Study On Reliability And Engineering Application Of Wireless Sensors For Monitoring Corrosion Of Steel In Concrete

The corrosion of steel reinforcement in reinforced concrete structures constitutes an alarming problem. It results in a reduced service life for the structure and the need for expensive repairs. Therefore, early detection of corrosion risk is crucial from structural and financial perspectives. However, the corrosion initiation process is quite slow, and it is difficult for engineers to detect the presence of corrosion until after structural damage has occurred. To combat this problem, researchers at the Nanjing University of Aeronautics and Astronautics developed a kind of low-cost, passive, wireless sensors that are used for detecting the onset of corrosion of the embedded reinforcement. At present, the basic circuit designs and manufacture for the sensor are finished. However, the research regarding the durability, reliability and engineering application is relatively few.The reliability of wireless sensors for monitoring corrosion of steel in concrete are investigated through theory and experiments in this paper. At the same time, the sensors have been applied to the practical engineering, and the application guideline is compiled according to the research results in the end.The main contents and conclusions are as follows:1. Based on the reliability theory analysis of sensors and the reliability principle of intensifying test, four experiments have been designed and implemented in this paper, including resistance to salt solution erosion test, impact test, high temperature hot and humid test and low temperature test. And the reliability and durability of sensors are confirmed through the experiments, the reliability of sensors under various stress are all up to 95%.2. In this paper, three reinforced concrete beams embedded wireless sensors are designed and constructed, and two testing programs are developed. In the first series of tests, the lading test of the three beams is carried out, and when the load reaches 40% of the ultimate bearing capacity, stop the test. The results show that the wireless sensors have a good reliability with sustained lading. In the second series of tests, the embedded wireless sensors and steel are subjected to accelerated corrosion by alternating wet/dry cycles. And the results indicate that the sensors work well and have a good durability and stability during the past trials.3. The twenty-eight wireless sensors are applied to the practical engineering, and the installation and protection measures to improve the survival rate of sensors are summarized in this paper. During the monitoring of more than one year, the wireless sensors show a highly working capability, and the stability and reliability of the sensor are also verified further.4. According to the previous study results and research results in this paper, the application guideline of wireless sensor for monitoring corrosion of steel in concrete has been compiled finally.