## 5 Conclusions  
Based on microwave heating and the microwave ice mechanism, a simulation model was established by the finite element method. The influence of microwave frequency and road structural material on microwave deicing efficiency was analyzed. A microwave deicing device was used to perform an indoor verification test. By comparison, the experimental results were basically consistent with the simulation results, verifying the accuracy of the simulation model. Some conclusions can be obtained:  
1. Different microwave frequencies have a great influence on microwave de-icing efficiency. Under the same conditions, the microwave deicing efficiency of 5.8 GHz is 4.31 times that of 2.45 GHz, and microwaves with a frequency of 5.8 GHz are more suitable for pavement deicing.
2. At the same microwave frequency, the microwave absorption efficiency of different road structure materials is also different. The ice-melting efficiency of cement concrete is 3.89 times (2.45 GHz) and 5.23 times (5.8 GHz) that of asphalt concrete, respectively.  
Figure 13: Comparison of deicing rates between indoor tests and simulations of different road materials.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Parameters**} & \multicolumn{4}{c}{**Cement Concrete**} & \multicolumn{4}{c}{**Asphalt Concrete**} \\ \cline{2-7}  & **1** & **2** & **3** & **1** & **2** & **3** \\ \hline Initial temperature/\({}^{\circ}\)C & \(-\)13.5 & \(-\)14.3 & \(-\)14.5 & \(-\)15.1 & \(-\)14.6 & \(-\)14.3 \\ Heating time/s & 19 & 20 & 20 & 109 & 104 & 110 \\ Temperature-rise rate/(\({}^{\circ}\)C S\({}^{-1}\)) & 0.711 & 0.715 & 0.725 & 0.139 & 0.140 & 0.130 \\ \hline \hline \end{tabular}
\end{table}
Table 9: Deicing efficiency of concrete with different pavement materials at 5.8 GHz frequency.  
At the same frequency, the effect of a temperature increase of the microwave energy absorbed by cement concrete is better than that of asphalt concrete. The effect of microwave deicing on cement concrete pavement is better. Additionally, the higher the frequency is, the more obvious the difference in the microwave energy absorbed by cement concrete and asphalt concrete is.
4. As a new type of green deicing method, microwave deicing can overcome the shortcomings of traditional deicing methods, such as mechanical deicing and the chemical method, and it has a good development trend. We should pay more attention to the application of high frequency deicing and microwave deicing in cement concrete pavement. There are many factors that affect the deicing efficiency. If the multi-layer environment, such as air, ice, concrete, etc., and the thickness of each layer can be fully considered, this paper will be more complete. Next, we will further study the output power and different ice thicknesses at the same frequency.  
[PERSON] conceived and designed the experiments; [PERSON] and [PERSON] performed the experiments; [PERSON] analyzed the data; [PERSON] contributed reagents/materials/analysis tools; [PERSON] wrote the paper.  
This research was funded by Natural Science Foundation of Shandong Province (Grant No. BS2015 SF016) and Sichuan Provincial Communications Department Science and Technology Project (Grant No. 01-2013).  
The authors declare no conflict of interest.