STEEL REINFORCEMENT CORROSION DETECTION WITH COAXIAL CABLE SENSORS Iana Muchaidze a , David Pommerenke b , and Genda Chen a a Dept. of Civil, Architectural, and Environmental Engineering, Missouri Univ. of Science and Technology/Rolla, MO, 65401-0030, U.S.A b Dept. of Electrical and Computer Engineering, Missouri Univ. of Science and Technology/Rolla, MO, 65401, U.S.A ABSTRACT Corrosion processes in the steel reinforced structures can result in structural deficiency and with time create a threat to human lives. Millions of dollars are lost each year because of corrosion. According to the U. S. Federal Highway Administration (FHWA) the average annual cost of corrosion in the infrastructure sector by the end of 2002 was estimated to be $22.6 billion [1]. Timely remediation/retrofit and effective maintenance can extend the structure’s live span for much less expense. Thus the considerable effort should be done to deploy corrosion monitoring techniques to have realistic information on the location and the severity of damage. Nowadays commercially available techniques for corrosion monitoring require costly equipment and certain interpretational skills. In addition, none of them is designed for the real time quality assessment. In this study the crack sensor developed at Missouri University of Science and Technology is proposed as a distributed sensor for real time corrosion monitoring. Implementation of this technology may ease the pressure on the bridge owners restrained with the federal budget by allowing the timely remediation with the minimal financial and labor expenses. The sensor is instrumented in such a way that the location of any discontinuity developed along its length can be easily detected. When the sensor is placed in immediate vicinity to the steel reinforcement it is subjected to the same chemical process as the steel reinforcement. And corrosion pitting is expected to develop on the sensor exactly at the same location as in the rebar. Thus it is expected to be an effective tool for active corrosion zones detection within reinforced concrete (RC) members. A series of laboratory tests were conducted to validate the effectiveness of the proposed methodology. Nine sensors were manufactured and placed in the artificially created corrosive environment and observed over the time. To induce accelerated corrosion 3% and 5% NaCL solutions were used. Based on the test results, the proposed/corrosion distributed sensor is capable of delivering fairly accurate information on the location of a discontinuity along the sensor caused by corrosion pitting. Forensic study was also conducted to validate the concept. In order to test the sensors in real live condition, 27 sensors were prepared to be placed into RC beams. The beams will be subjected to corrosive environment. After that the sensors will be monitored over the time for signs of corrosion. Keywords: Corrosion sensor, coaxial cable, reinforced concrete 1. INTRODUCTION Corrosion is a naturally occurring process commonly recognized as deterioration of ferrous material when it reacts with the environment (1). Corrosion processes in the steel reinforced structures may result in structural deficiency and eventually create a life threatening situation. According to the Federal Highway Administration (FHWA) in the United States [1], there are approximately 583,000 highway bridges and among them, 235,000 are conventional reinforced concrete (RC) bridges. About 15% of them were evaluated as structurally deficient or functionally obsolete. Millions of dollars are lost each year because of corrosion, per Strategic Highway Research Program (SHRP) of the U.S. National Research Council, the average annual cost (direct) of corrosion by the completion of the 2002 was about $8.3 billion [1]. And that is the direct cost from the highway bridge infrastructure deficiency due to corrosion, whereas the indirect cost coming from the traffic delays and lost of productivity can be up to ten times greater. Timely repair and effective maintenance can extend the structure’s live span for much less expense. Thus considerable efforts should be done to deploy corrosion monitoring techniques to have realistic information on the location and the Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2011, edited by Masayoshi Tomizuka, Chung-Bang Yun, Victor Giurgiutiu, Jerome P. Lynch, Proc. of SPIE Vol. 7981, 79811L © 2011 SPIE · CCC code: 0277-786X/11/$18 · doi: 10.1117/12.879770 Proc. of SPIE Vol. 7981 79811L-1 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/08/2015 Terms of Use: http://spiedl.org/terms