Economic Efficiency of Using Thermal Insulation Mixtures in Road Construction in the Cryolithozone

The subject of this research is automobile roads in permafrost zones, which are subject to the negative effects of cryogenesis. The focus of the study is on thermal insulation coatings based on mixtures of insulating and heat-accumulating construction materials. The work aimed to determine the area of economic efficiency of using mixtures of construction thermal insulation materials in road pavement structures for the cryolithozone. One possible option for reducing the construction costs of roads in the cryolithozone is the use of thermal insulation layers in road pavements made from thermal protection mixtures, which consist of a heat-accumulating binder (such as sand or gravel) and a heat-insulating filler (expanded clay, azurite, polystyrene granules, or glass debris). The influence of the thermal-physical characteristics of the binder and filler on the economic viability of using thermal insulation mixtures in road pavements has been investigated. To facilitate the analysis, two new dimensionless simplexes have been introduced. The thermal-physical simplex characterizes the ratio of the thermal conductivity coefficients of the filler and binder. The economic simplex characterizes the ratio of the cost per unit volume of the filler to the cost per unit volume of the binder. A target function has been constructed, allowing for the calculation of the conditions under which the ratio of the cost of filler to the cost of binder makes the use of material mixtures (compared to a homogeneous equivalent layer of binder with respect to thermal resistance) economically efficient. Basic quantitative patterns have been obtained, characterizing the relationship between the concentration of the filler and the dimensionless simplexes: thermal-physical and economic. A dependency has been derived for determining the limiting value of the dimensionless cost simplex, enabling the identification of the boundary of economic efficiency when using thermal insulation mixtures with varied thermal and physical properties. It has been shown that thermal insulation material mixtures can be recommended as an economically efficient alternative to homogeneous construction materials when designing road pavements. A 3D graph has been constructed to quickly assess the conditions under which the specific cost simplex value makes it advisable to apply a particular thermal insulation binary mixture in road pavements.