Journal of Cold Regions Engineering

Changes in air and ground temperatures can lead to degradation of permafrost, thawing of ground ice, and damage to linear infrastructure such as highways, railways, airfield runways, and pipelines. As part of research into the behavior of road embankments on degrading permafrost, ground temperatures under an instrumented highway embankment were recorded over 4 years. The project site is located 18 km north of Thompson, Manitoba, Canada. Thermistor strings were among several types of instruments installed beneath the toe, midslope, shoulder, and centerline of the embankment. The principal objective of the research was thermal numerical modeling of current and projected future ground temperatures in the embankment and its foundation. Measured ground temperatures were used with local climate records to calibrate a two-dimensional thermal numerical model. Future changes projected by climatologists were then used to simulate potential long-term temperature in the embankment.

Asphalt pavement properties (strength, durability, bearing capacity, etc.) are considerably affected by environmental conditions. Because of this fact, regions with severe climates (high thermal gradients, abundant precipitation, presence of freeze-thaw cycles, solar radiation, etc.) have serious problems in maintaining the functional integrity of these infrastructures. Thus, it is necessary to develop new materials that could extend the service life of these pavements without increasing the construction costs. Accordingly, the present paper studies the improvement of the mechanical performance of high-modulus asphalt mixtures through the addition of acrylic fibers, for their use under severe environmental conditions. For this purpose, different tests were carried out [thermal stress restrained specimen test, immersed wheel-tracking test, freeze-thaw sensitivity test, and UGR-FACT (University of Granada-Fatigue Asphalt Cracking Test)] under variable conditions (simulating cold and hot scenarios). The results show that the use of acrylic fibers improves the mechanical behavior of high-modulus asphalt mixtures (at high and low temperatures, as well as under the presence of water and ice), and could thus be considered an interesting alternative for extending the service life of asphalt pavements in severe climates.

This paper presents the results of a study carried out to monitor the structural behavior of a flexible pavement in cold regions, which is significantly affected by environmental factors and traffic loads. In this study, a heavy vehicle simulator was used to simulate traffic load and to provide enough cooling energy to create a freezing environment. The mechanical response of the typical Quebec flexible pavement structure during freezing was investigated using this research tool. An empirical model was also proposed and validated to describe the effect of each pavement layer on the mechanical behavior variation during freezing. The results show that the changes of moisture content and matric suction for unbound materials have a good correlation with the frost state of surrounding materials. The mechanical responses, including strains and stress, experience a regular variation along with the increase of frost penetration. The model indicates that the asphalt layer is playing a significant role in all the mechanical response variations. As for the role of other layers, the mechanical response variation for a given layer is mostly dependent on its condition and its neighboring layers.

The Calvert Cliffs form much of the western coastline of the Chesapeake Bay in Calvert County, Maryland, and are actively eroding, resulting in a critical situation for many homes in close proximity to the slope’s crest. Past studies have qualitatively shown that where waves do not regularly interact with the slope toe, the main control mechanism for slope recession is freeze-thaw events. In this study, an attempt was made to quantitatively assess the validity of this claim by analyzing the recession rate and freeze-thaw behavior of six study sites along the Calvert Cliffs that are not directly affected by waves. The freeze-thaw susceptibility of soil can be quantified by assessing its material and thermal properties. The freezing can also commonly be quantified using a freezing index. For a temperate climate like that of the Calvert Cliffs, however, a freezing index is not an effective way to quantify freeze-thaw behavior due to a lack of a well-defined freezing season. Instead, the study investigated the following two parameters: (1) days of freezing, and (2) number of freeze-thaw cycles, in addition to freeze-thaw susceptibility, to quantify freeze thaw. Results indicate that using days of freezing and/or freeze-thaw cycles may be more appropriate metrics for quantifying the effects of freeze-thaw in temperate climates like that of the Calvert Cliffs.

Snow compacting on roads may become hazardous for traffic. Chemicals such as sodium chloride are therefore often used to prevent crust formation. Melting has been believed to be the mechanism through which a chemical does this. A recent study, however, indicates that reduced contact-bonding between ice crystals may be important. This hypothesis was tested by designing an experimental set-up capable of measuring the contact-bond strength between ice and a substrate. In this paper, ice–ice contact bonding was measured in air and in a sodium chloride solution. The study showed a statistically significant decrease in the median bonding force, from 0.57 N in air to 0.33 N in solution. The weakened contact-bonding in presence of a solution might explain the soft and noncompacting snow often seen on roads, an insight which might allow a more-efficient use of chemicals during snowfall.