RESEARCH ON PREVENTING REINFORCING BAR CORROSION IN CONCRETE STRUCTURES CAUSED BY CHLORIDES IN SEA SAND

1. 防止腐蚀的亚硝酸盐离子/氯离子摩尔比(1)随着混凝土中氯化物含量的增加，摩尔比的阈值也随之增加。(2)与氯化物含量无关的摩尔比为1或更大，可以防止钢筋的腐蚀。(1)当混凝土中存在一小块没有亚硝酸盐离子的区域时，由于大细胞腐蚀，阳极部位的腐蚀会加速。(2)当亚硝酸盐离子分布在混凝土各处且摩尔比大于0.5时，不存在因亚硝酸盐离子浓度不同而加速腐蚀的现象。当亚硝酸盐离子以摩尔比为1或更大的浓度分布在整个混凝土中时，即使浓度不均匀，也能充分抑制钢筋的腐蚀。亚硝酸盐离子的渗透缓蚀剂的低压注入方法，使亚硝酸盐离子渗透混凝土的速度快，范围大。然而，缓蚀剂在潮湿条件下不能渗透太多。钢筋锈蚀修复方法使用亚硝酸盐缓蚀剂的低压注入方法，对于混凝土表面出现微小裂缝的锈蚀钢筋的预防是非常有效和实用的。

1. Nitrite Ion/Chloride Ion Molar Ratio above which Corrosion is Prevented(1) The threshold value of molar ratio increases as the chloride content in concrete increases.(2) Corrosion of reinforcing bar can be prevented with the molar ratio of 1 or more independent of the chloride content.2. Effect of Nonuniform Distribution of Nitrite on Corrosion Prevention(1) Acceleration of corrosion on the anodic sites due to macrocell corrosion is observed when a small zone without nitrite ions exists in the concrete.(2) No corrosion acceleration due to differential nitrite ion concentrations is observed when nitrite ions are distributed throughout the concrete with the molar ratio of 0.5 or more. Corrosion of reinforcing bar is sufficiently inhibited when nitrite ions are distributed throughout the concrete at the concentration of molar ratio of 1 or more, even if the concentrations are not uniform.3. Permeation of Nitrite IonsThe low-pressure injection method of corrosion inhibitor enables nitrite ions to permeate concrete fast and in a wide range. However, corrosion inhibitor cannot permeate much in wet condition.4. Repair Method for Corrosion of Reinforcing BarsThe low-pressure injection method using nitrite corrosion inhibitor can be very effective and practical for corrosion prevention of reinforcing bars in a state of corrosion in which minute cracks are occurring on the surface of concrete.