• Use of Cellular Concrete for Air Convection Embankment to Protect Permafrost Foundations in Cold Regions: Feasibility Study

      Liu, Jenny; Wu, Hanli (2019-08-15)
      The air convection embankment (ACE) is a technique used to protect permafrost from thawing in road construction in cold regions. However, the desired materials needed for ACE are not readily available, which prevents its extensive use in Alaska. To overcome the limitation of traditional ACE, and further improve the cooling effect of ACE, this study investigated the feasibility of using cellular concrete as an alternative material for ACE in cold regions. The heat transfer patterns of the cellular concrete ACE, the crushed-rock ACE, and the sand/gravel embankment were studied using the numerical simulation. The results of the present study show that the cooling performance of both cellular concrete ACE and crushed-rock ACE are superior to the traditional sand/gravel embankment. The cellular concrete ACE has better heat insulation property in the summer, and the crushed-rock ACE has stronger natural convection in winter. For the annual cooling efficiency of the two different ACE techniques, the proposed cellular concrete ACE has a better cooling effect on the foundation soil than the crushed-rock ACE. These results indicate that the thermal conductivity and specific heat capacity of construction materials have significant impacts on the performance of the ACE.
    • Water Retention, Bulk Density, Particle Size, and Thermal and Hydraulic Conductivity of Arable Soils in Interior Alaska

      Sharratt, Brenton S. (School of Agriculture and Land Resources Management, Agricultural and Forestry Experiment Station, 1990-10)
      The relative proportion of liquid, gas, and solid as constituents of soil depends on factors such as climate, biological activity, and management practices. Therefore, the physical state of soil is a dynamic process, changing with time and position in the profile. Temperature, thermal and hydraulic conductivity, density, and water content are some quantitative properties characterizing the physical state of soil. These properties are important in describing soil processes such as water and heat flow, movement of chemicals, biological activity, and erosion. Water in the soil is subject to a number of forces resulting from the attraction of the soil matrix for water and presence of solutes and gravity. The energy status of water-the sum of these forces-is termed water potential. Processes such as evaporation and plant water uptake are governed by the gradient in water potential in the soil and across the root-soil interface, respectively. The term water potential is more descriptive of the soil water status than water content as movement of water is in response to differences in water potential.