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The permeability of asphaltic mixtures is controlled by the size and interconnec­tion of the void space. To illustrate this, some recent data is given in Fig. 5.1. This presents results for various hot-mix asphaltic specimens as described in Table 5.1. Figure 5.1 shows that permeability values of intact asphaltic materials are typically in the 0 […]

Andrew Dawson[7], Niki Kringos, Tom Scarpas and Primoz Pavsic Abstract Pavement surfaces provide a key route of ingress of rain water into the pavement construction. Thus, permeability of asphaltic materials and the water ingress capacity of cracks in the pavement are very important. A range of equipment exists to determine the permeability of asphaltic mixtures […]

Researchers interested in frost action in soils agree on the description illustrated in Fig. 4.3 on how ice lenses grow and cause frost heave. Nevertheless, when itcomes to the degree of water saturation of the unfrozen soil below the freezing front there are two different conceptions. Some researchers believe that the un­frozen soil is fully […]

Frost heaving of soil is caused by crystallization of ice within the larger soil voids. Ice lenses attract water to themselves by the, so-called, cryo-suction process, and grow in thickness in the direction of heat transfer until the water supply is depleted or until freezing conditions at the freezing interface no longer support further crys­tallization, […]

3.4.1 Frost Heave and Spring Thaw Frost heave occurs in roads having fine graded, so-called frost-susceptible, mate­rial, at a depth to which the freezing front reaches during the winter. A well-built road of consistent materials and cross-section can be expected to heave relatively evenly. When inconsistencies or inhomogeneities are found in the construction of the […]

The thermal diffusivity, a (m2/s), is the ratio between thermal conductivity (X) and thermal capacity (c): a = X/c (4.3) It, thus, measures the ability of a material to conduct thermal energy relative to its ability to store thermal energy. Soils of large a will respond quickly to changes in their thermal environment, while materials […]

Thermal capacity characterises the ability of a material to store or release heat. It is the important property that relates to the delay in heat transfer. The thermal capacity of water is approximately twice as high as that for most minerals and for ice, while the thermal capacity of air is negligible. Temperature (°С) Volumetric […]

Because the thermal conductivity of minerals is much higher than that of water and air, thermal conductivity of soil decreases with increasing porosity. 4.3.2 Degree of Water Saturation, Sr The thermal conductivity of air in a soil or aggregate’s pores is negligible but the conductivity increases with increasing degree of water saturation. Fine soils generally […]

For pavements, conduction of heat is the most important factor for heat transfer. During warm and sunny summer days though, the temperature of a pavement base layer under a thin asphalt concrete, may reach high values and natural convection in a fairly permeable base layer should not, then, be neglected. 4.3 Thermal Conductivity, X Mineral […]

4.2.5.1 Temperatures Below 0°C The transfer of heat by conduction is the dominating factor at temperatures below 0°C (Sundberg, 1988). In the small pores of frost susceptible soils though, due to freezing point depression, some water remains unfrozen at temperatures below 0°C. This allows convection caused by so-called cryo-suction effects (see Section 4.6.2 below) and […]