## 1 Introduction
Recently, scholars have applied the wave propagation of reflection signals transmitted by the ground penetrating radar to examine the corrosion phenomenon of steel bars with different thicknesses of protective layers in concrete components at different times (different status of corrosion) and have compared and analyzed the corrosion potential [12]. In recent years, the use of ground penetrating radar (GPR) at frequencies from 500 MHz to 2.5 GHz has yielded very good results for the inspection of concrete structures. The possibility of performing nondestructive measurements quickly and with convenient recording of the measurement results is particularly beneficial [13]. Two experimental cases are realized: in the first one, GPR and ERT were performed in full scale laboratory conditions where a road segment was investigated in different conditions; in the second test, a radiant floor was investigated with a comparison of the results obtained with GPR and IR. The study demonstrates the feasibility of integrating the collected data obtained with non-destructive testing to enhance the knowledge of engineering issues [14]. This study will derive and integrate the digital coded signal of ground penetrating radar electromagnetic wave scanning and electromagnetic wave transmission theory to explore the application of the reflected voltage of the corrosion product interface of steel reinforcement to the detection of corroded steel bars in concrete components and compare it with the corrosion chemical potential of corroded steel bars [15]. The use of ground penetrating radar (GPR) to find bridge corrosion was discussed. A simple pull cart was constructed with mounts for the antennas to keep the antennas an inch above the concrete surface. A threshold level was determined to differentiate between the good and the corroded rebars. The variance simulations helped to determine the reflectivity of the corroded rebar [16]. A physical model is presented for the electromagnetic signature of a buried reinforcing steel bar, which takes into account the radius of the rebar. This is achieved by subjecting GPR radar grams to a series of digital image processing stages, followed by different power reflectivity within the energy zone during the motion of the GPR antenna along the reinforced concrete surface [17]. Studies in other countries using the ground penetrating radar to detect and evaluate the corrosion of bridges found out that the corrosion products of steel bars were correlated with the electromagnetic wave signal transmitted by the ground penetrating radar. The electromagnetic wave reflection of ground penetrating radar can effectively examine the deterioration and defects of reinforced concrete. The reflected waves show the different characteristics in sound and defective reinforced concrete [18]. The comparison analysis of these two different waves can identify the defects and the degree of corrosion. Meanwhile, the comparison between the ground penetrating radar method and the corrosion potential method showed a correlation. These qualitative detections are discussed more frequently than quantitative tests. This study also explores the application of the ground penetrating radar in detecting and analyzing the interface of corroded steel bars by propagating electromagnetic waves. The contents of this research include:  
1. Electromagnetic wave propagation behavior and the principle of the reflected voltage. 2. Accelerated corrosion test of steel bars with different thicknesses of the protective layer. 3. The reflected voltage of electromagnetic waves from different corroded steel bars. 4. The detection of the electrochemical corrosion potential of different corroded steel bars. 5. Establishing a reference standard for detecting the degree of corrosion of the reflected voltage of electromagnetic waves.