Swelling clay is an important and challenging geological feature in tunnelling projects.The behaviour of swelling clay is influenced by many internal and external factors.This, combined with a lack of experience and knowledge has resulted in challengeswhen accounting for the swelling phenomena. In addition to this, there is a lack ofunderstanding for the calculation of rock support when swelling clay is present. Themain objectives of this thesis were to compare laboratory methods used to measure theswelling potential, identify possible uncertainties when performing oedometer tests,and to provide a model for design of rock support for single zones with swelling clay.To support these objectives, a literature review has been conducted and laboratory testshave been performed to determine swelling properties using clay samples collectedfrom a tunnel failure in Sweden. In addition, a model has been derived for design ofrock support when swelling clay is present in single zones of different widths. Theresults from the laboratory tests showed that the clay sample could be characterizedas active respectively moderately active clay. The results of the model for design of rocksupport showed that the width of the swelling zone and the swelling pressure have asignificant impact on the shotcrete thickness, rebar spacing and reaction forces at therock bolts. However, future research for design of rock support is required as well asdevelopment of a more detailed standard for testing of swelling clay.

No description available.

A polymer laminate consisting of multiple layers of proprietary blends of Ethylene Vinyl Alcohol (EVOH) and Thermoplastic Polyurethane (TPU) and used in the construction of air bladders was evaluated for hygroscopic effects driving delamination and multiple layer fragmentation. These air bladders are observed to suffer delamination during a manufacturing process that involves immersion in an alcohol/water solution. A plausible underlying mechanism is differential swelling and absorption by the laminate constituents. Both room and elevated temperature swelling tests were carried out to find the absorption and swelling coefficients of the constituents. These coefficients served as input into a Finite Element Analysis (FEA) model used to predict laminate failure. The diffusion coefficient for EVOH could not be obtained because the material did not reach saturation within the available timeframe of the experiment. The diffusion coefficient of the TPU was found to be 4.09E-12 [m^2/s] at room temperature and 1.26E-11 [m^2/s] at 40°C. The diffusion coefficient for TPU was an order of magnitude larger at elevated temperature and the TPU reached saturation much quicker than the EVOH, suggesting that the diffusion coefficient for the TPU was significantly greater than that of the EVOH. The swelling coefficients were 1.03E-3 m^3/kg and 9.97E-4 m^3/kg for the EVOH at room temperature and 40°C respectively, and 1.16E-3 m^3/kg and 1.09E-3 m^3/kg for the TPU at room temperature and 40°C respectively. The swelling coefficient was very close across materials and within the margin of error across temperatures. These results are required for future FEA simulations to confirm that differential swelling is the driving mechanism behind debonding and laminate failure. Tensile testing was done on laminated sheets used in production to identify cracking and layer separation at strains of 20%, 40%, and 100%. Scanning Electron Microscope (SEM) imaging was used to understand damage initiation and accumulation in the layers.

Yes / Articular cartilage is a vascular tissue with limited repair capabilities, leaving an afflicted person in extreme pain. The tissue experiences numerous forces throughout its lifetime. This study focuses on development of a novel hydrogel composed of chitosan and β-glycerophosphate for articular cartilage repair. The aim of this study was to investigate the mechanical properties and swelling behaviour of a novel hydrogel composed of chitosan and β-glycerophosphate for cartilage repair. The mechanical properties were measured for compression forces. Mach-1 mechanical testing system was used to obtain storage and loss modulus for each hydrogel sample to achieve viscoelastic properties of fabricated hydrogels. Two swelling tests were carried out to compare water retaining capabilities of the samples. The hydrogel samples were made of five different concentrations of β-glycerophosphate cross-linked with chitosan. Each sample with different β-glycerophosphate concentration underwent sinusoidal compression forces at three different frequencies -0.1Hz, 0.316Hz and 1Hz. The result of mechanical testing was obtained as storage and loss modulus. Storage modulus represents the elastic component and loss modulus represents the viscosity of the samples. The results obtained for 1Hz were of interest because the knee experiences frequency of 1Hz during walking.

Diblock copolymers have many interesting properties, which first and foremost include their ability to self-assemble into various ordered, regularly spaced domains with nanometer-scale feature sizes. The work in this dissertation can be logically divided into two parts - the first and the majority of this work describes the phase behavior of certain block copolymer systems, and the second discusses real applications possible with block copolymer templates. Many compressible fluids have solvent-like properties dependent on fluid pressure and can be used as processing aids similar to liquid solvents. Here, compressed CO2 was shown to swell several thin homopolymer films, including polystyrene and polyisoprene, as measured by high pressure ellipsometry at elevated temperatures and pressures. The ellipsometric technique was modified to produce accurate data at these conditions through a custom pressure vessel design. The order-disorder transition (ODT) temperatures of several poly(styrene-b-isoprene) diblock copolymers were also investigated by static birefringence when dilated with compressed CO2. Sorption of CO2 in each copolymer resulted in significant depressions of the ODT temperature as a function of fluid pressure, and the data above was used to estimate the quantitative amount of solvent in each of the diblock copolymers. These depressions were not shown to follow dilution approximation, and showed interesting, exaggerated scaling of the ODT at near-bulk polymer concentrations. The phase behavior of block copolymer surfactants was studied when blended with polymer or small molecule additives capable of selective hydrogen bonds. This work used small angle X-ray scattering (SAXS) to identify several low molecular weight systems with strong phase separation and ordered domains as small as 2-3 nanometers upon blending. One blend of a commercially-available surfactant with a small molecule additive was further developed and showed promise as a thin-film pattern transfer template. In this scenario, block copolymer thin films on domain thick with self-assembled feature sizes of only 6-7 nm were used as plasma etch resists. Here the block copolymer's pattern was successfully transferred into the underlying SiO2 substrate using CF4-based reactive ion etching. The result was a parallel, cylindrical nanostructure etched into SiO2.

