Highway subsoils in cold countries are subject to increased thermal conductivity, disruption of natural moisture circulation as well as dynamic loading and application of de-icing chemicals in the winter months. In this work, the moisture mass transfer in a state of vapour flow and the de-icing chemical migration were considered during unidirectional freezing. The moisture mass transfer in a gaseous state was previously widely neglected in the exploration of frost heave. To conduct freeze-thaw cycles with increased lengths of soil samples and a modified slow freezing technique, an environmental chamber of nine samples capacity was designed. Supplying the non-saline samples with either 11 or 22 g/L sodium chloride solution signified chemical mass transport over the sample length and a significant change in temperature-moisture distribution when compared to deionised water supplied test results. The presented conceptual model with vapour mass transfer was based on the thermodynamic equilibrium of vapour density with temperature change and the phase transition to ice during thermal energy withdrawal. Compared to the widely used coupled heat-mass models, the vapour flow based model clearly explained the driving forces and presented a much easier algorithm for calculation. The de-icing chemical displacement was explained as the migration of the dissolved ions together with hygroscopic water transport, which in turn, was driven by cryosuction forces. The reduction of hydraulic conductivity during the secondary salinisation with sodium chloride was caused by chemical osmosis, which tended to equalise the solute concentration in pore water over the sample length. The research outcomes indicate a significant contribution to the future perspectives on frost heave modelling and prognosis. Further research could extend this work by inclusion of the vapour mass transfer in quantitative analysis for soil freezing. The effect of secondary salinisation should be also foreseen in the long term prognosis for highway subsoils exploitation.

Yes / Experimental and theoretical investigations on the flexural performance of steel reinforced ECC-concrete composite beams subjected to freeze–thaw cycles are presented in this paper. Four groups of reinforced composite beams with different ECC height replacement ratios subject to 0, 50, 100 and 150 cycles of freeze–thaw were physically tested to failure. Experimental results show that the bending capacity decreases with the increase of freeze–thaw cycles regardless of ECC height replacement ratios. However, the ultimate moment, stiffness and durability of ECC specimens and ECC-concrete composite specimens are greater than those of traditional concrete specimens, owing to the excellent tensile performance of ECC materials. With the increase of ECC height, the crack width and average crack spacing gradually decrease. According to materials’ constitutive models, compatibility and equilibrium conditions, three failure modes with two boundary failure conditions are proposed. Simplified formulas for the moment capacity are also developed. The results predicted by the simplified formulas show good agreement with the experimental moment capacity and failure modes. A parametric analysis is conducted to study the influence of strength and height of ECC, amount of reinforcement, concrete strength and cycles of freeze–thaw on moment capacity and curvature ductility of ECC-concrete composite beams.

The expansion of urban and suburban areas is a world-wide phenomena. One product of this development is a dramatic increase in impermeable surfaces and a consequent increase in stormwater runoff. Bioretention cells are one best management practice frequently used to mitigate the environmental impacts of urban stormwater runoff. To ensure that a bioretention cell will continue to perform adequately in the long term, it is imperative that the environmental conditions it will experience and their effect on its performance through time are considered during its design. Although bioretention cells are frequently used for stormwater management, very few quantitative data exist on how they perform through time and in varied physical environments. In regions with seasonal freeze-thaw cycles, it is important to understand the effects of freeze-thaw cycles on the infiltration rate of bioretention cell soil mixtures so that the integrity of the design will not be compromised by seasonal change. This project uses laboratory tests to investigate the effects of freeze-thaw cycles and sediment input on the infiltration capacity of three different bioretention cell soil mixtures. These results will provide an analog for long-term changes in bioretention cell infiltration rates due to freeze-thaw cycles, providing critical data on which soil mixture would be best implemented in geographic regions susceptible to freeze-thaw activity. Furthermore these results will inform design standards for bioretention cells to ensure their long-term performance.

