Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Use of geothermal bridge deck deicing systems to mitigate concrete deterioration in Montana(Montana State University - Bozeman, College of Engineering, 2023) Turner, Ethan Joseph; Co-chairs, Graduate Committee: Kirsten Matteson and Mohammad KhosraviReinforced concrete bridge decks face deterioration from thermal stresses, frost action, and early-age cracking. This thesis presents experimental testing and numerical simulations on a bridge deck deicing system's ability to mitigate concrete deterioration. Two experimental bridge deck models were constructed with embedded heat exchanger tubing and instrumented with thermocouples and strain gauges. The models were tested in a cold chamber laboratory under conditions representative of Montana winter weather. The experimental results suggested that a bridge deck deicing system with an inlet temperature of 8 °C shows promise in deicing, reducing thermal movements, and mitigating early-age cracking through thermal shrinkage. The temperature and strain results of the experiment were used to validate a numerical model constructed in COMSOL Multiphysics. Inlet fluid temperatures of 10 °C and 50 °C, chosen from common ground temperatures in Montana, were tested to evaluate the system's effect on frost action and thermal stresses. With a 10 °C inlet fluid temperature, the system showed promise in deicing and mitigating concrete deterioration. While the system did not always raise the surface temperature above 0 °C, the consistent increase in temperature suggested that under certain weather conditions, the system could keep the top surface temperature above 0 °C for a longer period than with no system. The system was also successful in reducing the range of strain due to thermal movements. The system was not able to mitigate the effects of frost action or temperature gradients. The temperature gradients induced by the system were at times worse than without the system, but the difference was insignificant. With a 50 °C fluid temperature, the system was more effective in deicing and mitigating frost action. The range of strain from thermal movements was also reduced more than with a 10 °C inlet fluid temperature. The thermal gradients, however, were at times slightly greater than design gradients provided by design specifications. The excessive gradients, however, only occurred during extreme weather conditions that are less common in Montana. While not perfect, geothermal bridge deck deicing systems show promise for mitigating some mechanisms of concrete deterioration, while keeping other mechanisms within allowable limits.Item NMR characterization of unfrozen brine vein distribution and structure in frozen systems(Montana State University - Bozeman, College of Engineering, 2022) Lei, Peng; Chairperson, Graduate Committee: Sarah L. Codd; This is a manuscript style paper that includes co-authored chapters.The liquid vein network (LVN) that forms in the interface of ice crystals or particles exists in frozen porous media due to the freezing point depression. The distribution and structure of the LVNs are dynamic due to the ice recrystallization phenomenon. In ice alone, the LVNs formed by the ice crystal interfaces can be characterized as a porous medium in terms of surface to volume ratio (SV /) and the tortuosity (alpha).The presence of solid particles or ice-binding proteins (IBPs) make the frozen system much more complex. The research presented uses nuclear magnetic resonance (NMR) experimental techniques, including magnetic resonance imaging (MRI), relaxation and self-diffusion measurements, to study the development of the LVNs in complex frozen systems containing solid particles or IBPs. Poly-methyl methacrylate (PMMA) particles of diameters 0.4, 9.9, and 102.2 microns are used with brine solution concentrations of 15, 30, and 60 mM Magnesium chloride (MgCl 2) to simulate complex frozen systems. The dynamic rearrangement with time of LVNs can be studied as a function of temperature, MgCl 2 concentration, and PMMA particle size. The results indicate that small solid particles dominate the structure dynamics while in larger solid particle packed beds the solute effect dominates. This behavior is quantified by determination of SV / and alpha from NMR relaxation and diffusion data. Additionally, IBP produced from the V3519-10 organism isolated from the Vostok ice core in Antarctica is added to ice samples frozen from 30, 60 and 120 mM MgCl 2 solution to investigate its influence on LVNs over months of aging. The interplay of the solute and biological effects is complicated but it appears the biological effect is more pronounced at lower salt concentrations. The data provide a basis for eventual combination of salt, IBP and solid particulate studies. The result of MRI, relaxation and self-diffusion measurements indicate the inhibition of ice recrystallization as a function of particle size, MgCl 2 concentration and the presence of IBP. The non-invasive data presented along with calibration of the relaxation experiments with self-diffusion experiments, demonstrate the continued extension of NMR techniques developed from porous media to frozen porous media and ice LVN structure.Item A forest entombed in ice: a unique record of mid-Holocene climate and