# Study on Microwave Deicing of Carbon-Fiber-Modified Concrete under Multi-Factor Coupling Effect
## 5 Discussion  
The reflection and absorption of microwave are selective. When encountering metal objects, a large number of reflections are generated, whereas when encountering insulating objects, most reflections are transmitted and continue to spread in the insulating body, resulting in loss of heat [15]. Therefore, when the microwave irradiates on concrete pavement with accumulated ice, it can directly irradiate the concrete through the ice, causing the concrete to heat up and melt the ice, weakening the binding force between the ice and concrete and achieving the effect of deicing. After microwave irradiation on the surface of the concrete specimen, the free electrons in the conductor inside the concrete move, and a charge appears on the surface of the conductor, resulting in an electric field equal  
Figure 13: Simulation results of different ice layers and heights. (**a**) 20 mm, no ice; (**b**) 40 mm, no ice; (**c**) 60 mm, no ice; (**d**) 20 mm, no ice; (**e**) 40 mm, no ice; (**f**) 60 mm, no ice. to and opposite to the applied electric field, which is called electrostatic balance. When the microwave acts on the surface of the conductor, due to the high frequency conversion of the applied electric field, the surface of the conductor forms an oscillating current and continues to radiate outwardly. The macroscopic manifestation is reflected microwaves. An ideal conductor can reflect all the microwaves without transmitting wave insides [27]. When the applied electric field acts on the dielectric field, because the electrons are in a bound state, there are almost no free electrons, and only microscopic relative displacement can occur, resulting in a dipole field. The directional arrangement of the dipole produces an electric field inside the dielectric field in the opposite direction to the applied electric field, and the electric field is smaller than the external electric field, which is called dielectric polarization. Under the action of an external electric field, a dipole field is generated by relative displacement of positive and negative charge centers, which is also called displacement polarization (as show in Figure 14). Because positive and negative charge centers do not overlap, the polar molecule itself is a dipole. Under the action of an electric field, not only is the dipole vector further shifted and polarized, but the thermal motion state of the molecule is also aligned with the chaos from the opposite direction, which is called turning-direction polarization, also known as orientation polarization. When the frequency the microwave changes to 2.45 GHz, a dipole polarization lag occurs with a high-frequency electromagnetic field. This process requires a thermal motion and interactions between molecules, producing a large amount of friction, which causes the external electromagnetic field energy to oscillate. The energy is converted into internal energy, and the macroscopic properties of microwave energy can be converted into thermal energy, called polarization loss, which is the main microscopic factor of microwave heating [28]. After the polarization of the medium, polarization loss occurs, so that the power of the electromagnetic field gradually attenuates, and the electric field gradually decreases along the depth of the medium, converting microwave energy into heat energy. The electric field calculation Formula (1) is as follows:  
\[E(x)=E_{\text{max}}e^{i\omega t-\gamma x} \tag{1}\]  
where \(E_{\text{max}}\) is the maximum electric field intensity of microwave refraction into concrete, which depends on the incident electric field intensity and reflectivity; and \(\gamma\) is the propagation coefficient, which depends on the complex permittivity and complex permeability. Figure 14: Simulation diagram of charge change in the conductor.