Soil is the most widely used material in the construction of various civil infrastructure. Various types of soils are extensively used in its natural or compacted form in the construction of dams, canals, road and railway subgrades, and waste containment structures such as soil covers and liners. These infrastructure and foundation soils are exposed to the influence of environmental factors. In the permafrost and seasonally frozen regions, soils can be in different states (e.g., saturated or unsaturated, frozen or thawed, or combinations of them) due to the variations in moisture content and temperature. The soil-water characteristic curve (SWCC), which is the relationship between soil water content and suction, is used in the interpretation and prediction of unsaturated soils behavior. Similarly, the soil-freezing characteristic curve (SFCC), which is the relationship between unfrozen water content and subzero temperature, is used in the prediction and interpretation of frozen soils behavior. In this thesis, the SWCC and SFCC of two Canadian soils (i.e. Toronto silty clay (TSC) and Toronto lean clay (TLC)) were extensively investigated for better understanding the fundamental relationship between SWCC and SFCC. The soil resilient modulus (MR) is a key material property used in the rational design of pavements. Experimental investigations were undertaken to determine the MR of five Canadian soils (i.e., TSC, TLC, Kincardine lean clay (KLC), Ottawa Leda clay (OLC), and Indian Head till (IHT)), considering the influence of moisture and temperature, with the aid of an advanced triaxial testing equipment. Two simple models were proposed for estimating the MR of frozen soils, in this thesis. In addition, an artificial neural network (ANN) model was developed for estimating the MR of the five Canadian soils considering various influencing factors. The conclusions from the various studies in this thesis are succinctly summarized below. (1) Four expressions (i.e. power relationship, exponential relationship, van Genuchten equation, and Fredlund and Xing equation) that are widely used for representing the SFCC were selected for providing comparisons between the measured and fitted SFCCs for different soils. The results suggest that the exponential relationship and van Genuchten equation are suitable for sandy soils. The power relationship reasonably fits the SFCC for soils with different particle sizes, but not for saline silts. The Fredlund and Xing equation is flexible and provides good fits for all the soils. (2) The SFCC and SWCC of TSC and TLC were experimentally determined, analyzed, and compared. Many factors influence the reliable measurement of SFCC, which include sensors’ resolution and stability, sensor calibration for each soil, and thermodynamic equilibrium condition. The hysteresis of SFCC for the two soils is mainly attributed to the supercooling of pore water. The quantitative dissimilarity in the measured SFCC and SWCC may be attributed to specimen structure variations during compaction and saturation, and during freezing / thawing processes, and cracks formation due to sensors insertion. In addition, some fundamental differences may exist between the drying / wetting and freezing / thawing processes, resulting in dissimilarity. (3) Two novel models were proposed for the estimation of MR of frozen soils. The semi-empirical model extends the mechanics of unsaturated soils and employs SFCC for prediction. Several coarse- and fine-grained saturated soils were used to validate this model. The empirical hyperbolic model was proposed considering that the frozen MR versus subzero temperature relationship resembles hyperbola. This model was validated on coarse- and fine-grained soils under saturated / unsaturated conditions. The hyperbolic model has wider application since it can be used for both saturated and unsaturated frozen soils. Both the models are simple and promising. (4) The MR of five Canadian soils subjected to wetting and freezing was determined by using the GDS ELDyn triaxial testing system. A freezing system was established for controlling the desired testing temperatures within the soil specimens. The results suggest: (i) The effect of subzero temperature on the MR is significant. (ii) For TLC, KLC, OLC, and IHT, the frozen MR versus subzero temperature relationship of the saturated specimen typically has steeper slope than specimen at the optimum water content, for the temperature range from 0 to -5 °C. (iii) The effect of stress levels on the frozen MR depends on soil type, water content, and subzero temperature. Lastly, (iv) Loading frequency does not show a significant influence on the frozen MR. (5) The MR of the five Canadian soils was determined considering wetting and freeze-thaw (F-T) conditions. The results suggest: (i) The F-T cycles result in weak soil structure due to reduction in suction, particles movement, loss of cohesion, and formation of cracks / channels. (ii) The critical numbers of F-T cycles were determined as 1, 1, 2, and 1 for TLC, KLC, OLC, and IHT at the optimum water content, respectively. (iii) The percentage of reduction in MR after the critical number of F-T cycles was strongly related to the plasticity index for specimens tested at the optimum water content. (iv) The wetting process results in the decrease in suction and enlargement of soil pores. Consequently, relatively low MR values were measured at high water contents, and the effect of F-T cycles becomes insignificant. Finally, (v) The effect of stress levels on the MR was dependent on the initial water content of the specimen and soil type.

No description available.