I världens omvandling mot en bioekonomi kommer lignocellulosa material spela en stor roll i ersättningen av fossila resurser. Lignin är den mest tillgängliga källan av förnybara och naturligt förekommande aromatiska ämne och den utgör 15–30% av ved. Det lignin som är för nuvarande tillgängligt i marknaden är begränsat i sina appliceringar på grund av ämnets komplexa och outforskade kemisk struktur. I ett försök att bidra till ’lignin-först’ bioraffinaderi konceptet, undersöker detta arbete effekten av urea och karboxymetylering som förbehandlingsmetoder på utbyte av lignin såväl som de kemiska och fysiska egenskaperna av lignin. Karaktäriseringstekniker som Fourier-transform infra-red och nuclear magnetic resonance spectroscopy används för att analysera den kemiska strukturen av ligninet efter extraktion. Det resulterade i att båda förbehandlingsmetoder ökade utbytet av lignin med mellan 1% och 16%. Urea förbehandlingen hade ingen effekt på den kemiska strukturen av varken fibrer eller lignin. Men, karboxymetylering förbehandlingen ändrade i kemiska strukturen av lignin genom att lägga till karboxymetyl-grupper i både den alifatiska och den fenoliska regionen. Medans att öka förbehandlingstiden ökade utbyte i båda förbehandlingsmetoder, hade detta effekten att minska mängden kvantifierbara bindningar mellan enheterna för karboxymetylering förbehandlingen. Dessa diskuterade metoder har potential att användas i valorisering av lignin. / In the world’s transformation towards a bioeconomy, lignocellulosic biomass plays a key role as a substitute for fossil-based resources. Lignin is the most abundant source of renewable and naturally occurring aromatics and it constitutes 15-30% of lignocellulosic biomass. The technical lignin currently available on the market is limited in its applications because of its complex and poorly understood chemical structure. To contribute to the lignin-first biorefinery concept, this work investigates the effect of urea and carboxymethylation pretreatments on the yield as well as the chemical and physical properties of lignin. Characterization techniques such as Fourier-transform infra-red and nuclear magnetic resonance spectroscopy were utilized to analyze the molecular structure of the lignin product after extraction. It was shown that both pretreatment methods resulted in higher yields between 1% and 16%. The urea pretreatment had no effect on the chemical structure of the fibers nor the lignin. However, carboxymethylation altered the chemical structure of the lignin by adding carboxymethyl groups in both the aliphatic and phenolic regions. While increasing the pretreatment time increased the yield for both pretreatment methods, in the case of carboxymethylation it reduced the amount of quantifiable inter-unit linkages. Overall, the pretreatment methods discussed have potential use for lignin valorization.

The extracellular matrix (ECM) of the aorta is a complex meshwork of elastin, collagen, and glycosaminoglycans (GAG). It also modulates the mechanical properties of the aorta, which in turn dictate lethal ruptures such as those caused by aneurysm and dissection. Amongst other roles, aortic stiffness controls the aorta’s ability to expand and recoil, and residual stresses, which are those existing in the absence of load, affect the magnitude and distribution of the mechanical stresses throughout the aortic wall. Mechanical stresses can be predicted via complex computer models, powerful tools that can also provide insight regarding the risk of rupture, given that ruptures occur when the mechanical stresses exceed the strength of the aorta. While this dissertation is primarily focused on the effect of GAG on residual stresses, other ECM (collagen, elastin) and mechanical (stiffness) factors are considered to expand our understanding of the structure-mechanics relationship in the aorta. This is important because the ECM undergoes extensive remodelling during aging and disease, but it is also critically important, as mentioned, in the context of aortic rupture. We first explored the mechanical roles of GAG in a finite element model by studying both the transmural residual stresses and the opening angle (an indicator of circumferential residual stresses) in ascending (AS) aortic ring models. Both were shown to be modulated by the GAG content, gradient, and the nature of the transmural distribution. While a heterogeneous GAG distribution led to the development of residual stresses which could be released by a radial cut, this was not the case when a homogeneous distribution was prescribed. Because the GAG distributions used in the first study were based on assumptions, and to get an in vitro understanding of the ECM role in modulating residual stresses, biomechanical mechanisms were explored in thoracic aortas from 5- to 6-month-old pigs. In a second study, we generated new detailed data on the distributions of collagen, elastin and GAG, throughout the aortic wall in the AS, arch (AR), and descending thoracic (DT) regions, and established correlations between the ECM constituents and the opening angle. The strongest correlations were observed between the opening angle and the total collagen:GAG ratio as well as the total GAG content. In line with our first in silico work, this in vitro investigation revealed that the GAG content and gradient modulate circumferential residual stresses and suggested that the interaction between GAG and the ECM fibers also plays a role in regulating residual stresses. In a third study, we examined the extent of contribution of GAG to circumferential residual stresses and to the radial compressive stiffness of the aortic wall, as well as the underlying mechanism through which GAG contribute to the mechanical properties using enzymatic GAG depletion. GAG depletion was associated with a decrease in the opening angle, by approximately 25%, 32%, 42% in the AS, AR, and lower DT regions respectively, and an increase in the radial compressive stiffness of the AS aorta. Glycation was also associated with a decrease in the opening angle, in which GAG depletion also had a similar effect. A small loss of water content was detected after GAG depletion, and the AS region was also associated with a significant loss of compressive deformation in the inner layer of the aorta following GAG depletion, suggesting that GAG interact with ECM fibers in their effect on aortic mechanics. The garnered experimental geometrical data and intramural GAG distributions were finally used to simulate animal-specific aortic rings from the AS, AR, and DT regions. The opening angle response was evaluated in solid matrices assuming one layer, and two layers to capture the different mechanical behaviors of the intima-media and the adventitia. A Holmes-Mow constitutive relationship was used and material parameters were obtained by curve fitting experimental stress-strain curves obtained from biaxial tests. Numerical results were evaluated by comparing simulated and experimental opening angles, revealing a notable overall agreement between the two.

