Numerical Investigation of the Temperature Field Effect on the Mechanical Responses of Conventional and Cool Pavements

Abstract

Conventional asphalt pavement has a deep surface color and large thermal inertia, which leads to the continuous absorption of solar thermal radiation and the sharp rise of surface temperature. This can easily lead to the permanent deformation of pavement, as well as aggravate the urban heat island (UHI) effect. Cool pavement with a reflective coating plays an important role in reducing pavement temperature and alleviating the UHI effect. It is of great significance to study the influence of temperature on the mechanical response of different types of pavement under vehicle loading. Therefore, this study examined the heat exchange theory between pavement and the external environment and utilized the representative climate data of a 24 h period in the summer. Two kinds of three-dimensional finite element models were established for the analysis of temperature distribution and the mechanical responses of conventional pavement and cool pavement. The results show that in this environmental condition, conventional pavement temperatures can exceed 50 °C under high temperatures in summer, which allows for the permanent deformation of pavement and further affects the service life of asphalt pavement. The temperature difference in a conventional pavement surface between 6 h (24.7 °C) and 22 h (30.2 °C) is much less than that between 22 h (30.2 °C) and 13 h (50.1 °C) in the summer. However, the difference in the vertical displacements of the pavement surface between 6 h and 22 h is much larger than that between 22 h and 13 h. One reason is that the difference in temperature distribution between the morning and night leads to changes in pavement structure stiffness, resulting in significant differences in vertical displacement. Cool pavement has a significant cooling effect, which can reduce the surface temperature of a road by more than 15 °C and reduce the vertical displacement of the pavement by approximately 11.3%, which improves the rutting resistance of the pavement. However, the use of cool pavement will not change the horizontal strain at the bottom of the asphalt base and will not improve the fatigue resistance of asphalt pavement. This research will lay the foundation for further clarifying the difference in the mechanical properties between the two types of pavements in the management and maintenance stage.

Heat Transfer Analysis of Warm Guss Asphalt Concrete for Mini-Trench Overlaying

“…In this section, the theory of heat transfer, finite element analysis, model construction, physical properties, initial conditions, boundary conditions, and analysis methods are respectively described. ABAQUS, a finite element analysis program, was used to analyze the effect of the heat of the guss asphalt mixture on the temperature change of the pavement and buried pipe [ 2 , 25 , 26 ].…”

“…Based on the first law of thermodynamics that thermal energy is conserved, the conservation of thermal energy in the numerical domain can be expressed as follows [ 25 , 26 , 27 ]. where, is the density (kg/m 3 ), C is specific heat (J/kgK), T is the temperature at each location over time, t is the time, is a vector operator, and is the heat flux vector.…”

“…In Equation (1) above, can be interpreted as ∇ ⋯ and ∇ is the divergence operator. According to Fourier’s law of heat conduction [ 25 , 26 , 27 ], the heat flux vector can be expressed in relation to the temperature gradient, as shown in Equation (2) below. where, is the thermal conductivity matrix.…”

“…The boundary conditions for heat transfer analysis are generally considered to be of three types. The heat that directly enters the model surface, such as solar radiation, convection from the model surface, and radiant heat emitted from the model surface to the outside [ 25 , 26 , 27 ]. The heat flow directly to the surface can be expressed as Equation (5) below.…”

“…The heat flow acting on the surface by convection is given by Equation (6) below. where is the convection coefficient, is the surface temperature, is the air temperature [ 25 ]. The radiant energy exchange between the surface of the model and its surroundings is where long-wave radiant intensity balance, is the effective emissivity, is the Stefan Boltzmann constant.…”