial bond strength of the CFRP-concrete interface was revealed, and a formula for the time-dependent bond strength was proposed. The results show that the elastic modulus of concrete does not change much along with the wet-dry cycles, while the compressive strength shows a trend of first increasing and then decreasing, and finally decreasing by 11.2%. The effective length decreased from 120 mm to 72 mm in 120 days and the performance of interfacial fracture energy shows a significant reduction. This indicates that the mechanism of the bond-slip relationship in the CFRP-concrete interface based on the Popovics equation can reveal the deterioration mechanism of interfacial bond strength under the corrosion environment, and the proposed time-dependent interface bond strength model is effective and can be widely used in calculating the interfacial bond strength of the CFRP-concrete under wet-dry cycles.