Concrete Corrosion Assessment

About

Reference #: 01039 The University of South Carolina is offering licensing opportunities for a non-intrusive technique to detect, monitor, and quantify corrosion damage in post-tensioned concrete construction, either in combination with or in the absence of regular electrochemical techniques. Invention Description: The subject invention is an algorithm(s) for the detection and assessment of corrosion damage in reinforced concrete structures and systems, particularly in those  reinforced with post-tensioned (PT) strands. It uses commercially available sensors mounted to the post-tensioning duct (external post-tensioning) or to the concrete surface in the case of embedded ducts (internal post-tensioning). Potential Applications: Monitoring of buildings, bridges, dams, nuclear containment structures, and other structures both for assessment of safety and for asset management Advantages and Benefits: Does not require access to the post-tensioning being monitored Detects and quantifies damage in PT structures due to corrosion in real time May detect the corrosion process prior to conventional electrochemical measurements and can be effectively used where there is no provision for electrochemical measurements Background: Visual inspection of prestressed and post-tensioned bridges is difficult and often lacks a provision for electrochemical measurements to determine the corrosion levels in the strands. As such, a structural health monitoring (SHM) method is needed to evaluate the damage in the strands. Surface based sensing is one potential approach. Research has shown that surface mounted sensors can be effectively used to detect corrosion in concrete structures. However, there is always a hindrance due to thick concrete cover and the use of plastic ducts. Appropriate data treatment must  be utilized to minimize noise and retain corrosion data in realistic applications. Previous research has largely focused on corrosion detection of passive reinforcement, and some studies have focused on prestressing applications. This invention detects corrosion in actively stressed strands in a setting that is representative of both internal and external bonded post-tensioning. Experimental Validation: Corrosion was induced in both internal and external PT specimens. The corrosion process was monitored by half-cell potential (HCP) measurements and surface mounted sensors. Results show that the surface mounted sensors have the ability to detect and quantify corrosion initiation, propagation, and cracking in the PT specimens with the same accuracy as HCP measurements. Further, analysis of the data shows that the damage in the PT specimens can be categorized according to the rate of ongoing corrosion damage.