Nondestructive Testing Of Steel Reinforcement Corrosion In Concrete By Electrical Resistance Tomography

The nondestructive testing of reinforced concrete is of great importance for the study of the durability of concrete structures.The detection of steel bar corrosion is the main content of concrete flaw detection.The half-cell method,the linear polarization method and the concrete resistivity method are commonly used to detect the corrosion.But this detection accuracy is not high.Therefore,it is of great significance and value to study the nondestructive testing method of steel corrosion.In this paper,the problem of corrosion detection in practical engineering is studied,and the simulation and experimental which research on the corrosion resistance of reinforced concrete are completed by resistance tomography.The specific contents are as follows:The advantages and disadvantages of different methods for detecting the corrosion of reinforced concrete are compared.This paper presents a design scheme.This scheme is to detect the corrosion of reinforced concrete by the electrical resistance tomography system.This paper studies the resistance imaging technology,including the composition structure of the resistance imaging detection system,the mathematical model and the detection method of the forward problem and the inverse problem.In this paper,the resistance imaging technique based on the finite element method is studied.Using COMSOL Multiphysics software to build a reinforced concrete open model and mixed model.Image reconstruction of the simulation model is realized by MATLAB software.CAD image models of 8 electrodes,12 electrodes and 16 electrodes were constructed by using the finite element simulation software of COMSOL Multiphysics.Image reconstruction of the simulation model is realized by MATLAB software.The influence of the number of electrodes on the imaging quality is analyzed.The Landweber algorithm,LBP algorithm,conjugate gradient algorithm,sensitivity coefficient method and Newton-Raphson algorithm are used to obtain the reconstructed image.The influence of imaging algorithm on image quality is analyzed.The color histogram program is written by MATLAB,and the image similarity obtained by different algorithms is compared and analyzed.The image similarity of different algorithms is analyzed and compared.Through the simulation study,we will use the Landweber algorithm for the detection of rebar corrosion.The experimental study on the corrosion detection of steel bars was carried out,and the data acquisition hardware system was designed and perfected.In order to get the optimal excitation signal,the sine signal generator based on STC89C52 MCU and DAC0832 chip is designed.In order to avoid the polarization of the electrode,a copper sulfate solution was used as the electrode array.The reinforced concrete experimental platform is built.Two kinds of reinforced concrete specimens with single and double steel bars are made.Accelerated corrosion tests of concrete specimens were carried out.The change of voltage signal and resistivity signal in the process of steel corrosion are recorded.The data were analyzed and the image was reconstructed.The image data of steel corrosion process are obtained,and the experimental results show that the image is consistent with the corrosion process.