The combination of two types of prevention methods, namely cathodic protection and protective coating, has been used for marine steel structures, ensuring their long-term durability. Regarding the protective coating method, deterioration characteristics including life expectancy have been clarified from the past exposure test results. However, methods of checking the performance of each protective coating method at the time of design, methods of evaluating current protective performance at the time of maintenance and management, and methods of predicting future situations have not yet been established.

Maintenance and management costs remain high and there are not enough technicians, so more efficient methods of maintaining and managing the above social capital urgently need to be developed.

In this theme, we are working on establishing the following methods: a method to check the performance of each protective coating method at the time of design, a method to evaluate the current protective performance at the time of maintenance and management, and a method to predict the future situation.

Investigation (1): We elucidated the deterioration mechanism of the petrolatum coating method and conducted accelerated deterioration tests to establish a method to evaluate the performance of petrolatum material.

Investigation (2): We conducted field studies on the protective coating construction method and corrosion at the boundary of the existing concrete superstructure at Hazaki observation pier.