Corrosion monitoring in infrastructures using ultrasonic wave propogation

Building and subsequent maintenance activities of civil infrastructure are responsible for a large quantity of CO2 emissions in the atmosphere. Extending the life of infrastructure through regular monitoring and retrofitting can reduce environmental damage to a great extent. Inspection, diagnosis and prognosis of damage in installations are imperative for avoiding their catastrophic failures. This paper illustrates the ability ultrasonic guided waves to pick up the signs of corrosion damage in reinforced concrete bars. Various wave propagation modes have been studied. The emphasis is on discovering hidden degradations such as corrosion of bars inside concrete and submerged plated structures. The mode structures and frequencies that are suitable for discovering the damages of interest are identified through a theoretical model. Reinforcing bars embedded in concrete have been corroded to different extents. The bars have been monitored using the theoretically determined frequencies during the progression of corrosion. Destructive tests are carried out at the end of the exposure to correlate to ultrasonic results. It is observed that specific guided wave modes can be created for identifying different types of corrosion. Thus, along with diagnosis the tests can be effective in prognosis of corroded structures