<p>The most prolific cause of damage to existing concrete infrastructure is caused by the corrosion of internal prestressed steel strands in reinforced concrete. Steel strand corrosion simultaneously causes an appreciable change in total volume and reduction in steel cross-sectional area. The increase in volume causes internal pressure buildup, which leads to concrete surface cracking and structure decommission. The loss of steel causes the concrete to lose strength, increasing the probability of structural failure. Surface cracking further exposes the rebar to air, which increases the rate of corrosion. It is imperative for the safety of citizens and tax dollar money to effectively monitor and prevent reinforced concrete corrosion. Reinforced concrete corrosion can be monitored by the acoustic emissions produced by transient mechanical waves of corrosion and damage events. This study aims to use 3D-printed one-way valves to relieve the corrosion-induced internal pressure on concrete structures. This valve is designed in such a way that it can be simply installed to existing structures to increase corrosion resistance in the concrete structure and extend the service life. The valves were designed with a passive rust filter which consisted of a series of metal meshes. The filters prevent the valves from being stuck into an open position, therefore preventing any air from coming into contact with the concrete despite the corrosive state of the steel rebar. The valves are also built-in modules to allow for the easy addition of redundancies. The impressed current technique is a common technique used to rapidly corrode reinforced concrete samples. To corrode the concrete samples, current was passed through the internal steel strand and copper mesh. A ponded salt solution served as the electrolyte. This study investigated the use of an Internet-of-Things device to continuously monitor corrosion in steel-reinforced concrete samples in order to determine the effectiveness of the designed valves. The IoT device monitored acoustic emissions, obtained through several sets of sensors on each sample, to also determine the corrosion stage of reinforced concrete. Pressure testing revealed that the designed valves were robust against backflow and cracked at a very low pressure. It was ideal that the valves cracked at a lower pressure so as to release pressure constantly. Additionally, the backflow resistance prevented air from penetrating the concrete cover and further corroding the steel strand. This type of valve will prevent reinforced concrete surface cracking and extend the service life of concrete structures by releasing internal pressure build-up without allowing foreign materials to further corrode the steel reinforcement.</p>

Corrosion Monitoring and Mitigation in Reinforced Concrete Structures Using Novel 3d-Printed Valves and Internet-of-Things Approach

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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