Longitudinal Guided Waves for Monitoring Chloride Corrosion in Reinforcing Bars in Concrete

Abstract

Corrosion of reinforcing steel in concrete is one of the major durability problems faced by civil engineers as they maintain an aging infrastructure. The problem accelerates since steel is embedded inside concrete. If it remains unnoticed inside concrete, it further accelerates and can cause loss of life and property. This article discusses a nonintrusive corrosion monitoring technique for early detection of damages in steel embedded in concrete. Corrosion manifests itself in debond and pitting steel bars. Guided ultrasonic waves offer a potentially attractive solution for this problem. But it is imperative to excite the right mode for detection of a particular type of corrosion. In the present work, longitudinal guided ultrasonic waves have been utilized to monitor notch and debond defects in steel bars in concrete simulating pitting and delamination phenomena caused by corrosion. Two ultrasonic techniques of pulse transmission and pulse echo were used to monitor the healthy and damaged specimens. The developed methodology is successfully applied for real time monitoring of RC beam specimens undergoing accelerated chloride corrosion. The ultrasonic signals effectively relate to the state of reinforcing bars.

Monitoring freshly poured concrete using ultrasonic waves guided through reinforcing bars

“…The authors have reported that specific ultrasonic guided wave modes are effective in monitoring core and surface areas of waveguides [32]. By studying the modal displacement and energy distribution functions, specific modes can be identified that are sensitive to surface changes [33,34]. The authors used signals from specific modes to identify different types of corrosion of steel bars and correlate them with parameters such as mass loss, residual strength and pull out strength [33].…”

“…By studying the modal displacement and energy distribution functions, specific modes can be identified that are sensitive to surface changes [33,34]. The authors used signals from specific modes to identify different types of corrosion of steel bars and correlate them with parameters such as mass loss, residual strength and pull out strength [33]. In this investigation, the modal excitation technique is applied to monitor the development of bond between steel and concrete.…”

Chloride penetration monitoring in reinforced concrete structure using carbon nanotube/cement composite

“…Measuring changes in the electrical characteristics of corroded reinforcements is one of the non-destructive monitoring methods [9][10][11][12]. The electrical conductivity and impedance of steel is changed by corrosion, and by measuring these electrical characteristics, the corrosion of the reinforcement can be monitored [9,10].…”

Assessing Corrosion Damage and Corrosion Progression in Multistrand Anchor Systems in Use at Corps Projects

“…This product is the result of efforts of the South West Research Institute in Texas. Sharma and Mukherjee (2010) describe accelerated corrosion testing of rods and using guided waves tuned for high cross-sectional sensitivity. For chloride-type defects with caustic pitting and surface distortion, the decrease in surface profile sensitivity increases the sensitivity to local bar topography (Sharma and Mukherjee 2010).…”