2013 Session: 696

• Measurement of Subgrade Thermal Conductivity Using a Modified Triaxial Test
  Abstract: This paper describes an approach to measure the thermal conductivity of Shelby tube samples of subgrade soil using a thermal needle embedded within a modified top platen of a triaxial cell. This approach permits quantification of the thermal conductivity of the subgrade soil under the in-situ stress state, as well as during isotropic compression. Although the impact of porosity on the thermal conductivity of soil has been studied extensively, the majority of these approaches involve compaction of several soil specimens at different water contents and densities, leading to different soil structures which may affect the thermal conductivity. To show how the impact of porosity could be obtained using a single specimen, an example test was performed on a compacted silt specimen. The thermal conductivity of the soil increased with decreasing porosity during loading, and decreased during unloading, albeit on a different path.
  Authors: McCartney, John Scott; Jensen, Erik; Counts, Brennan
  Authors: McCartney, John Scott; Jensen, Erik; Counts, Brennan
  Year: 2013
  Document Type: Paper
  Subject: Geotechnology; Materials
  Session: 696
  Paper Number: 13-1866
• Temperature Effects on Soil Behavior in Relation to Ground-Sourced Bridge Deck Deicing Systems
  Abstract: The effect of temperature on soil behavior is gaining importance as energy foundations are utilized for heating and cooling of buildings as well as for deicing of bridge decks in the winter. This paper describes the effect of temperature changes on soil behavior. The results of temperature-controlled triaxial tests and oedometer tests from previous studies are evaluated to determine the general trends of soil behavior in response to temperature increase. A comprehensive review of the literature shows that an increase in temperature induces changes in the pore water pressure, volume, shear strength, and preconsolidation pressure of the soil. During an undrained triaxial test, an increase in temperature of 35⁰C can result in excess pore water pressures up to 80% of the initial consolidation pressure. The change in volume during a drained triaxial shear test not only depends on the temperature history but also on the overconsolidation ratio (OCR). Normally consolidated clays exhibit a highly contractive behavior in reponse to increased temperatures during drained loading. Lightly overconsolidated clays (OCR<2) show a smaller thermal contraction than normally consolidated clays during heating. Clays having a high OCR show highly dilative behavior during thermal loads. As overconsolidation ratio increases, clays tend to be more dilative when thermally loaded. The effect of temperature increase on shear strength is a subject of controversy. Many studies indicate that an increase in temperature strengthens the clay. On the other hand, there are also studies that indicate an increase in temperature may cause a slight reduction in clay strength. Another significant effect of temperature change is the way it influences the consolidation state of the soil. By examining the previous studies, it is found that the preconsolidation pressure decrease as the soil temperature increases.
  Authors: Sutman, Melis; Olgun, Guney
  Authors: Sutman, Melis; Olgun, Guney
  Year: 2013
  Document Type: Paper
  Subject: Geotechnology; Materials
  Session: 696
  Paper Number: 13-5022
• Thermally Induced Water Flux in Soils
  Abstract: This paper presents a comprehensive study for the formulation of the thermally induced water flux. For conditions without ice lenses, either frozen or unfrozen conditions, a theory was proposed to address the underestimation of water flux by the model of Philip and de Vries (1). In addition, experiments with a modified capillary rise method were proposed to calculate a gain factor, which accounts for this underestimation. For the thermally induced flux in frozen soils with ice lenses, a theoretical formulation was derived for the segregation potential, which is the key parameter in the model of Konrad and Morgenstern (22-24). This theoretical formulation, which is absent in previous research, is expressed in a simple mathematical form and can be conveniently used for accurate prediction of segregation potential. The validity of the theory was proven with reported data. And more auxiliary relationships were provided for accurately predicting the segregation potential with the proposed formulation.
  Authors: Liu, Zhen; Zhang, Bin; Yu, Xiong; Tao, Junliang; Sun, Ye; Gao, Quan
  Authors: Liu, Zhen; Zhang, Bin; Yu, Xiong; Tao, Junliang; Sun, Ye; Gao, Quan
  Year: 2013
  Document Type: Paper
  Subject: Geotechnology; Materials
  Session: 696
  Paper Number: 13-5149
• Effect of Temperature on Shear Strength of Recycled Asphalt Shingles
  Abstract:

  The effect of seasonal field temperature variations on shear strength of recycled asphalt shingles (RAS) improved by mixing with bottom ash (BA) was evaluated for use as structural fill material in highway embankments. Typical field temperatures ranging from 5 oC to 35 oC were induced to the compacted RAS:BA specimens. The increase in temperature reduced the shear strength of the compacted RAS:BA mixture and, therefore, temperature effects should be taken into consideration in design. The friction angle of the compacted RAS:BA mixtures, however, remains within a range suitable for stability of embankment fills. Thermal cycling induces thermal preloading to the mixtures containing RAS, which in turn increases shear strength. Based on these results, to achieve the optimum behavior, construction of highway embankments made with materials containing RAS is recommended during warm seasons. Use of RAS in high-volume structural fill applications can contribute to more sustainable roadway infrastructure.

  Authors: Soleimanbeigi, Ali; Edil, Tuncer B.; Tinjum, James M.
  Authors: Soleimanbeigi, Ali; Edil, Tuncer B.; Tinjum, James M.
  Year: 2013
  Document Type: Paper
  Subject: Geotechnology; Materials
  Session: 696
  Paper Number: 13-3109
  Practice-Ready: Yes
• Effect of Temperature on Shear Strength of Recycled Asphalt Shingles
  Authors: Soleimanbeigi, Ali
  Authors: Soleimanbeigi, Ali
  Year: 2013
  Document Type: Presentation
  Subject: Geotechnology; Materials
  Session: 696
  Paper Number: 13-3109
• Measurement of Subgrade Thermal Conductivity Using a Modified Triaxial Test
  Authors: McCartney, John
  Authors: McCartney, John
  Year: 2013
  Document Type: Presentation
  Subject: Geotechnology; Materials
  Session: 696
  Paper Number: 13-1866
• Temperature Effects on Soil Behavior in Relation to Ground-Sourced Bridge Deck Deicing Systems
  Authors: Olgun, Guney
  Authors: Olgun, Guney
  Year: 2013
  Document Type: Presentation
  Subject: Geotechnology; Materials
  Session: 696
  Paper Number: 13-5022
• Thermally Induced Water Flux in Soils
  Authors: Liu, Zhen
  Authors: Liu, Zhen
  Year: 2013
  Document Type: Presentation
  Subject: Geotechnology; Materials
  Session: 696
  Paper Number: 13-5149