Roads are subjected to mechanical loads from the traffic as well as deteriorating mechanisms originating from the surrounding environment and climate. The damage arising is particularly severe during the winter season, when for example raveling, pot holes and cracks can emerge on the surfaces of asphaltic roads. These winter related damages are difficult to characterize and predict, partly due to the complexity of the asphalt material and partly since they cannot be linked to one single phenomenon but several, such as the (long term) existence of moisture, frost damage and frost heave, low temperature cracking and the embrittlement of the mastic at low temperatures. Further adding to the complexity is the combination of these phenomena which may accelerate the emergence and evolution of the damage mechanisms. This licentiate research project is mainly focusing on the emergence and development of frost damage in the asphalt layer but will include the effect of other damage mechanisms in its continuation. The goal of the project is to develop a multiscale model able to predict the damage development in an asphalt pavement during a desired period of time, to enhance maintenance predictions as well as pavement design choices. This licentiate thesis is the first part of this project and aims to lay the foundation of the multiscale model. To achieve this, a micromechanical model of frost damage in asphalt mixtures has been developed. This model couples the moisture and mechanical damage happening on the short and long term, caused by the infiltration of moisture and the expansion of water turning into ice during temperature drops. Both possible adhesive damage in the mastic-aggregate interface and cohesive damage in the mastic is included. In addition to the developed micromechanical model, this thesis presents the overall concept for the formulation of the multiscale model as well as discusses about its motivations and advantages. / Vägar utsätts både för mekaniska laster från trafiken som kör på vägen samt för nedbrytande mekanismer härstammande från den omgivande miljön och klimatet. Skadorna som uppstår är särskilt stora under vintern, då till exempel stensläpp, potthål och sprickor kan uppstå på ytan av asfalterade vägar. Dessa vinterrelaterade skador är svåra att karakterisera och förutsäga, delvis på grund av det komplexa beteendet hos asfalt och delvis eftersom de inte härstammar från enbart ett fenomen utan flera, såsom existensen av fukt i asfalten (på lång sikt), frostskador, tjällyft, sprickbildning på grund av låg temperatur samt försprödningen av asfalt som sker vid låga temperaturer. Vidare påverkar dessa skademekanismer varandra vilket kan accelerera skadebildningen och utvecklingen, vilket ytterligare ökar komplexiteten. Detta licentiatforskningsprojekt fokuserar till största delen på uppkomsten och utvecklingen av frostskador men kommer även inkludera effekten av andra skademekanismer i dess fortsättning. Målet med detta forskningsprojekt är att utveckla en multiskalemodell som kan förutspå skadeutvecklingen i en asfaltsväg under en önskad tidsperiod, för att förbättra både underhållsprognoser samt designval. Denna licentiatuppsats är den första delen i detta projekt och syftar till att lägga grunden till multiskalemodellen. För att uppnå detta har en mikromekanisk modell av frostskador i asfalt utvecklats. Denna modell kopplar ihop fuktskadan och den mekaniska skadan som sker både på kort och lång sikt, orsakad av infiltrationen av fukt och expansionen av vatten som omvandlas till is vid sjunkande temperatur. Modellen inkluderar de möjliga skadorna som uppstår i både mastics och gränsskiktet mellan mastics och stenmaterialet. Utöver den utvecklade mikromekaniska modellen presenterar denna uppsats det övergripande konceptet för formuleringen av multiskalemodellen samt diskuterar dess motivering och fördelar. / <p>QC20190515</p>

