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

(1)在相同的阳极电流密度下，由于鞘层的存在，后张法预应力筋的电位位移要小于预张法。(2)对具有自身腐蚀缺陷的钢护套进行阴极保护时，部分电流通过缺陷集中到PC肌腱内部的一部分。然而，这种集中发生在缺陷下的有限区域内，可以认为是有益的现象，可以避免缺陷附近PC肌腱的腐蚀。(3)对有空隙的钢护套进行阴极保护时，空隙下电位位移在预应力筋内增大，在钢护套内减小。通过利用这一现象，有可能提出一种非破坏性技术，以便研究鞘中的空气空洞。

(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.