Mathematical modeling of thermal stress development in a bituminous matrix with modified rubber crumb

Purpose. The purpose of this study is to theoretically model the thermo-stress state of asphalt concrete containing rubber inclusions coated with a modified interfacial layer. Methodology. Based on the methods of thermoelasticity theory and using a three-dimensional spherical model of a rubber inclusion embedded in an asphalt concrete matrix, the thermo-stress state of an asphalt concrete pavement containing modified rubber crumb with different thicknesses of the modified surface layer, as well as without such a layer, was analyzed. Findings. The study established that an increase in the depth of modification penetration into the rubber crumb, i.e., the thickness of the interfacial layer, reduces the level of thermal stress concentration in the bitumen and decreases the corresponding stress gradients. It was demonstrated that special chemical treatment of rubber inclusions eliminates the drawbacks associated with their use in bitumen–rubber mixtures under variations in ambient temperature. The results of the study indicate that the thermal stresses in the components of the pavement composite are proportional to the difference between the coefficients of linear thermal expansion of its constituents. Originality. It has been theoretically substantiated that the formation of a modified interfacial layer with intermediate thermomechanical properties between rubber and bitumen makes it possible to compensate for the specific adverse properties of rubber crumb, namely, its high shear deformability and incompressibility under hydrostatic compression. These properties contribute to raveling and accelerated aging of the pavement. Practical value. The practical significance of the obtained results lies in the fact that the theoretical modeling results make it possible to determine the levels of thermal stress concentration and provide a sound basis for selecting the parameters of chemical modification of rubber crumb to prevent raveling of asphalt concrete pavement.