La modélisation numérique du comportement des matériaux cimentaires sous l’action des sollicitations complexes constitue un point de vue alternatif pour identifier et évaluer les mécanismes internes qui ne peuvent être étudiés directement à travers les essais expérimentaux. A cet effet, le développement des outils de modélisation permettant la prise en compte des interactions entre la microstructure hétérogène de la pâte de ciment et le comportement macroscopique des matériaux cimentaires est fortement apprécié. Une telle approche numérique donne une meilleure description des processus physiques et évite la calibration répétitive des paramètres lorsque la microstructure change.Ce travail de thèse a pour objet de mettre au point une approche de modélisation de l’endommagement des matériaux cimentaires compte tenu des mécanismes physiques qui se produisent à l’échelle microscopique. Dans l’approche proposée, les principes de la construction d’une microstructure virtuelle de la pâte de ciment sont présentés et les paramètres micromécaniques des phases cimentaires sont identifiés. La capacité prédictive de l’approche est testée en comparant les résultats numériques aux résultats des essais expérimentaux réalisés dans ce travail et aux résultats tirés de la littérature. L’application de cette approche est ensuite illustrée à travers des simulations de la pâte de ciment sous fluage et cycles de gel-dégel. Cette approche ouvre la voie à une multitude d’applications, comme l’étude de l’effet du retrait, du fluage, des cycles de gel-dégel, de la fissuration thermique, de l’auto-cicatrisation et de la carbonatation sur les propriétés thermomécaniques des matériaux cimentaires. / Numerical modelling of the constitutivebehaviour of cementitious materials exposed to aggressive environment offers an alternative point of view for the identification and assessment of internal mechanisms which cannot be explicitly explored using standard experimental techniques. In this regard, the development of advanced modelling tools that take into account the interactions between the heterogeneous microstructure of cement paste and the macroscopic behaviour cementitious materials is highly valued. Such modelling approaches give a much better description of the physical processes and avoid recurrent parameter calibration when dealing with a different microstructure.The work presented in this PhD thesis proposes a numerical modelling approach of damage in cement based materials taking heed of the physical mechanics that can only be characterized at the microscopic level. In the proposed approach, the principles of constructing a virtual microstructure of cement paste are laid out and the micromechanical parameters of cement phases are identified. The predictive capacity of the micromechanical approach is put to the test by a comparison of numerical results with experimental data determined in the present study and found in the literature. Finally, the power of the approach is illustrated through simulations of creep and freeze-thaw behaviour at the microscopic scale of cement paste.This approach paves the way for a multitude of applications, such as the study of the effect of shrinkage, creep, freeze-thaw cycles, thermal cracking, self-healing and carbonation on the thermomechanical properties of cement-based materials.

This project concerns the effect of freeze-thaw cycles on the pore-scale structure of nonaqueous phase liquid (NAPL) contaminants in water-saturated porous media. This problem is of critical importance to the entrapment of such contaminants in cold temperate, polar and high altitude regions, and has not been examined in the literature to date. This research work is conducted in three stages: (i) two-dimensional nondestructive visualisation of residual light non-aqueous phase liquid (LNAPL), and dense non-aqueous phase liquid (DNAPL), in porous media subject to successive freeze-thaw cycles; (ii) three-dimensional experiments on LNAPL in porous media subject to freeze-thaw, with quantification of phase volumes by X-ray micro-computed tomography (micro-CT); and (iii) the explanation of results by several pore scale mathematical and conceptual models. The two-dimensional cell experiments (using a monolayer of 0.5 mm diameter glass beads held between two glass sheets), and three-dimensional X-ray micro-CT experiments reveal a substantial mobilisation and rupture of ganglia during successive freeze-thaw cycles; this includes the detachment of smaller ganglia from larger ganglia and the mobilisation of NAPL in the direction of freezing front. The experiments also reveal significant shedding of numerous single/sub-singlet ganglia along narrow pore corridors, their entrapment in growing polycrystalline ice, and the coalescence of such small ganglia during thawing to form larger singlets. These changes were more predominant where the freezing commenced. The results of the experimental studies were interpreted by developing several mathematical and conceptual models, including freezing-induced pressure model, Darcy's law model, multipore ganglia model (rupture coefficient) and ice-snap off model.

