Journal of Cold Regions Engineering

During winter, large amounts of salt are used on roads to keep them safe for vehicular traffic. However, applying high levels of salt is harmful to the environment, vehicles, and infrastructure. In order to optimize the amount of salt used on roads without compromising traffic safety, it is useful to increase our knowledge about how salt affects snow properties. This study investigates the effects of salt solution on snow when a tire rolls over it. An indoor test experiment was developed to study the compression, compaction, and squeeze-out mechanisms of salted snow. Dendritic artificial snow was mixed with different amounts of salt solution from 0 to 40% by weight. The main findings of this study are that snow containing a salt solution compresses to a higher density; more snow gets squeezed out of the contact area compared to fresh snow. The snow that becomes compacted under the weight of tires is weaker when a salt solution is present. These effects take place using relatively small amounts of salt solution (10% by weight). These results can be used to optimize salt applications rates during a snowfall, an assertion that is discussed in this paper.

Storage of snow has become of increasing interest for the winter business industry. Covering a pile of snow with an insulating material protects the snow from heat transfer from the surroundings and reduces the melting. Storing snow enables ski resorts to set an opening date, and it can also be used to secure winter sports events that are dependent on snow. Cover materials that are commonly used as insulation are wood-based materials, such as sawdust, and textile materials and sheets. How efficiently a cover material functions as thermal insulation depends on the material characteristics and thickness of the insulating layer. In this study, results from a laboratory experiment are presented, which aimed at comparing different commonly used cover materials, as well as some other materials that have not previously been used as thermal insulation on snow. Different layer thicknesses were also investigated. The results show that the insulating capacity of sawdust is reduced with time. Despite degrading insulating properties with time, sawdust is still considered one of the best materials to use as insulation on snow, and it is also more efficient than the textile materials investigated in this study. Doubling the textile layers or adding a three-dimensional (3D) spacer textile, which implies adding a layer of air between the textile and the snow, reduces the snow melting. Water absorption, water transport, and evaporation of water affect the melting. In this work, evaporative cooling did not prove to reduce melting; therefore, it was not evident whether a textile material should be permeable. An interesting material used in the study was Quartzene, which absorbed all the melt water and protected the snow most efficiently of the materials tested.

Surface deflection is a flexible pavement mechanical response caused by vehicle loading and is a value representative of the overall bearing capacity of the layered system. Due to the stiffness variation of asphalt concrete material when temperature changes, as well as the stiffening of soils and unbound granular materials when temperatures drop below 0°C, surface deflection greatly varies throughout the year in areas subjected to seasonal freezing. A laboratory study was undertaken to document the relationship between frost penetration, surface deflection and axle loads. This study was performed using a heavy-vehicle simulator and an indoor test pit. A model that relates relative damage, with respect to damage induced at a reference temperature and standard axle load, to frost depth is proposed. An equivalence factor between variation of frost depth and variation of axle load is proposed as part of the model development. The proposed model, developed for one flexible pavement structure, is implemented for different reliability levels so it can be extended to other structures with engineering judgement. The combined consideration of load and frost penetration on pavement damage make the model an appropriate tool for winter weight premium analysis.

Temperature is an important factor when considering the mechanical properties of engineering materials because they can change drastically as temperatures change. The research presented here is an experimental investigation to determine the changes in the compressive behavior of concrete that occur because of low exposure temperatures. The primary purpose of the research is the development of detailed experimental stress–strain relationships exposed to low temperatures, which remains a largely unexplored topic. A total of twenty-seven $101.6\times 203.2\mathrm{mm}$ concrete cylinders were tested in uniaxial compression at the University of New Brunswick. The specimens were exposed to temperature ranges from 20°C to $-70°\mathrm{C}$ to simulate extreme climatic temperatures and those obtainable in industrial storage facilities. The compression strain of specimens was obtained by using three-dimensional digital image correlation. The mechanical properties studied were the relative changes in compressive strength, modulus of elasticity, and peak strain attributable to temperature variations. Predictive equations and relationships for these properties with respect to temperature are presented and compared with the existing literature.

The migration of groundwater often results in subgrade damage such as fracturing, pavement pumping, and cracking in seasonally frozen soil areas. Indoor tests were performed to simulate moisture migration in different soil types usually found in seasonally frozen soil areas. The results indicate that the moisture migration rate of the wetting front in clay is the fastest, followed by that in fine sand and silt. In addition, the migration height of fine sand is much lower than that of both clay and silt, whereas the water flux is larger than that of clay and silt. Moreover, under a freeze-thaw cycle, the trends of water content change and temperature distribution of the three samples at the initial state and final state were similar. Based on the gravity, matric, and temperature potentials, the moisture migrated continuously throughout the freezing process, and the temperature gradient could cause moisture to migrate faster than usual. According to the mechanism of moisture migration in the indoor tests, a case study and field test of the Jixi–Nehe Highway were undertaken in Heilongjiang Province, China. The field test results show that the moisture migration in the seasonally frozen region is consistent with the results of the indoor tests. Highway construction could significantly increase the water content of soil at the original position in the subgrade. Some measures were put forward to protect the subgrade from damage caused by moisture migration.