EACS 2012 – 5 th European Conference on Structural Control Genoa, Italy – 18-20 June 2012 Paper No. # 157 1 * Corresponding author Implementation of Acoustic Emission Sensing for Detecting Corrosion in Prestressed Concrete Mohamed K. ELBATANOUNY*, Jesé MANGUAL, William VELEZ, Paul H. ZIEHL, Fabio MATTA University of South Carolina Department of Civil and Environmental Engineering 300 Main Street, Columbia, SC, USA elbatano@email.sc.edu;mangual@email.sc.edu;velezw@email.sc.edu;ziehl@cec.sc.edu;mattaf@cec.sc.edu ABSTRACT Prestressed concrete bridges are one of the main components of the highway network in the United States and the structural integrity of some of these bridges can be questioned. One of the main reasons for structural degradation is corrosion, especially in coastal areas or areas where de-icing salts are used. This study focuses on early corrosion detection by acoustic emission (AE) sensing in two main structural members: prestressed beams and piles. A set of two prestressed T-beams were cast with a length of 4.98 m and a depth of 380 mm; the beams were prestressed with two 13 mm prestressing strands with a cover of 50 mm. The beams were pre-cracked at mid-span to facilitate the penetration of chlorides to the strands. The corrosion process was simulated by 3-day wet/4-day dry cycling using a 3% NaCl solution. A set of six scaled 1830 x 200 x 90 mm prestressed concrete piles were also cast. The specimens were exposed to 3% NaCl solution simulating the tidal action that occurs at the splash zone. The specimens were continuously monitored using AE sensors. Half-cell potential and linear polarization resistance measurements were taken at constant time intervals to detect the initiation and progression of corrosion and to provide a benchmark to evaluate the acoustic emission data. Preliminary results of this study are presented to discuss the potential of acoustic emission sensing in comparison to electrochemical techniques that are typically more invasive and time consuming. Keywords: Corrosion, acoustic emission, prestressed concrete, non-destructive testing, splash zone. 1 INTRODUCTION Many of the concrete bridges are deteriorating in the United States and elsewhere. Recent studies by the American Society of Civil Engineers (ASCE) show that almost 27% of the nation’s bridges are either structurally deficient or functionally obsolete. While some progress has been made in recent years to reduce the number of deficient and obsolete bridges in rural areas, the number in urban areas is rising. It is estimated that a $17 billion annual investment is needed to substantially improve current bridge conditions. Currently only $10.5 billion is spent annually on the construction and maintenance of bridges [1]. The ASCE report card provides a C grade for the condition of America’s bridges. It is important to develop an improved means for the condition assessment of bridges, thereby improving the prioritization of limited maintenance funding. Corrosion is a main contributor to the deterioration of concrete structures, especially in coastal areas or in areas where de-icing salts are used [2,3]. Determining the extent of corrosion in reinforced or prestressed concrete structures is difficult as access to the reinforcing steel is only