Emissivity Measurements of Road Materials

In the future, roads will have to tell the drivers what they are, whatever the conditions are. The accent is specially put on on-board infrared vision so as to understand how weather phenomena can change the surface of the road (presence of ice, …). The determination of the emissivity is necessary to reach the road surface temperature. Some research has been undertaken on several conventional materials. Their emissivities were determined by the indirect method considering the conditions to apply Kirchhoff's law were met. An infrared hemispheric and isotropic source was used to create a periodic modulated heat flux to which the considered roads materials were submitted to. Measurements presented in this study have shown differences according to road structure (average particle diameter size) and composition. Emissivity measurements conducted on different salt types used for winter maintenance have shown they can be sorted according to their origin.