The Yazoo Clay is a calcareous fossiliferous mudrock that outcrops in a northwest-southeast belt across much of Mississippi and in adjacent states. Based on over 240 X-ray diffraction analyses, the average composition of the Yazoo Clay is 28% smectite, 24% kaolinite, 22% quartz, 15% calcite, 8% illite, 2% feldspar, and 1% gypsum. Exposed Yazoo clay is weathered to a depth of 30-40 ft. and has a distinctive yellow/brown color; unweathered Yazoo is blue/gray. In most wells, smectite is more abundant in weathered clay than in unweathered clay. Mineralogic changes correlate well with engineering properties of the samples, which in general show a decrease in plasticity indices with depth. Weathered Yazoo clay exhibits greater mineralogic variability than unweathered clay. Mineralogical content also varies laterally. Lateral variation, along with correlative smectite content and engineering properties, is the reason for ?roller coaster? roadways and structural damage caused by the swelling Yazoo Clay.

Natural soils in work-sites are sometimes detrimental to the construction of engineering projects. Problematic soils such as soft and expansive soils are a real source of concern to the long-term stability of structures if care is not taken. Expansive soils could generate immense distress due to their volume change in response to a slight change in their water content. On the other hand, soft soils are characterised by their low shear strength and poor workability. In earthwork, replacing these soils is sometimes economically and sustainably unjustifiable in particular if they can be stabilised to improve their behaviour. Several techniques have evolved to enable construction on problematic soils such as reinforcement using fibre and planar layers and piled reinforced embankments. Chemical treatment using, e.g. lime and/or cement is an alternative method to seize the volume change of swelling clays. The use of lime as a binding agent is becoming a popular method due to its abundant availability and cost-effectiveness. When mixed with swelling clays, lime enhances the mechanical properties, workability and reduces sensitivity to absorption and release of water. There is a consensus in the literature about the primary mechanisms, namely cation exchange, flocculation and pozzolanic reaction, which cause the changes in the soil characteristics after adding lime in the presence of water. The dispute is about whether these mechanisms occur in a sequential or synchronous manner. More precisely, the controversy concerns the formation of cementitious compounds in the pozzolanic reaction, whether it starts directly or after the cation exchange and flocculation are completed. The current study aims to monitor the signs of the formation of such compounds using a geotechnical approach. In this context, the effect of delayed compaction, lime content, mineralogy composition, curing time and environmental temperature on the properties of lime-treated clays were investigated. The compaction, swelling and permeability, and unconfind compression strength tests were chosen to evaluate such effect. In general, the results of the geotechnical approach have been characterised by their scattering. The sources of this dispersion are numerous and include sampling methods, pulverisation degree, mixing times and delay of compaction process, a pre-test temperature and humidity, differences in dry unit weight values, and testing methods. Therefore, in the current study, several precautions have been set to reduce the scattering in the results of such tests so that they can be used efficiently to monitor the evolution in the properties that are directly related to the formation and development of cementitious compounds. Four clays with different mineralogy compositions, covering a wide range of liquid limits, were chosen. The mechanical and hydraulic behaviour of such clays that had been treated by various concentrations of lime up to 25% at two ambient temperatures of 20 and 40oC were monitored for various curing times. The results indicated that the timing of the onset of changes in mechanical and hydraulic properties that are related to the formation of cementitious compounds depends on the mineralogy composition of treated clay and ambient temperature. Moreover, at a given temperature, the continuity of such changes in the characteristics of a given lime-treated clay depends on the lime availability.

No description available.