电化学修复后钢筋混凝土黏结性能演变规律

Evolutionary regularity of bond property for reinforced concrete after electrochemical rehabilitation

  • 摘要: 针对电化学修复技术导致修复后结构内钢筋混凝土黏结性能退化问题,通过中心拉拔实验获取电化学修复后钢筋混凝土黏结滑移曲线,研究电化学修复参数(电流密度和通电时间)对钢筋混凝土黏结性能的影响规律,通过实验结果进行模型参数分析,建立基于电流密度和通电时间两个控制变量的黏结强度劣化模型。研究结果表明:电通量较小的情况下,钢筋混凝土黏结性能损失较小;不控制通电参数的电化学修复技术导致黏结强度下降明显,采用5 A·m–2的电流开展28 d的恒电流通电,试件的最大黏结力损失量高达56.9%;本文提出的劣化模型可以定量表征电化学修复后试件黏结强度折减情况,模型的数值模拟结果与本文及其他文献的实验结果均有较好的一致性,相关系数分别为0.9606和0.9745。

     

    Abstract: Reinforcement corrosion, due to the presence of chloride ions, is a major cause of the degradation of reinforced concrete structures. Nowadays, electrochemical rehabilitation (ER) is becoming a common technique for repairing reinforced structures. Due to the transmission properties of the micro-pores in concrete, chloride ions can be transferred to the outside of the concrete through the pores under the driven force of electric field. Compared with other conventional technologies, ER presents many advantages, such as high efficiency and little influence on the environment and surroundings. However, previous studies indicate that ER exhibits negative effect on the interfacial bonding properties of steel concrete. As the main influence factor for ER, varying current densities may consequently change the bond loss between steel and concrete. In addition, large current density significantly reduces interfacial bond. However, current studies lack relevant quantitative research results and fail to propose an effective method to solve the problem after electrochemical repair since aiming at electrochemical rehabilitation will most likely result in the bond deterioration of reinforced concrete. In this study, the bond-slip curves were obtained through central pull-out specimens after ER with various electrochemical parameters, and the relationship between the electrochemical parameters (current density and conduction time) and the bond behaviors were investigated. Finally, a degradation model of bond strength considering the influences of the two parameters mentioned was established. Results show that the bond strength decreases significantly with high current density and long conduction time. Using a current density of 5 A·m–2, reduction of the max bond force increased up to 22.6% and 56.9% under a conduction time of 15 and 28 d, respectively. The proposed model can be used to quantitatively characterize the reduction of bond strength after electrochemical rehabilitation. Good consistency of results was observed after comparing the evaluated results with that of the experiment.

     

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