Degradation Process and Life Span Estimation of Marine Concrete Structures

本研究在制定约束宽度体积比、CFRP片材配筋、混凝土接缝含盐度假定的基础上，采用高工作性混凝土作为影响因素，对钢筋混凝土受弯构件在盐水喷洒加速环境下的钢筋锈蚀进行监测。主要研究结果如下：(1)目前在盐水喷洒条件下，试件均产生了宽度大于0.2 mm、长度超过数倍的轴向裂纹。虽然Rho_S对裂缝的区分不明显，但在碳纤维片材试件中，裂缝宽度趋于较小。高和易性混凝土试件的裂缝宽度和裂缝长度都有大于素混凝土的趋势(B)从退化试件的弯曲跨度的腐蚀损失率来看，有约束的试件的锈蚀损失率更大。CFRP片材试件的腐蚀损失率相对较小，这是由于CFRP片材表面涂层外的裂纹约束对盐度的遮挡。(C)从矩形波腐蚀监测仪的腐蚀速率老化情况来看，腐蚀速率从轴向裂纹的弥散处(97/7左右)开始增大，之后趋于减小。增加是由于裂纹的扩展，减少是由于腐蚀产物的堵塞。

In this study, in making width volume ratio of confinement, existence of the CFRP sheet reinforcement, placing joint of the concrete including the salinity on the assumption of the macrocell corrosion, use of high workable concrete to be a factor, reinforcement corrosion of the RC flexural member in the salt water sprinkling accelarating environment was monitored. Results got are as follows.(a) The axial crack of width over 0.2mm and over several length has been all generated in specimens under salt water sprinkling at present. Though the difference of the crack by rho_s was not clear, in the CFRP sheet specimen, the crack width tended to be small. Both crack width and length of the high workable concrete specimen tended to be larger than the plain concrete(b) From corrosion loss rate of the bending span of the degraded specimen by AC corrosion monitor, more corrosion loss rate was observed in those specimens with confinement. Corrosion loss rate of the CFRP sheet reinforcement specimen comparatively small, It is due to the shielding of the salinity by the restraint of the crack in addition to the surface coating of the CFRP sheet.(c) Judging from aging of corrosion rate by the rectangular wave corrosion monitor, corrosion rate once increases on the dispersion from the axial cracking (around 97/7) and it tends to decrease afterwards. The increase is due to the crack propergation and the decrease is due to plugging of corrosion product.