Thermal Conductivity of a Gravel Layer of a Road

Abstract

Thermal resistance of the structural layers of a road is one of the important parameters that determine the choice of technical solutions of road design in the permafrost area. The purpose of this research is a quantitative assessment of the influence of the extent to which the pores in a gravel bedding are filled with ice or sand on the thermal conductivity of an ice-gravel or sand-gravel mixture. Lichtenecker formula was used to calculate the thermal conductivity coefficient of a three-component mixture. Different levels of ice content and moisture levels ofthe sand in the pores were considered. It was shown that the thermal resistance of the road structure can change significantly depending on the choice of the filler material. This allows to regulate the thermal regime of the road without adding new structural layers. The results of the calculations are presented as 2D and 3D charts to assess the influence of the filler material and the extent to which the pores are filled on the thermal conductivity coefficient of the mixture. The charts allow to see the possible changes in thermal conductivity coefficient of the structure and make a correct decision regarding the technologies to be used in construction. For example, to decide on the necessity to use a special thermal protection layer in the road structure.