**6. Conclusions**

Based on the research and analysis carried out, the following was concluded:

	- (a) up to 11% when measuring in negative ambient temperature
	- (b) up to 11% during measurements of the asphalt's slab surface covered with water film
	- (c) up to 8% during measurements of the ice-covered asphalt's slab surface
	- (d) up to 16% when measuring asphalt slab with a surface covered with a thin layer of fresh snow
	- (e) even 29% during measurements of asphalt slab with a surface covered with a layer of de-icing salt

After applying correction factors for dielectric constants, the error in determining the thickness was reduced (especially the error in measuring the thickness of the surface covered with de-icing salt). The average thickness determination errors were reduced:


It should be noted that the correction coefficients have been calculated as the average of the coefficients for 5 slabs with different HMA wearing courses for specific atmospheric conditions. To significantly reduce the error, a dielectric constant correction factor calculated for a specific HMA wearing course should be applied.


**Author Contributions:** Conceptualization, M.W., A.L. and A.G.; methodology, M.W., A.L.; software, M.W.; validation, M.W.; formal analysis, A.L. and A.G.; investigation, M.W.; resources, M.W., A.L. and A.G.; data curation, M.W.; writing—original draft preparation, M.W.; writing—review and editing, A.L. and A.G.; visualization, M.W.; supervision, A.L. and A.G.; project administration, M.W., A.L. and A.G.; funding acquisition, M.W., A.L., and A.G. All authors have read and agreed to the published version of the manuscript.

**Funding:** This paper was co-financed under the research gran<sup>t</sup> of the Warsaw University of Technology no. 504/04512/1080/43.070046 supporting the scientific activity in the discipline of Civil Engineering and Transport.

**Acknowledgments:** The paper was prepared in the framework of the agreemen<sup>t</sup> between the TPA Sp. z o. o. research laboratory and a Faculty of Civil Engineering, Warsaw University of Technology on a cooperation in the field of research, education and human resources.

**Conflicts of Interest:** The authors declare no conflict of interest.