ecosystem change in the northern Rocky Mountains, USA(Montana State University - Bozeman, College of Letters & Science, 2022) Stahle, Daniel Kent; Chairperson, Graduate Committee: David McWethy; This is a manuscript style paper that includes co-authored chapters.Across the high alpine of the northern Rocky Mountains small vestiges of perennial ice have endured for thousands of years. These ice patches reside hundreds of meters above modern treeline, with some persisting through mid-Holocene warmth and others establishing at the onset of a cooler period that began around 5,000-5,500 years BP. Recent warming-driven melting at the margins of one ice patch high on the Beartooth Plateau of northern Wyoming exposed over 30 intact mature whitebark pine (Pinus albicaulis) tree boles, all > 25 cm in diameter. We extracted cross-sectional samples from the stems of 27 preserved logs, and radiocarbon dated annual growth rings from 11 of these trees, anchoring the chronology to a date range spanning 5,947 to 5,436 years BP + or - 51.3 years. From this fossil wood chronology, we developed estimates of warm-season, annual, and biennial average temperatures for upper-elevation treeline during the mid-Holocene. To identify the predominant climate-growth relationships of the subfossil trees, we sampled live whitebark pine trees growing at an adjacent treeline site approximately 120 m lower in elevation. Temperature was found to be the major driver of variability in tree growth at the modern treeline location, with trees producing narrower (wider) rings during periods of cooler (warmer) growing season temperatures. Using linear and non-linear transfer functions based upon the stable statistical relationship between modern tree growth and temperature, we reconstructed past temperature estimates from the ice patch subfossil ring-width chronology. Our results provide estimates of mid-Holocene warm-season (and biennial) average temperatures ranging from 5.7-6.5 °C (-0.44-0.26 °C) respectively. A multi-century regional cooling trend beginning around 5,650 years BP resulted in average temperatures declining below a warm-season (biennial) critical threshold of ~5.8 °C (-0.34 °C), likely leading to the eventual death of the whitebark pine stand and subsequent formation of the ice-patch. This high-quality paleo-ecological dataset reveals a major shift in the alpine and forest ecotone on the Beartooth Plateau following the mid-Holocene warm period and offers further insight on the thermal limits of whitebark pine trees in the Greater Yellowstone Ecosystem.Item Thermal contact resistance at the snow-ice interface: dependence on grain size(Montana State University - Bozeman, College of Engineering, 2022) Dvorsak, Michael Alan; Chairperson, Graduate Committee: Kevin HammondsSeasonal snow covers consist of many stratigraphic layers of varying density and, therefore, thermal conductivity. Weak layers can develop at the interface between these snow layers, reducing stability and increasing avalanche danger. While it is known that a bulk temperature gradient of -10?C m -1 across a snowpack enhances weak layer development via kinetic snow metamorphism, recent studies have identified an enhancement of this temperature gradient across snow interfaces. Previous work has determined that at a snow-ice interface, such as might exist around ice crusts in the snowpack, the driving factor for a temperature gradient enhancement could be a thermal contact resistance. This creates an interfacial phenomenon that induces a large temperature drop at the interface between two connected materials. The primary mechanism is a reduction of contact area for conduction to occur due to the porous nature of snow. Here, we further investigate the thermodynamics of a snow-ice interface by varying the grain size, which directly correlates to the total contact area. Within a controlled laboratory environment, a 4 mm ice lens was artificially made and placed between rounded grains that varied in size (1, 2, and 3 mm) between experiments. Temperature gradients of -10, -50, and -100 ?C m -1 were then applied across the sample. The temperature gradient was measured in-situ within 1 mm of the ice lens using micro-thermocouple measurements. The local temperature gradient at the snowice interface was found to be up to four times the imposed temperature gradient with 2-3 mm snow grains and near the bulk temperature gradient with the 1 mm grains. Following a thermal analysis, it was concluded that the enhancement in the temperature gradient was also due to a thermal contact resistance at the snow-ice interface. Utilizing timelapse x-ray computed microtomography, a microstructural characterization of the snow-ice interface was also performed, where it was observed that new ice crystal growth, kinetic snow metamorphism, and sublimation were all occurring simultaneously near the ice lens. These results indicate that the observed grain size near an ice lens or crust in a natural snowpack may be a pertinent parameter for better understanding kinetic snow metamorphism regimes that may exist at these interfaces.Item Investigation of crack arrest fracture toughness of laboratory-manufactured polycrystalline ice(Montana State University - Bozeman, College of Engineering, 2021) Alcorn, Derek West; Chairperson, Graduate Committee: Edward E. AdamsApproximately 50% of ice mass loss from ice sheets is due to icebergs breaking off in a process called calving. Icebergs are created through the incremental growth of crevasses, which are large fractures in the ice. Crevasse propagation and iceberg calving predictions within ice sheet models conflict with direct observations of crevasse processes. Current ice sheet models assume that a crevasse will propagate until it reaches a depth where the stress intensity factor at the crack tip is less than that of crack initiation, however, this is likely an oversimplification as current models over estimate crevasse depth. A more robust model would also account for the crack arrest fracture toughness, a measure of how well a material can stop an already propagating crack. Here, we calculate crack arrest fracture toughness for samples of laboratory-manufactured polycrystalline ice. These samples were created using a radial freezing technique with a reproducible grain size distribution of 0.95 mm + or - 0.28 mm analyzed by cross-polarized light. Specimens were notched and brought to failure via a short-rod fracture toughness test at controlled temperatures and a constant displacement rate in a commercial mechanical testing apparatus with an environmental chamber. The presented data agrees with short-rod fracture toughness data collected from ice cores at the Filchner- Ronne Ice Shelf in Antarctica, demonstrating quasi-stable crack growth behavior. Results show the crack arrest fracture toughness of laboratory-manufactured polycrystalline ice is approximately 25 - 50% of fracture toughness. Using the crack arrest fracture toughness determined in this study would further increase modeled crevasse depth, indicating more analysis is required. Future studies can incorporate these data to more accurately determine crevasse penetration depth and improve iceberg calving predictions within ice sheet models.Item Spectral signs of life in ice(Montana State University - Bozeman, College of Engineering, 2020) Messmer, Mitch Wade; Chairperson, Graduate Committee: Christine ForemanIn astrobiology, new technologies are being implemented in the search for extraterrestrial life. Interpreting results from new analytical techniques requires additional information about microbial properties. A catalogue of identifying characteristics, called biosignatures was created for bacterial and algal isolates from Greenland and Antarctica by measuring substrate utilization, UV/Vis absorbance, Fourier-Transform Infrared Spectroscopy, and Raman spectroscopy. Organisms were chosen from environments analogous to Martian glacier systems. Spectral properties of these polar isolates could serve as a reference for interpreting results from NASA's Perseverance rover. Substrate utilization was evaluated using EcoPlates on an Omnilog plate reader (Biolog, California, U.S.A.). UV/Vis absorbance spectra indicated that nine of the twenty-five bacterial isolates contained carotenoid pigments, and one contained violacein. UV/Vis analysis was effective at identifying the presence of pigments, but was insufficient for distinguishing between the types of carotenoids. FTIR analysis identified general biological features such as lipids, proteins, and carbohydrates, but did not detect pigments. Raman analysis of isolates with a 532 nm laser identified both the presence of carotenoid and violacein pigments, and the general cell features observed with FTIR. The degree of saturation of membrane lipids was evaluated for the bacterial isolates by comparing the ratio of unsaturated and saturated fatty acid peaks in the Raman spectra. Results were similar for the polar isolates and mesophiles, excluding the Bacillus subtilis spores. A principal component analysis was conducted to determine the regions of the spectra that contributed the variability between samples. The spectra of the bacterial isolates were more closely related based on colony color than phylogeny. Analysis of the algal isolates indicated that chlorophyll A and B fluoresced under exposure to the 532 nm laser, creating definitive biosignatures for algae. These analytical techniques proved effective at identifying cell properties that could serve as biosignatures for identifying microbial life. Identification of the spectral features of these cellular components may aid in narrowing the search for extraterrestrial life by highlighting specific target regions within the Raman spectra. Characteristics of these polar microbes may provide the foundation for interpreting spectral data collected from future explorations of extraterrestrial environments in the search for astrobiology.Item Landslide morphology and its insight into the timing and causes of slope failure: case study of post-glacial landslides in Yellowstone National Park(Montana State University - Bozeman, College of Letters & Science, 2018) Nicholas, Grace Ellen; Chairperson, Graduate Committee: Jean DixonLandslides are ubiquitous to post-glacial landscapes worldwide. Withdrawal of glacier ice exposes over-steepened landscapes that may be unstable, and consequently susceptible to landsliding. Glacial debuttressing may directly destabilize slopes; however, seismicity and transitions to interglacial climates associated with greater effective moisture and subsequent degradation