非均匀锈蚀钢筋-混凝土黏结性能试验

Test on bond behavior between non-uniform corroded steel and concrete

为探究非均匀锈蚀对钢筋与混凝土黏结性能的劣化规律,浇筑了8榀钢筋混凝土梁试件,首先通过外加电流引入钢筋锈蚀;钢筋达到设计质量损失率后停止通电,记录混凝土表面锈胀裂缝开展情况;然后对梁试件施加三点弯曲荷载以测试其黏结性能;最后梁试件黏结破坏后,将黏结区锈蚀钢筋取出进行三维扫描测试。试验结果表明:钢筋锈蚀产物体积膨胀引起混凝土保护层产生沿纵向受拉钢筋轴线方向的锈胀裂缝,且混凝土表面最大锈胀裂缝宽度与钢筋质量损失率呈对数关系;锈蚀钢筋表面存在锈坑,随着钢筋质量损失率增加到10.3%,锈坑总长度、总宽度和总深度分别显著增加了68.27、40.21、9.98 mm,即锈坑总长度随钢筋质量损失率的增加变化最为显著。基于试验结果,建立了考虑非均匀锈蚀影响的钢筋与混凝土相对黏结强度退化模型以及质量损失率与混凝土表面最大锈胀裂缝宽度的相关关系模型;并据此提出了基于混凝土表面最大锈胀裂缝宽度的相对黏结强度计算模型,且验证了模型的有效性。

Eight beams of reinforced concrete were prepared to investigate the deterioration law of non-uniform corrosion on the bond performance of steel bar and concrete.First,the corrosion of the steel bar was obtained by applied-current.The electricity was stopped when the specimen reached the designed mass loss rate,and the development of corrosive cracks on the concrete surface was recorded.Then,three-point bending load was applied to the beam specimen to test its bonding performance.Finally,the corroded steel bar in the bonding area was taken out for 3D scanning test after the bond failure of the beam specimen.Test results show that the volume expansion of the corrosion products of the steel bar caused the corrosive cracks in the concrete protective layer along the axis of the longitudinal tensile bar,and the maximum corrosive crack widths on the concrete surface had a logarithmic relationship with the mass loss rate of the steel bar.There were rust pits on the surface of the corroded steel bar,and as the mass loss rate of steel bar increased to 10.3%,the total length,width,and depth of the rust pits increased by 68.27,40.21,and 9.98 mm,respectively,suggesting that the total length of the rust pits had the most significant increase.On the basis of the test results,a relative bond strength degradation model of steel bar and concrete was established in consideration of the influence of non-uniform corrosion.According to the correlation between the mass loss rate and the maximum corrosive crack width on the concrete surface,a calculation model of relative bond strength based on the maximum corrosive crack width on the concrete surface was proposed and verified.