During the industrialization of the 19th century the negative health effects of vitamin D was discovered as children in the cities developed osteomalacia or more commonly known as rickets caused by vitamin D deficiency. Vitamin D is produced in the skin from 7-dehydrocholesterol during sun-exposure and enhances intestinal phosphor and calcium absorption thus enhancing the bone remodeling process. Now, in the 21st century, Vitamin D is still relevant as positive health effects have been recognized and with it an increased number of samples and a demand for accurate analyzing. Vitamin D is commonly believed to be sensitive to ultraviolet radiation in serum and blood samples and therefore have traditionally been kept protected from light exposure from the time of sampling until the finished analyze. However recent studies have proven 25- hydroxyvitamin D (25[OH]D) to be stable in both whole blood and serum. As previous studies have been primarily conducted in research laboratories with the aim to study vitamin D under specific research-laboratory conditions the aim of this study was to study the stability of 25[OH]D in serum and whole blood within both primary care- and hospital laboratories under normal and exaggerated conditions with the purpose to evaluate possible pre-analytical issues with everyday handling processes. The assay used was high pressure liquid chromatography-tandem mass spectrometry, HPLCMS/MS, and the sought analytes 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3, 25[OH]D2 and 25[OH]D3. The results showed that 25-hydroxyvitamin D is stable in serum for 24 hours at room temperature whilst exposed to light both ultraviolet and fluorescent. The analyte is also stable for up to four freeze-thaw cycles rendering the process of light-protection and samples frozen immediately after centrifugation superfluous. The results also ensure reliable results even if samples are accidently left on benchtops or saved refrozen to be reanalyzed at a later date. / Under den industriella revolutionen på 1800 talet upptäcktes de negativa hälsoeffekterna av vitamin D-brist då barnen i städerna utvecklade rakit (osteomalaci) eller engelska sjukan som sjukdomen också kallas på grund av brist på sol och D-vitamin. Vitamin D produceras i huden från 7-dehydrokolesterol vid solexponering och ökar upptaget av fosfor och kalcium i tarmen som i sin tur förbättrar återuppbyggnaden av skelettet. Vitamin D är fortfarande aktuell även nu i vår tid men då för dess nyupptäckta hälsofrämjande egenskaper som till exempel förebyggandet av coloncancer. Detta medför även en ökning av antalet analyser och kräver därmed en adekvat analysmetod. Traditionellt har det antagits att vitamin D är ljuskänsligt i alla former därför har blod och serum ljusskyddats, från provtagningstillfället fram tills dess att analysen är utförd. Dock har nya studier visat att 25-hydroxyvitamin D (25[OH]D) är mycket stabilt bundet till vitamindbindande protein i både serum och helblod. Syftet med studien var att utvärdera om 25[OH]D i serum och helblod behöver ljusskddas genom att studera stabiliteten hos 25[OH]D i både serum och helblod under normala primärvårdslaboratorie- och sjukhuslaboratorieförhållanden samt under extrema förhållanden för att utvärdera eventuella preanalytiska problem eller fel relaterade till den vardagliga hanteringen av vitamin D prover. Proverna analyserades med högupplösande vätskekromatografi-tandem masspektrometri, HPLC-MS/MS, och de sökta analyterna var 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3, 25[OH]D2 och 25[OH]D3. Resultat från studien visade att 25-hydroxyvitamin D är stabilt i serum i 24 timmar i rumstemperatur med ljusexponering från både ultraviolett och fluorescerande ljus. 25-hydroxyvitamin D är även stabil i serum upp till fyra frys- och tiningscykler. Detta gör att provhanteringen kan förenklas genom att dessa prover inte behöver ljusskyddas samt att serumet ej behöver frysas in direkt efter centrifugering. Resultatet säkerställer även tillförlitliga resultat om prover lämnas framme på bänken av misstag eller om prover behöver sparas och frysas om för att analyseras vid senare tillfälle.

Because winter maintenance is so costly, Utah Department of Transportation (UDOT) personnel asked researchers at Brigham Young University to determine whether asphalt or concrete pavements require more winter maintenance. Differing thermal properties suggest that, for the same environmental conditions, asphalt and concrete pavements will have different temperature profiles. Climatological data from 22 environmental sensor stations (ESSs) near asphalt roads and nine ESSs near concrete roads were used to 1) determine which pavement type has higher surface temperatures in winter and 2) compare the subsurface temperatures under asphalt and concrete pavements to determine the pavement type below which more freeze-thaw cycles of the underlying soil occur. Twelve continuous months of climatological data, primarily from the 2009 calendar year, were acquired from the road weather information system operated by UDOT, and erroneous data were removed from the data set. To predict pavement surface temperature, a multiple linear regression was performed with input parameters of pavement type, time period, and air temperature. Similarly, a multiple linear regression was performed to predict the number of subsurface freeze-thaw cycles, based on month, latitude, elevation, and pavement type. A finite-difference model was created to model surface temperatures of asphalt and concrete pavements based on air temperature and incoming radiation. The statistical analysis predicting pavement surface temperatures showed that, for near-freezing conditions, asphalt is better in the afternoon, and concrete is better for other times of the day, but that neither pavement type is better, on average. Asphalt and concrete are equally likely to collect snow or ice on their surfaces, and both pavements are expected to require equal amounts of winter maintenance, on average. Finite-difference analysis results confirmed that, for times of low incident radiation (night), concrete reaches higher temperatures than asphalt, and for times of high incident radiation (day), asphalt reaches higher temperatures than concrete. The regression equation predicting the number of subsurface freeze-thaw cycles provided estimates that did not correlate well with measured values. Consequently, an entirely different analysis must be conducted with different input variables. Data that were not available for this research but are likely necessary in estimating the number of freeze-thaw cycles under the pavement include pavement layer thicknesses, layer types, and layer moisture contents.