Maintenance and Repair System by Cathodic Protection for Post-tension PC Structures under Marine Environment

(1)In在阳极电流密度相同的情况下，由于鞘层的存在，后张法预应力混凝土筋的电位漂移小于先张法。（2）当对由于自身腐蚀而具有缺陷的钢护套施加阴极保护时，部分电流流过缺陷并集中到PC筋内部的一部分。然而，这种集中发生在缺陷下方的有限区域，可以被认为是有益的现象，以避免在缺陷附近的PC筋的腐蚀。（3）当对内部有空气空隙的钢护层施加阴极保护时，空隙下的电位移动在预应力钢束中增大，而在护层中减小。通过利用这种现象，有可能提出一种非破坏性的技术，以研究在护套中的空气空隙。

(1)In the same current density at the anode, the potential shift of PC tendon in post-tensioned method would be less than that of pre-tensioned method, due to the existence of the sheath.(2)When the cathodic protection is applied to the steel sheath having the defect due to the corrosion itself, some current flows through the defect and concentrates to a part of inside PC tendon. However, this concentration, which occurs in limited area under the defect, can be considered as profitable phenomenon to avoid the corrosion of PC tendons in the vicinity of the defect.(3)When the cathodic protection is applied to the steel sheath having the air void inside of it, potential shifts under the void are increasing in PC tendon and decreasing in the sheath. By making use of this phenomenon, it may be possible to propose a non-destructive technique in order to investigate the air-void in the sheath.