The Study Of Steel Corrosion Detection Technology Based On Galvanostatic Pulse Method

Reinforced concrete is widely used in construction industry for buildings, bridges and so on. With the increasing of ages in services, the failure destruction brought by reinforcement corrosion becomes the primary cause and mode of structure failure. Therefore, the research on the detecting techniques and evaluation methods with high reliability is of engineering significance. On the on hand, the destruction issue caused by reinforcement corrosion becomes increasingly important. On the other hand, domestic detection industry of reinforcement corrosion is faced with the contradiction among backward criterion, slow-motion method and single-function equipment. Based on the comparison and analysis of current detection methods and equipment, this paper adopts electrochemical detection method of galvanostatic pulse to carry on a research and development. Thus it will provide reference for building a detection equipment system of reinforcement corrosion with independent intellectual property rights.Combined with existing detecting techniques, this article sets up a suit of detecting system which applies to on-site detection. Based on the principle of point module development, the system realizes Pulse constant-current source function with the 51 single chip microcomputer. It accomplishes Response to a potential acquisition. Signal processing, parameter determination in test process, corrosion result display and so on using embedded controller. It implements uniform distribution of electricity on the surface of reinforcement using three-electrode system on account of guard-ring electrode. It involves both independent development and integrated innovation. At last, we can carry out on-site test experiment on testing system and compare the test result with foreign equipment of the same type. The main conclusions are as follows:1. Numerical control pulse constant-current source module can setup current value function by both serial port and keyboard. It displays current value on LCD screen and transmits current value by Serial port in real-time. It outputs electricity in size of 5-200 uA while error percentage less than 5% and the pulse time is 10 seconds.2. Reinforced concrete system is based on galvanostatic pulse method and reinforcement corrosion potential signal of Randle circuit model is low frequency signal. The signal mainly distribute below 25 Hz. A/D convertor with 8 channel and 12 place integrated by S3C6410 chip can meet the requirement that sample frequency is lower than 50 Hz. Potential signal whose precision is 1 mV is without distortion collection.3. Reinforcement corrosion testing software based on Windows CE system will finish parameter determination in testing process, testing process and result display, signal acquisition and processing, communication and so on. It is stable and reliable in operation. With great man-machine interaction and easy operation, it is able to meet on-site testing requirement.4.The corrosion detection system can effectively collect and analyze data to geta more reliable detection results.As to steel bar in concrete under a state of activity,corrosion potential and corrosion current density error less than 20% compared with similar foreign equipment.As to steel bar in a passive state,corrosion potential parameters is less than 10%, corrosion current density parameters is smaller so that test error is bigger,but the overall error is lower than 42?A/ cm..