混凝土梁电化学修复后的耐久性能及力学特征

电化学修复技术可对耐久性劣化的混凝土结构进行耐久性提升,然而也会引起黏结性能降低、混凝土孔隙结构改变、钢筋氢脆等负面效应,进而影响构件整体的服役性能.为探明电化学除氯和双向电迁处理后混凝土梁的耐久性能及力学性能,本文结合氯离子含量梯度变化和弱极化曲线等对比分析了电化学修复后梁的抗腐蚀性能,结合荷载挠度曲线、钢筋与混凝土应变、裂缝分布等对比分析了静力力学性能.研究结果表明:电化学修复能有效去除钢筋表面氯离子,使钢筋恢复钝化,但钢筋笼内氯离子迁移效率相对较低；通电参数选取较小时电化学修复不影响混凝土梁的刚度和承载能力,但通电量较大时承载能力减小,延性退化较为明显.基于试验结果,本文建议电化学修复采用的通电参数需综合考虑耐久性提升效果及对力学性能损伤作用,以满足结构耐久性和安全性的要求.

Durability enhancement and mechanical properties of concrete beams after electrochemical rehabilitation

Electrochemical rehabilitation technology is an effective method to improve the durability of chloride ion contaminated concrete structures. However, negative effects such as reduction of bonding performance, pore structure changes of concrete, and hydrogen embrittlement of steel bar are induced simultaneously, leading to the service performance deterioration of the monolithic component. In order to explore the durability enhancement and mechanical properties of concrete beams after electrochemical chloride extraction and bidirectional electromigration, the corrosion resistance properties of concrete beam after electrochemical rehabilitation were analyzed by combining chloride ion content gradient and potentiodynamic polarization curves, and the static mechanical properties were investigated through load-deflection curves, strain of steel and concrete, and crack distribution of concrete. Results show that electrochemical rehabilitation could effectively remove the surface chloride ions of steel bar and restore the passivation of steel bar, but the extraction of the chloride ions inside steel cage was difficult. When small electrification parameters were selected, electrochemical rehabilitation hardly affected the stiffness and load bearing capacity of the beam, while the bearing capacity decreased when the amount of electricity increased, and the ductility degradation became more obvious. In order to meet the requirements of durability and structural safety, it is suggested that effects of durability enhancement and impacts on mechanical properties deterioration should be comprehensively taken into consideration when selecting electrification parameters for electrochemical rehabilitation.