锈蚀钢筋与混凝土间黏结性能试验

为研究锈蚀对钢筋与混凝土间黏结性能的影响,制作20个中心拉拔试件.通过电化学加速锈蚀得到理论锈蚀率为0%、0.5%、1%、2%、5%的拉拔试件,完成了不同锈蚀率下钢筋与混凝土的拉拔试验.从钢筋几何外形特征与混凝土强度在锈蚀过程中变化的角度分析了锈蚀率对极限黏结强度的影响,以割线刚度的方法定量研究了锈蚀率对黏结刚度的影响.阐述了锈胀裂纹、黏结刚度及试件破坏模式随锈蚀率变化的规律.试验结果表明:随着锈蚀率增大,钢筋与混凝土间的黏结强度、黏结刚度呈现先增大后减小趋势.黏结刚度的退化与锈胀裂纹的出现具有一定相关性.通过整理国内外学者黏结强度退化数据,得到了两段式黏结强度退化试验模型及一定程度上可供工程参考的黏结强度退化保守模型.最后,基于两段式黏结-滑移模型得到了不同锈蚀率下钢筋与混凝土间黏结-滑移本构模型.

Experimental study on bond performance between corroded reinforced bar and concrete

To investigate the influence of corrosion on the bond performance between steel bar and concrete, twenty central pull-out test specimens were cast. Pull-out tests were conducted to study the bond behavior between concrete and steel bar corroded using current accelerate method with the expected mass loss of 0%, 0.5%, 1%, 2%, 5%. The variation of the bond performance between steel bar and concrete caused by steel bar corrosion was explained according to the change of steel bar geometrical characters and concrete strength in the whole corrosion process and the influence of corrosion rate on bond stiffness was studied by method of secant bond stiffness. The variation law of cracking due to corrosion expansion, bond stiffness and failure mode with various corrosion levels were studied. The test results show that bond strength and bond stiffness increase at the beginning and then decrease with the corrosion increasing. The degeneration of bond stiffness related to the appearance of cracking due to corrosion expansion. A simplified two-stage test model and conservative model partly available for reference to similar projects were proposed. A bond-slip constitutive relation with different corrosion rates was proposed based on two-stage model.