of permafrost may also play a role. Here, we explore disparate potential mechanisms of slope failure in a set of post-glacial landslides in northwest Yellowstone National Park. We quantify spatial relationships, topographic metrics, and relative age of eight landslides within the north entrance to the park, a system traversed by over 700,000 visitors every year. Analysis of high-resolution topography indicates increasing surface roughness of non-active landslides southward. These roughness values in ancient slides are roughly half those of the active Slide Lake Landslide, and suggest younging ages along the retreat path of the Yellowstone Ice Cap, consistent with glacial debutressing as the likely trigger for these slides. However, roughness values and their application for relative age dating are strongly confounded by topographic biases such as gullying, fluvial erosional contacts, and anthropogenic features (e.g., roads, structures). Once roughness biases are removed, we find roughness differences between landslides decrease, and do not support younging ages along the path of ice retreat. Thus, glacial debuttressing most likely only had a preparatory influence on slope failure, and was not the direct trigger. Analysis of subsurface soils at landslide toes indicate a >17 plasticity index, pointing to highly expansive clays that are sensitive to moisture addition. Stratigraphic relationships between post-glacial terraces and soil analyses suggest a late Pleistocene (~13 - 11.5 ka) timing for slide initiation, a period coincident with high available moisture. Stream power analysis indicates that Holocene incision of the Gardiner River is focused at a knickpoint locally coincident with the toe of the active Slide Lake Landslide, providing a mechanism for modern, local reactivation of the ancient slides. Together, our findings broadly show how quantifying the temporal and spatial patterns of landslides can be diagnostic of the controls on slope failure, and can be used to understand risk. They also highlight the importance of careful site calibrations and bias removals in roughness analysis.Item High-resolution thermal expansion and dielectric relaxation measurements on H 2O and D 2O ice Ih(Montana State University - Bozeman, College of Letters & Science, 2017) Buckingham, David Tracy Willis; Chairperson, Graduate Committee: John J. NeumeierIce Ih, formed by freezing liquid water below 273 K at atmospheric pressure, is well known and highly-studied, but some of its fundamental physical properties have mystified scientists since the early twentieth century. The thermal expansion is one of those properties; the low relative-resolution of past measurements has left questions regarding the structural isotropy and negative thermal expansion (NTE). Furthermore, the existence of relaxation phenomena near 100 K, related to the residual entropy at 0 K, may reveal itself through subtle features in the thermal expansion and, thus, warrants further investigation. Here we measure the thermal expansion of ultra-pure single crystal ice from 5-265 K with 10 6 times higher relative resolution than has previously been made. The data reveal a distinct crossover to NTE below 62 K, and a third-order transition along the crystallographic c-axis near 100 K, as evident by an unambiguous relaxational decrease in the thermal expansion coefficient on cooling. To further understand the nature of the transition, isotopic substitution and dielectric measurements were performed. Three properties of the dielectric relaxation in ice were probed at temperatures between 80-250 K; the thermally stimulated depolarization (TSD) current, static electrical conductivity, and dielectric relaxation time. The dielectric data agree with relaxation-based models and provide for the determination of activation energies which identify the dielectric relaxation in ice as being dominated by Bjerrum defects below 140 K. An anisotropy was also found in the data which revealed that molecular reorientations, in the form of propagating Bjerrum point defects, are energetically favored along the c-axis between 80-140 K. Furthermore, a similar relaxational effect to that observed in the thermal expansion was observed in the TSD current along c, which provides a strong correlation between dielectric relaxation and inherent thermodynamic relaxation in ice. Finally, isotopic substitution in both measurement sets indicates the transition is related the movements of hydrogen nuclei, not those of the whole molecule, and provides details about the low temperature phonon modes. These findings paint a picture of ice as a proton-disordered crystal which undergoes a partial ordering on cooling near 100 K but, before an ordered equilibrium state is realized, the exponentially increasing relaxation time rapidly slows the ordering and ultimately freezes-in the residual entropy, causing a continuous decrease in the thermal expansion coefficient.Item The development and validation of a snow/icepack pavement temperature thermodynamic model(Montana State University - Bozeman, College of Engineering, 2002) Bristow, Jeffrey RyanItem A spectrually integrated temporal albedo model for thin composite layers of snow and ice on roads(Montana State University - Bozeman, College of Engineering, 2001) Beddoe, Andrew Gregory