Evaluation of Cathodic Protection Field Test with Daikeiji River Bridge on Hokuriku Expressway
By M. Nomura, Y. Maeda, K. Ishimura and T. Hira
Concrete Journal, Vol.37, No.12, Dec. 1999
- Synopsis
- In 1989 the Hokuriku expressway's Daikeiji River Bridge was given cathodic protection as a countermeasure for salt-induced corrosion. This was the first such case in Japan. In the nine years that have passed since cathodic protection was applied, corrosion of the steel reinforcements in the concrete has not progressed in spite of an environment with an amount of chloride much greater than 1.2 kg/m3, the amount above which corrosion is presumed to be initiated. In addition, it is thought that effective conditions for corrosion protection have been maintained for nine years because the specified depolarization has been maintained at 100 mV. As for the evaluation of the performance of anode materials, titanium anodes, which were used in the impressed current cathodic protection system, were found to have no corrosion at all. Therefore it is presumed that the bridge's life span, initially estimated to be 40 years, will be attained. As for zinc sacrificial nodes in the galvanic cathodic protection system, they last approximately 7 years, although the consumption rate of the anodes differs depending on the steel density inside of the concrete and on the corrosive environment.
- Keywords:
- sait-induced corrosion, cathodic protection
