| Abstrakt: |
Asphalt-concrete and cement-concrete mixes are road and construction materials that are vulnerable to the adverse influence of temperature on their thermal strength since they operate in open environments and are exposed to frequent seasonal and daily temperature variations. This is because asphalt concrete and cement concrete contain micropores and microcapillaries partially or completely filled with water. Based on the thermoelasticity theory, it is shown that the additional thermostresses are concentrated in a narrow zone of the binder and are the principal cause of its destruction. In this research, significant emphasis is placed on the theoretical examination of the thermal stress state of the composite matrix surrounding a pore and a capillary. This analysis considers the influence of the compatibility or incompatibility of the thermomechanical properties, such as modulus of elasticity, Poisson's ratio, volumetric coefficient of thermal expansion, brittleness, or plasticity of the solid phases in two-phase matrix–water and matrix–ice systems. These considerations apply at various stages, including pre-freezing, freezing, and during critical temperature drop. In this study, we take into account the special thermomechanical properties of water during its phase transition from a liquid to a solid state, which are associated with its incompressibility, the change in the sign of its volumetric coefficient of thermal expansion at a temperature of 4 °C (3.98 °C) and an increase in the volume upon freezing. Based on the solutions of thermoelasticity equations, it is shown that the additional thermal stresses are concentrated in a narrow neighborhood of the contact surface and are the main cause of local destruction of the system. [ABSTRACT FROM AUTHOR] |
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